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Aggression and Violent Behavior

xx (2004) xxx–xxx

ROOFIntentional injury and the behavioral syndrome

Anthony R. Mawson*

Institute of Epidemiology and Health Services Research, School of Public Health, College of Public Service,

Jackson State University, 350 West Woodrow Wilson Avenue, Suite 2301-B, Jackson, MS 39213-7581, USA

Received 2 January 2002; received in revised form 17 June 2002; accepted 24 May 2004

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NCORRECTED PAbstract

Injuries are currently classified as intentional or unintentional. Worldwide, intentional injury

accounts for about 4400 deaths per day, and 1.6 million people were estimated to have died from

violence in 2000. However, in epidemiologic studies of intentional injury, the injurer is typically

unavailable or ignored in the data collection process, and actual intentions are rarely known or

investigated. In practice, injurious intent is inferred when an injury is inflicted. While all allegedly

intentional injuries are inflicted by the self or others, a review of the literature indicates that few

inflicted injuries are intentional. The thesis of this paper is that the concept of intentional injury

perpetuates an oversimplified view of both injurer and injured. Many injury victims are former

perpetrators and vice versa; many have experienced multiple injuries, including self-inflicted injury;

and many have histories of substance abuse, alcoholism, criminality, and other characteristics that form

what can be described as a behavioral syndrome, of which susceptibility to injury (as perpetrator and/

or victim) is one manifestation. The behavioral syndrome is hypothesized to represent a generalized,

tropism-like tendency to seek varying intensities of sensory stimulation.

D 2004 Published by Elsevier Ltd.

Keywords: Injury; Violence; Aggression; Intentional; Epidemiology; Sensory; Stimulation; Behavior; Health;

Review

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U1. Introduction

An important milestone was reached in the historical development of the field of injury

control when the customary term accident was replaced by that of injury. The former term

1359-1789/$ – see front matter D 2004 Published by Elsevier Ltd.

doi:10.1016/j.avb.2004.05.003

* Tel.: +1-601-979-1102.

E-mail address: armawson@aol.com (A.R. Mawson).

AVB-00316; No of Pages 31

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A.R. Mawson / Aggression and Violent Behavior xx (2004) xxx–xxx2

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had the misleading connotation of being a random event and therefore one about which little

could be done in terms of prevention. On the contrary, injuries were found to be far from

random. Like other health outcomes, their occurrence was patterned and predictable in terms

of identifiable risk factors. This implied that injuries could be prevented and the fatalistic

attitude implicit in the concept of accident could be abandoned; furthermore, injuries came to

be seen as the direct result of exchanges of mechanical and other forms of energy that exceed

the body’s tolerance threshold (Gibson, 1961; Haddon, 1963, 1970). This was a major

advance, the thrust of which was that injuries could be prevented by modifying the

environment so as to prevent the excessive exchanges of energy that actually cause them,

rather than by attempting (for the most part unsuccessfully) to change people’s attitudes and

behavior. By changing the environment, everyone is protected automatically—the compliant

and noncompliant—and especially those at high risk. For instance, motor vehicle crash-

related deaths and injuries are effectively prevented or reduced in severity by padded vehicle

interiors and airbags (Hemenway, 2002). As with past successes in solving public health

problems, changing the environment continues to hold great promise as a means of reducing

the overall burden of injury. However, the need still remains to explain different types of

injury as well as differential susceptibility to injury in terms of factors peculiar to the

individual (Goldstein, 1985; Runyan, 1993; Russell, 1998).

The concept of injury has largely replaced that of accident, but the field remains dominated

by a distinction between unintentional and intentional injury, reminiscent of the older

dichotomy of ‘‘accidental’’ and ‘‘intentional’’ injury. To paraphrase Kraus, Peek-Asa, and

Vimalachandra (1998), unintentional injuries have no human intentional motivation and

include injuries from traffic-related events, falls, drowning, and most poisonings, whereas

intentional injuries have ‘‘discernible human motivation’’ and may be self-directed, such as

suicide, or outwardly directed, such as homicide and assault. Intentional injury, also referred

to as violence, has been defined as ‘‘the use of force with the intent to inflict injury upon

oneself or another’’ (National Committee for Injury Prevention and Control, 1989).

The contribution of intentional injury to the overall burden of trauma and illness increases

markedly during adolescence. In Sweden, for instance, the incidence of self-inflicted injury

among girls ages 15–19 is close to that of traffic injury (Engstrom, Diderichsen, &

Laflamme, 2004). Worldwide, intentional injury accounts for about 4400 deaths per day.

In 2000, 1.6 million people are estimated to have died from violence (a rate of 28.8 per

100,000 population). Nearly half of these deaths were suicides, nearly a third were homicides,

and a fifth were war related. Also worldwide, from 10% to 69% of women report having been

physically assaulted by an intimate partner during their lifetime (Krug, Mercy, Dahlberg, &

Zwi, 2002).

It is obvious that behavior contributes directly to the occurrence of injury; the existence of

abuse, maltreatment, and torture among human beings is all too apparent. However, a major

thesis of this paper is that the concept of intentional injury perpetuates an oversimplified view

of both injurer and injured. Injuries are classified on the basis of what is presumed to be the

intent of the injurer. Yet, a remarkable fact about contemporary epidemiologic research on

intentional injury, given the prominence of this distinction, is that the injurer is usually

unavailable or ignored in the data collection process and injurious intent is taken for granted,

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A.R. Mawson / Aggression and Violent Behavior xx (2004) xxx–xxx 3

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with little or no attempt at verification. Injurious intent is usually based in practice on whether

the injury was inflicted, not on an assessment of the perpetrator’s actual intentions or state of

mind. Intentions are rarely known and seldom investigated.

All allegedly intentional injuries are inflicted by the self or others, but few inflicted injuries

are clearly intentional. The literature suggests that most result from unplanned, impulsive

actions, the conscious reasons for which are often obscure to the subjects themselves.

Employing the term intentional injury in research studies usually begs the question of intent

and incorrectly labels most interpersonal and self-inflicted injuries; its existence also obscures

important underlying features common to all types of serious and fatal injury. This paper

questions the validity and overall usefulness of the concept of intentional injury and outlines

an alternative model that has novel implications for prevention and treatment. It is proposed

that susceptibility to injury (as victim or perpetrator) is one manifestation of a behavioral

syndrome that can be characterized as a generalized, tropism-like tendency to seek intense

sensory stimulation.

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NCORRECTED 2. Labeling injuries as intentional or unintentional

In a major epidemiologic study that typifies current labeling practices, 4 years of data were

reported from a population-based trauma registry in Nevada, representing over 19,000

injuries classified as unintentional, self-inflicted, or the result of assault (Niemcryk, Hines,

Brawley, & Yount, 1998). Most of the injuries were classified as unintentional, but intentional

injuries accounted for almost half of the injury-induced deaths. Persons with ‘‘intentional

injury’’ were almost five times as likely to die from their injuries as those with unintentional

injury (49% versus 10%); self-inflicted injury accounted for 6% of all injuries but 28% of all

deaths; and firearms were involved in 88% of the self-inflicted injuries, the latter tending to

occur in urban counties, among Caucasians, and in those age 65 and older.

At issue here is the meaning or interpretation of these data—the conceptual framework for

describing and understanding injuries. The implication is that intentional, self-inflicted, and

assault-related injuries represent relatively immutable categories for which independent sets

of risk factors and explanations should be sought. Is this the case? Until recently, intentional

injury was studied from different points of view under three overlapping domains within

criminology, psychiatry, and emergency medicine (see Table 1).

When violence came to be seen as a public health problem and the field of injury

epidemiology emerged, both in the mid-1980s, the subject matter was classified under two

major headings: unintentional and intentional injury (Institute of Medicine, 1985). This all-

Ut1.1Table 1

Intentional injury research within academic disciplines t1.2

Injury domain Discipline t1.3

Crimes of violence (e.g., homicide and assault) Criminology t1.4Suicide and self-injury Psychiatry t1.5Assault-related injury Emergency medicine t1.6

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A.R. Mawson / Aggression and Violent Behavior xx (2004) xxx–xxx4

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or-nothing distinction subsumes under one category all injuries in which no injurious intent is

discernible, and under the other category all injuries that allegedly result from someone’s

intention to produce that result. The latter category thus includes cases of self-inflicted injury

as well as cases in which people are intentionally injured by others.

Fatal injuries are assessed more carefully in terms of intent than nonfatal ones. In

inflicted injuries as a whole, coroners record a verdict of suicide only if there is clear

evidence of intent, whereas clinicians are more prepared to balance probabilities, which

can lead to discrepancies (O’Donnell & Farmer, 1995; Rockett & Smith, 1995). A study

of 302 hospitalized, fatally injured children in New York City compared classification of

intentional injury on hospital discharge forms with that on death certificates. Using death

certificates as the criterion, sensitivity of hospital data for identifying intentional injuries

by age and race ranged from 0.5 for children under age 5 to 0.85 for adolescents, and

from 0.75 for white children to 0.89 for nonwhite children, suggesting that hospital

discharge data underestimate both the incidence and the proportion of fatal injuries due to

‘‘intentional’’ causes, especially in the very young and in white children (Olsen & Durkin,

1996).

The question of intent is carefully evaluated when the nature of the injury calls for police

involvement, because it forms the basis of criminal prosecution and sentencing. But when

injury coding is solely a medical or research decision, intentions are less likely to be

evaluated with care. External (E) cause-of-injury codes (Centers for Disease Control and

Prevention, 2000) are not routinely completed and, when they are, coding is usually based on

inference and information in the patient’s chart. Because it is impossible to interview the

perpetrator in fatal self-injury as well as in many interpersonal injury cases, injuries are

presumed to be intentional when the evidence suggests: (1) the injury was inflicted by

someone; (2) the actions that led to injury were well aimed and apparently deliberate; and (3)

the injury was inflicted with a weapon. Occasionally, there may also be evidence of (4)

planning (premeditation).

In assuming injurious intent in cases of interpersonal injury, the perpetrator/offender tends

to be stigmatized as blameworthy and deserving of punishment, whereas the injured party is

often cast in the role of innocent victim. Another widespread assumption is that the risk

factors for intentional (or ‘‘violent’’) injury are different from those for unintentional (or

‘‘nonviolent’’) injury. The questions we examine here are the following: To what extent can

injuries be said to be truly intentional? And how useful is the concept of intentional injury in

terms of explanation and prevention?

A review of the literature suggests that ‘‘intentional injury’’ is a misinterpretation of

most injuries to which the term is applied; intentional and unintentional injuries are closely

related; and injury is part of a broader, more complex phenomenon or behavioral

syndrome. It is proposed that the underlying basis of the behavioral syndrome is a

tropism-like tendency to seek intense sensory stimulation; increased stimulation-seeking

behaviors (SSBs) directly or indirectly increase the probability and/or severity of injury to

self or others. The model suggests that the behavioral syndrome could be ameliorated—and

the associated risk of injury reduced—by providing susceptible persons with alternative

forms of sensory stimulation to substitute for that obtained in harmful ways.

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3. When are injuries intentional?

Injurious intent is usually assumed when apparently deliberate and well-directed behavior

results in injury (especially when the injury was inflicted with a weapon and there was

evidence of premeditation). This is likely to stem from the conviction that such behavior must

have been intended to produce this result. Thus, when Person X takes aim and strikes or

shoots Person Y (or himself), we take it for granted that X was trying to do something to Y:

namely, to cause injure or death. However, in all but a few instances of self-directed or

interpersonal injury, injurious intent is either unproven, impossible to prove, inapplicable, or

reportedly absent.

3.1. Difficulty establishing whether injury was inflicted

Injuries to others resulting from, say, flailing one’s arms about, knocking over a kettle of

hot water while carrying other utensils, or walking into the path of a dart thrown at a board in

a pub, would clearly not be considered intentional. Often, however, it is difficult to determine

if an injury was actually inflicted by someone, a fact that cannot always be deduced from the

patient’s demographic or social characteristics, the pattern of somatic complaints, or from

trauma to certain body parts (Muelleman, Lenaghan, & Pakieser, 1996). Even injuries

suggesting assault, such as facial contusions and trauma, are associated with interpersonal

injury in less than 50% of cases (Fanslow, Norton, & Spinola, 1998). As Abbott (1998) has

pointed out, the criteria for intentional injury remain ‘‘murky’’ even for patients with

identified assaults, and chart diagnosis is potentially subject to selection bias.

Consider the problem of determining whether a death was due to natural causes or injury.

In distinguishing between Sudden Infant Death Syndrome (SIDS) and infanticide, for

instance, federal (NICHD) guidelines require that a diagnosis of SIDS be reserved only for

infants whose death remains unexplained after a thorough investigation that includes a

complete autopsy, an examination of the death scene, and a review of the clinical history

(Meadow, 1999). The diagnosis of SIDS is thus one of exclusion, given only after considering

and rejecting every circumstance in which the death could have been due to inflicted injury.

In a study of the medical records of 19,000 U.S. children hospitalized with blunt trauma, 10%

of those under age 5 were judged to have been abused. The latter tended to have more serious

injuries; they were three times more likely to have intracranial injuries than those hurt

accidentally; and retinal hemorrhage appeared in 28% of abused cases compared with only

one in 1500 (0.66%) of the unintentional injury cases (DiScala, Sege, Li, & Reece, 2000).

It has been widely assumed that severe subdural and retinal bleeding in an infant is due to

violent, intentional shaking by a parent or caretaker (‘‘shaken baby syndrome’’). These

assumptions have been challenged on the grounds that evidence for the syndrome is

inadequate, precise and reliable case definitions are absent, and interpretations tend to

overstep the data (Donohoe, 2003; Lantz, Sinai, Stanton, & Weaver, 2004).

Other studies have suggested that low-level falls may prove fatal and result in subdural and

retinal bleeding (Plunkett, 2001). Abused infants also tend not to have severe traumatic brain

injury, and the structural damage associated with death may be morphologically mild

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(Geddes, Hackshaw, Vowles, Nickols, & Whitwell, 2001). These reports have raised

questions about the validity of other widely accepted beliefs in the field of infant injury

(Geddes & Plunkett, 2004).

Summary statistics that dichotomize injuries as ‘‘intentional’’ or ‘‘unintentional’’ are known

to be highly inaccurate. It has been claimed that only 11% of ‘‘unintentional injuries’’

involving children are truly unintentional and that up to 30% are clearly identified as instances

of maltreatment (Ewigman, Kivlahan, & Land, 1993). A review of the medical records of 287

hospitalized children under 6.5 years with head injuries suggested that 20% of the cases were

abuse related. Subdural hematomas occurred in half of the abused group, compared to only

10% in the controls. The abused were also significantly younger (mean age 0.7 years compared

with 2.5 years in the nonabuse-related group; Reece & Sege, 2000). Severe head trauma in a

very young child should clearly raise suspicion unless the circumstances of injury are well

documented. Even in the absence of retinal bleeding or subdural hematoma, it would be

inappropriate to rule out abuse without a full assessment of the circumstances.

It could be argued that what is important for descriptive, practical, and dispositional

purposes is simply whether an injury of uncertain origin was actually inflicted, not so

much whether the perpetrator truly intended to cause injury. Knowing that the injury was

inflicted would establish its origin and perhaps prevent future occurrences. However,

while inflicted and apparently deliberate injury are often equated with intentional injury,

knowing that an injury was inflicted, well directed, and apparently deliberate does not

prove that an intention to inflict injury was present at the relevant moment. Such facts do

not bear directly on the question of the perpetrator’s intentions. It is not that the criteria

for injurious intent are unclear, but that nothing can substitute for the word of the

perpetrator in establishing its existence. Injurious intent can only be determined by

questioning the person responsible for the injury, and in some cases, the person’s family

or close friends. But even if injurious intent is acknowledged and admitted, such an

admission cannot always be taken at face value. The issue of motivation is complex and

often clouded by other factors.

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UNCO4. Problems in establishing injurious intent in apparently obvious cases

Injuries are commonly classified as intentional on the basis of whether the injury was

inflicted, which itself may be difficult to prove. Because the injurer is unavailable or

ignored in epidemiologic studies, intentions are rarely known or investigated. Clearly, there

are circumstances in which injury can be described as intentional, as in some drug-related

and contract killings, but they are uncommon (Prothrow-Stith & Weissman, 1993).

Classically, it has been said that fewer than 5% of all homicides are both intentional and

premeditated (Ferracuti & Newman, 1974). In summary statistics of ‘‘intentional’’ or

‘‘unintentional’’ injuries, the state of mind of the injurer is far from obvious and intent

cannot be assessed (Ferguson, 1996). Indeed, injurious intent cannot usually be proven or

disproven, and it is often denied. Allegedly intentional injury is not always what it seems.

Injuries may have resulted from apparently well-directed and deliberate action, but that

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does not necessarily mean that the subject actually intended his or her actions to have this

result. Injuries that appear to be intentional are often found to be otherwise. Expanding on

earlier work by Mawson (1987, 1999a, 1999b), facts and scholarly opinion from various

sources are summarized below that challenge the hypothesis of injurious intent as a general

explanation of inflicted injuries. Problems in establishing injurious intent are discussed

under the following headings:

1. Assaults are typically impulsive.

2. Self-injury is not attempted suicide.

3. Motives are often unclear to the perpetrator.

4. Violence often involves intimates.

5. Use of weapons does not necessarily imply murderous intent.

6. Many perpetrators are cognitively impaired.

4.1. Assaults are typically impulsive

Most assaults and killings that come before the courts result from impulsive actions

lacking carefully worked-out intentions (Prothrow-Stith & Weissman, 1993, pp. 17–24;

Briscoe, 1975). They tend to arise from trivial disputes, often against a background of severe

stress, intense emotion, and intoxication from alcohol and/or drugs, and are performed with

little thought in terms of motives or consequences. Many such injuries occur during

escalating conflicts or in the course of fighting, and are not intended. The presence of

alcohol and drugs ‘‘distorts’’ attitudes and behavior, cognition becomes impaired and normal

inhibitions are lost.

4.2. Self-injury is not attempted suicide

The highest rate of so-called ‘‘attempted suicide’’ occurs in women in their late teens. Most

are carried out on impulse, with less than an hour’s thought beforehand. People who have been

revived after apparent suicide attempts often thank their rescuers and carers; they deny

intending to kill or even harm themselves, claiming they had other intentions or motives, or

were uncertain of their intentions (Kessel, 1965). Instead of wanting to die, many want to forget

their problems; others want to be reborn, hoping for a new or improved quality of life (Simpson,

1976). Ideation connected with self-injury is notoriously vague in terms of desired outcomes

(Douglas, 1967) and ‘‘attempted suicide’’ is often amisnomer. These behaviors represent less of

a wish to die than an attempt to obtain help with interpersonal problems (Kreitman, Phillips,

Greer, & Bagley, 1969); indeed, the act may succeed, at least temporarily, in rallying such help.

Although some ‘‘attempters’’ commit suicide later on, most do not. Risk factors for early

reattempt include being over 45, living alone, alcoholism, being male, unemployed, making a

violent attempt, multiple previous attempts, and leaving a suicide note (Roy, 1996).

There is evidence that the wish or desire to die (or kill) is transitory (Clarke & Lester,

1989). Between 1963 and 1975, when suicide rates were increasing in most European

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countries, the suicide rate in England and Wales fell by 35%. This decline has been

attributed to the progressive reduction in carbon monoxide from the public gas supply

based on coal, and its replacement with less hazardous natural gas from the North Sea

(Hassall & Trethowan, 1972). Domestic gas accounted for over 40% of suicides in 1963,

but by 1975, this means of suicide was all but eliminated. However, in their analysis of

the ‘‘gas story,’’ Clarke and Mayhew (1988) noted that few of those prevented from

using gas to kill themselves found other ways to do so. These findings were interpreted

as suggesting that suicide is ‘‘an intentional act designed to bring an end to deep, though

sometimes transient despair, chosen. . .when the person has ready access to a means of

death that is neither too difficult nor repugnant’’ (Clarke & Mayhew, 1988). It is often

claimed that people really intent on killing themselves (or others) will find a way to do

it, but this natural experiment involving changes in the public gas supply in England

shows that such intentions are neither strong nor long lasting. The act may be described

after the fact as intentional, but the motivation is superficial and transient, and the urge

diminishes if the usual or desired means are unavailable. Opportunity is a major factor in

suicide and, by analogy, violent crime. As Clarke and Mayhew note, the declining

toxicity of domestic gas was not widely known. Hence, many people continued through

ignorance to ‘‘put their heads in the gas oven.’’ Why did the suicide rate decline? Some

of the more determined may have been unable to find an acceptable alternative means,

whereas others who were less determined may have been saved from death by deciding

that they were not meant to die, or found the help they needed. At any rate, the ‘‘urge to

die’’ passed for 35%.

Most homicides and assaults are likewise not the result of an inexorable drive to harm or

kill, but of impulsive behavior fueled by despair or some other intense emotion, together with

the availability of a weapon (Prothrow-Stith & Weissman, 1993).

4.3. Motives are often unclear to the perpetrator

It is frequently impossible to establish the existence of injurious intent in the mind of

perpetrators of interpersonal injury at the relevant moment (Earls, 1992). When questioned

after the event, many are unable to explain their behavior and deny injurious intent. For some,

this could reflect an understandable tendency to portray oneself in a favorable light and a

deliberate attempt to distort the truth. Such statements are usually taken as obvious attempts at

self-exoneration. But admitting injurious intent does not necessarily imply that it was present

before or at the moment of violence. Memories of alleged reasons for perpetrating injury are

notoriously subject to rationalization and distortion. People may admit to having injurious

intent, often to make sense of behavior that seemed inexplicable to them after the event,

especially under interrogation by a persistent or biased interviewer (Briscoe, 1975).

4.4. Violence often involves intimates

The hypothesis of injurious intent is inconsistent with the fact that perpetrators are often

deeply involved emotionally with their victims, and suicide after homicide is not uncommon.

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Violence typically involves people who are closely attached to each other (Mawson, 1980;

Meloy, 1998). It has been hypothesized that interpersonal violence, far from being intended to

cause injury, is often an expression of attachment behavior; that is, proximity-seeking

behavior designed to reestablish or reaffirm an intimate relationship (Mawson, 1980, 1987;

Meloy, 1998). With regard to fatal injuries, less than 1 in 6 (16%) of all homicides occur

during the commission of another crime. Homicide tends to involve family members or

friends and acquaintances, and both victim and assailant are of the same race in 90% of cases

(Prothrow-Stith & Weissman, 1993). A study of 50 individuals who had ‘‘stalked’’ their

victims before seriously injuring them, based on case files from a regional forensic service in

London, U.K., over a 5-year period, showed that in 70% of cases involving serious violence,

a previous sexual relationship existed between stalker and victim. Psychotic illness was much

more common in cases involving strangers (75% versus 20% in the former sexual intimacy

cases). The greatest danger of serious violence from stalkers was not from strangers or people

with psychotic illness but from nonpsychotic former partners (Farnham, James, & Cantrell,

2000). The overall risk of serious violence by stalkers is low (Tjaden & Thoennes, 1998).

A high proportion of hospital emergency department (ED) attendees have been injured

by intimates, including family members. About 50% of women visitors to EDs have

experienced violence at the hands of an intimate during their adult life (McCoy, 1996;

Schnitzer & Runyan, 1995). It is impossible to estimate the proportion of these injuries that

are intended to harm or kill. A high proportion of couples involved in domestic violence

stay together; indeed, the more severe a woman’s injuries, the longer she tends to remain

with her spouse (Pagelow, 1981). Following the killing of a loved one, grief can be so

intense that homicide is followed by suicide in the surviving partner in 4–42% of cases

(Coid, 1983; West, 1966).

Parents sometimes injure their children unwittingly in the course of trying to control or

discipline them. In such cases, the actions may be deliberate, for example, slapping, spanking,

or vigorous shaking, but the outcomes in terms of injury or death are seldom intended

(Mawson, 1999b). Injuries to children resulting from parental actions may be largely due to

the force of their movements and resulting energy exchanges that exceed the tolerance

threshold of the child’s body rather than to an intention to cause tissue damage. The

dichotomy of intentional and unintentional injury obscures the important distinction between

deliberate action that happens to cause injury (e.g., shaking, spanking), and actions performed

with the intention of causing injury. Parental blameworthiness for children’s injuries should

be considered more on a continuum rather than as intentional or otherwise. Identifying

preventive measures should also take precedence over assigning blame (Peterson & Brown,

1994; Peterson & Stern, 1997).

4.5. Use of weapons does not necessarily imply murderous intent

Another factor influencing the tendency to label injuries as intentional is the lethality of

the weapon involved, and hence the severity of injury. A high proportion of ‘‘intentional’’

deaths and injuries involve firearms, the typical homicide involving one or more armed

acquaintances who have been drinking and arguing. Because injuries resulting from guns or

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knives tend to be serious or fatal, they are presumed to be intentional. This confuses the

outcome of the behavior with its motivation. The intentions of people who point and

discharge firearms at others or themselves are considered self-evident, but surveys show

that the intentions of those who have injured or killed others by firearms are often unclear

and seldom intentional. One survey found that incarcerated felons who had inflicted

apparently deliberate gunshot wounds (Wright & Rossi, 1985) claimed that death or injury

was not their paramount intention. In most cases, triggers were pulled and firearms were

discharged either out of fear, to scare the victim, or to induce compliance. Injury and death

were largely unintended outcomes and were mainly due to the presence and use of lethal

weapons. Thus, an assailant who uses a gun appears to be no more intent on killing than

one who uses a knife, but guns are more lethal. Injury outcomes in terms of survival or

death are largely determined by the use and type of weapon involved (Prothrow-Stith &

Weissman, 1993, pp. 17–24).

4.6. Many perpetrators are cognitively impaired

Aggressive behavior that may or may not result in injury is ironically most common,

precisely among those whose ability to verbalize intentions is impaired, for example, those

with mental retardation and persons with organic diagnoses or traumatic brain injury

(Andrews, Rose, & Johnson, 1998; Miller, 1994; Thompson & Gray, 1994). Cognitive

deficits are also common among offenders in general (Moffitt & Lynam, 1994). A high

proportion of habitually violent individuals have medical histories suggesting serious brain

injury (Lewis, Lovely, & Yaeger, 1989). Many persons arrested for violence are also in a

dissociated mental state at the time of their offenses (Lewis, 1998; Lewis et al., 1989; Pincus,

1987). With regard to self-inflicted injury in nonmentally retarded individuals, self-injurers

are typically depressed and not fully aware of the implications of their actions in terms of

continued survival or death (Kessel, 1965; Simpson, 1976). Intent-to-injure is also inappro-

priate as an explanation of violence in the very young, because a child does not become fully

aware of the potential harm his or her behavior can cause until some years after the first

appearance of such behavior (Pettit, 1997).

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UNC5. Intentional and unintentional injury—are they really different?

Intentional and unintentional injuries are assumed to be distinct. Most motor-vehicle-

related deaths, for instance, are said to be unintentional, whereas most firearms-related deaths

are considered intentional and may be either self-directed or outwardly directed (Kraus et al.,

1998). As we have seen, however, the concept of intentional injury is problematic; it also

perpetuates an oversimplified view of both injurer and injured. The literature suggests that so-

called ‘‘intentional’’ and ‘‘unintentional injury’’ are closely related phenomena in that (1)

similar risk factors are involved, (2) people injured by assault are often perpetrators of injury

(i.e., they are self-injurers or have injured others), and (3) some individuals experience

multiple injuries of all kinds.

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5.1. Similar risk factors are involved in both types of injury

Similar factors and circumstances are associated with both unintentional and intentional

injury, such as alcohol/drug use, psychosocial stress, psychiatric disorder, and criminality

(Cohen et al., 2003).

Alcohol and illicit drug use are related to an increased risk of violent death in the home; the

risk of homicide is also increased for nonsubstance-abusing individuals living in households

where other members abuse drugs or alcohol (Rivara et al., 1997).

Cigarette smoking has been linked to a variety of unintentional injuries as well as

intentional injuries, such as suicide; risk taking has been suggested as a possible common

mechanism. Risk-taking tendencies are more frequent in smokers than nonsmokers;

smokers are less likely to wear seat belts and more likely to be rule breakers (Sacks &

Nelson, 1994). Indeed, risk-taking dispositions may be more important predictors of injury

than drinking or drug use (Cherpitel, 1999). Impulsivity and many drug-related behaviors

are associated with both types of injury (Hamburg, 1998).

A strong linear relationship has been found between antisocial (aggressive) behavior and

number of childhood injuries. The strongest behavioral predictor of medically treated injury is a

history of previous injury, followed by parent-reported oppositional behavior (Bijur, Golding,

& Haslum, 1988; Bijur, Stewart-Brown, & Butler, 1986; Bussing, Menvielle, & Zima, 1996;

Jaquess & Finney, 1994; Langley, McGee, Silva, & Williams, 1983). In a study of the

psychosocial characteristics of children with fractures (excluding battered children and those

with skull fractures, and using standardized instruments for which norms were available),

injured children had significantly higher scores for conduct and psychosomatic problems,

impulsivity, hyperactivity, and anxiety, based on parent ratings (Loder, Warchausky, Schwartz,

Hensinger, & Greenfield, 1995).

Many studies show that dangerous driving and motor vehicle crash injuries are associated

with problem drinking, substance abuse, promiscuity, and sexually transmitted disease

(Cherpitel, 1999; Jessor & Jessor, 1977; Willett, 1960). In a study of the role of alcohol

in fatal nontraffic injuries classified as intentional (i.e., homicide), unintentional, and suicide,

involving a meta-analysis of U.S. medical examiner reports published between 1975 and

1995, Smith, Branus, and Miller (1999) found that intoxication (blood alcohol concentration

z 100 mg/dl) was present in 32% of the homicide cases, 31% of the unintentional injury

cases, and 23% of the suicide cases.

5.2. People injured by assault are often perpetrators of injury (including self-injurers)

Victims and perpetrators of violence represent highly overlapping populations. As a general

rule, those at greatest risk of repeated or serious injury are likely to inflict injury on others. Such

individuals tend to be young adult males with a history of delinquent behavior (Earls, 1991).

Juvenile drug sellers are at particularly high risk for both perpetrating and being a victim of

violent crimes (Dembo, Hughes, Jackson, & Mieczkowski, 1993; Goldstein, 1985). Perpe-

trators and victims of criminal violence have many characteristics in common, including age,

male gender, race, and a previous criminal record. In his classic study of 588 recorded

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homicides in Philadelphia from 1947 to 1952, Wolfgang (1958) found that 26% were ‘‘victim-

precipitated’’ in that the victim was the first to use physical violence in the fatal confrontation.

Typically, a husband assaulted his wife and was then killed by her in the ensuing struggle. The

victims of these homicides tended to have previous arrest records, especially a record of assault.

Gayford (1975) studied 100 women victims of violence and their male perpetrators and found a

high frequency of suicide attempts, alcohol use, and explosive outbursts toward their children

on the part of the women.

Among adult male detainees in a large correctional center, 26% had sustained at least one

prior firearm injury, suggesting that the best predictor of violent victimization may be

involvement in the criminal justice system (May, Ferguson, Ferguson, & Cronin, 1995). This

was confirmed in a retrospective, matched case-control study (Mawson et al., 1996) on

behavioral risk factors for spinal cord injury, in which 140 spinal-cord-injured persons (about

half of whom were injured by firearms) were compared to driver’s license holders matched on

age, race, gender, zip code of residence, and education. Although the precise nature of their

offenses was unspecified, the spinal cord injured were significantly more likely than the

controls to have been arrested, convicted, and incarcerated before their spinal cord injury.

Rivara, Shepherd, Farrington, Richmond, and Cannon (1995) similarly found that people

attending EDs following assaultive injuries had a very high rate of prior convictions for

assault.

Victims and perpetrators of injury are closely overlapping populations, and chance factors

often determine who, in a fight, will be the victim (Wolfgang, 1958). Injury often occurs in a

social context in which two or more people are drawn together with similar underlying needs

and problems, and their mutual interaction escalates into violent situations in which either

person can be hurt. Usually, it is the female in a relationship who is actually injured, or

injured more severely, rather than the male (Centers for Disease Control and Prevention,

1996; Ernst et al., 1997).

5.3. Some individuals have been injured repeatedly in a variety of ways

Trauma has a high rate of recurrence, suggesting that some people are more injury

prone than others. To determine the degree of injury recidivism and to identify risk

factors, Williams, Furbee, Hungerford, and Prescott (1997) reviewed the records of

patients who presented for treatment of an injury at a rural Virginia ED. Injury recidivism

was defined as a patient who presented for treatment of two or more unique injuries

during the 1-year study period. Of 37,360 ED patient visits, 12,075 were injury related,

and of these 2838 (24%) involved injury recidivists. Among the injured patients, 12%

were recidivists. Degree of recidivism was inversely associated with age and positively

associated with Medicaid coverage and lack of other insurance. Recidivism was also

positively associated with intentional injury and inversely with transportation-related

injury. It was concluded that a small group of patients account for a significant proportion

of ED injury visits—a younger, lower SES group with an increased risk of intentional

injury. Heavy users of the ED represent a population that is both medically and socially

vulnerable.

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Repeat visitors to the ED for injury tend to young males with severe injury, among whom

African Americans are heavily overrepresented (Hedges et al., 1995). Most research work,

being based on patients with penetrating trauma or on data from injury registries, tends to

include only those with serious injuries. Hypothesizing that a more accurate assessment of

reinjury could be obtained by examining all injured patients presenting consecutively to an

ED, Madden, Garrett, Cole, Runge, and Porter (1997) studied patients presenting to an urban

ED with an injury over a 23-month period (1991–1992). The injured were followed

prospectively for 1 year from their index visit date. Of 34,000 patients totaling 45,000 visits

to the ED during the period of follow-up, 22% had a repeat injury in 1 year and the cohort

mean was 1.3 injuries per year. This mean was unaffected by race, age, gender or E-code. It

was concluded that the factors placing patients at risk for recurrent injury are not

demographic. Patients whose initial injuries were ‘‘intentional’’ had the highest mean rate

of repeat injury (a 30% reinjury rate versus 16% for motor-vehicle crashes).

In an interview study of 285 consecutive trauma patients, 22% had been treated in a

hospital for a total of 75 previous episodes of intentional trauma (mean, 1.3 episodes per

patient). Of these injuries, 5% had been treated in hospitals within a 10-mile radius of King/

Drew Medical Center, Los Angeles, and 65% of the episodes had occurred within 5 years or

less prior to the current injury (Kennedy, Brown, Brown, & Fleming, 1996). In a study

designed to estimate the risk and cost of rehospitalization due to intentional injury recidivism,

trauma admissions to the San Francisco General Hospital over a 3-year period were reviewed

involving youths under age 25 who were victims of gunshot wounds, assault, and stab

wounds. A total of 552 charts was reviewed after sampling every other chart. Of these

individuals, 87 (16%) had had a previous intentional injury, 94% within the previous 5 years,

and 44% of the injuries were due to firearms. There were 38 deaths, 92% of which were due

to firearms. Estimated costs of hospitalizations for these 552 youths for 3 years were US$3.8

million. It was concluded that intentional injury is a major risk factor for reinjury and a major

mechanism of intentional injury among youths involving firearms (Tellez, Mackenzie,

Morabito, Shagiury, & Heye, 1995).

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UNCO6. Injury is closely related to other health risk behaviors

Studies of persons who have experienced severe injury, whether inflicted or otherwise,

suggest that injury is part of a broader behavioral phenomenon or syndrome. Many injury

victims have histories of criminality, antisocial personality disorder (APD), substance abuse,

alcoholism, sexual promiscuity, and other psychosocial–behavioral difficulties; these char-

acteristics occur together so frequently that they can be said to form a behavioral syndrome,

of which, susceptibility to injury (as perpetrator and/or victim) is one manifestation.

6.1. Criminality

Criminality is closely related to ‘‘violent’’ injury as well as injury in general. In the study

of spinal-cord-injured persons and matching controls referred to above (Mawson et al., 1996),

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the spinal cord injured were 4.6 times more likely than the controls to have been arrested, 5.3

times more likely to have been convicted, and 31 times more likely to have been incarcerated

before their spinal cord injury. The spinal cord injured also had significantly increased scores

on Zuckerman’s (1979) Sensation-Seeking Scale compared to the controls, after controlling

for criminality and prior injury (odds ratio 2.05, 95% confidence interval 1.67–2.53). A study

in which hospitalization records were linked with juvenile justice records showed that

hospitalizations for injury were almost three times greater for male offenders and 1.6 times

higher for female offenders compared to nonoffenders (Conseur, Rivara, & Emanuel, 1997).

A study of almost 3000 young offenders in Victoria, Australia, over a 3-year period, showed

that male offenders were approximately 9 times and female offenders 40 times more likely to

die than the general population. Drug-related events, suicide, and unintentional injury were

the leading causes of death, and death rates in young offenders were higher than in equivalent

age groups with schizophrenia or eating disorders (Coffey, Veit, Wolfe, Cini, & Patton, 2003).

6.2. Alcoholism and APD

In a study of individuals diagnosed with APD and alcoholism, 58% had experienced a

significant head injury and 52% had a family history of problem drinking (Malloy, Noel,

Longbaugh, & Beattie, 1990). Exposure to violence is related to a constellation of associated

problems, including increases in weapon possession, depression, substance abuse, sexually

transmitted diseases, and becoming an adolescent parent (Singer, Anglin, Song, & Lunghofer,

1995). The association between alcohol abuse and trauma is well known. In a study of 18- to

20-year-olds admitted to a trauma center, 41% had been drinking. The association with

drinking was strongest for assault-related injury and 49% had evidence of chronic alcohol

abuse, as shown by high scores on the Short Michigan Alcohol Screening Test (Rivara et al.,

1992). Records of the Northern Finland 1966 Birth Cohort were examined to determine if age

at first conviction for drunk driving was associated with severe psychiatric morbidity or

violent criminality. Almost half the violent offenders with mental disorder committed their

first drunk-driving offense before age 18; the younger the driver, the more likely he was to be

violent and mentally ill (Rasanen, Hakko, & Jarvelin, 1999).

6.3. Delinquency, firearms injuries, sexual promiscuity, and suicidal gestures

A retrospective chart review of youths committed to Virginia juvenile correctional centers

(consisting almost exclusively of African American males), found that all of the sampled

delinquents (drug traffickers as well as delinquents who were not drug traffickers) had a

substantial history of firearm injuries (30% in both groups), self-reported promiscuity, and

suicidal gestures (McLaughlin et al., 1996).

Violent juveniles have many cooccurring problems, including problem alcohol and drug

use, a high percentage of externalizing symptoms on the Child Behavior Checklist, school

problems such as truancy, suspension, and dropping out, being a victim of violent crime, drug

selling, gang membership, and teenage parentage (Huizinga & Jakob-Chien, 1998). In the

Cambridge Study in Delinquent Development, violent offenders tended to be difficult to

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A.R. Mawson / Aggression and Violent Behavior xx (2004) xxx–xxx 15

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discipline, troublesome, and dishonest at 8–10 years of age; they were bullies, frequent liars,

and frequent truants at 12–14 years of age; and drug users, heavy drinkers, sexually

promiscuous, and frequently unemployed at age 18 (Farrington, 1998).

6.4. Suicidal attempt/self-injury

Suicidal attempt/self-injury is related to repeated injury, alcoholism, and substance abuse,

including heavy usage of cigarettes and coffee (Tanskanen et al., 2000). The relationship

between use of alcohol, cigarettes, coffee, and the risk of suicide was studied in 36,689 adults,

men and women, in Finland over 14 years. There were 169 suicides. Joint heavy use of all

three substances was rare, but the adjusted relative risk of suicide increased linearly with

increasing joint heavy use of alcohol, cigarettes, and coffee with joint heavy use of all three

substances; there was an almost fourfold increased risk of suicide (Adjusted Relative Risk

3.99; 95% CI 1.80, 8.84). It was concluded that clustering of heavy use of alcohol, cigarettes,

and coffee could serve as a new marker for increased risk of suicide.

6.5. Cigarette smoking

Cigarette smoking is associated with antisocial behavior, risk taking and impulsiveness, an

increased likelihood of divorce and of changing jobs, increased sexual activity, and increased

tea, coffee and alcohol consumption (U.S. Department of Health, Education and Welfare,

Public Health Service, 1979). Cigarette smoking is also associated with depression,

schizophrenia, anxiety disorders, and suicide (Giovino et al., 1995).

6.6. Substance abuse, alcohol, risk taking

Seriously injured patients in trauma centers commonly have associated problems, includ-

ing alcoholism and criminality. In one of many such studies, among 1118 unselected trauma

patients interviewed, 54% had a previous psychoactive substance abuse disorder, 24% were

currently alcohol dependent, and 18% were dependent on other drugs. Rates of drug

dependence were higher among nonwhite and victims of intentional injuries (Soderstrom

et al., 1997). In the 1995 National Alcohol Survey of almost 5000 respondents in the United

States, frequent self-reported drug use and the simultaneous use of alcohol and drugs were

directly related to injury. Risk-taking/impulsivity disposition variables (e.g., ‘‘I often act on

the spur of the moment without stopping to think’’) and sensation-seeking scores (Zucker-

man, 1979) were independently related to injury, and appeared to be more important

predictors than either drinking or drug use (Cherpitel, 1999).

One hundred unselected adolescent and young adult patients admitted to an urban trauma

center were interviewed using standardized instruments (89% of the injuries involved

interpersonal violence). Male gender, unemployment, past arrest, high levels of anger,

aggression, and thrill seeking (Adolescent Risk-Taking Instrument), previous criminal

victimization, use of weapons, fighting, and not having received counseling distinguished

those with firearm from other types of injuries. Use of alcohol on weekdays, past arrest, and

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risk-taking behavior were also associated with trauma recidivism (Redeker, Smeltzer,

Kirkpatrick, & Parchment, 1995). Major injury is also associated with unstable early home

life and poor socialization (Pless, Verreault, & Tennia, 1989), high ratings of impulsivity and

daring in childhood (Langley, Silva, & Williams, 1987), cigarette smoking, a history of

school failure (Kraus, Steele, Ghent, & Thompson, 1970), involvement with the criminal

justice system (Yaeger & Lewis, 1990), unemployment, multiple marriages, and illegitimate

children (Michalowski, 1977).

6.7. Bulimia nervosa

The central features of bulimia nervosa (BN)—binge eating and purging—have been

recognized for about 30 years (Kiss, 2000; Russell, 1979). Many studies have shown a close

association between eating disorders (especially BN), conduct disorder, depression, alcohol-

ism, substance abuse, criminality (including theft), physical violence, sexual activity, and

self-mutilation and suicide attempts (Baum & Goldner, 1995; Sinha & O’Malley, 2000).

6.8. Schizophrenia/severe mental illness

Increased rates of alcoholism, conduct disorder in childhood, and antisocial personality in

adulthood occur among relatives of people with schizophrenia. Reduced amplitude and

delayed latency of the P300 waveform (a positive event-related potential recorded across the

scalp about 300 ms after a random stimulus) is a common finding in schizophrenia,

alcoholism, and conduct disorder (Bauer & Hasselbrock, 1999; Blackwood, 2000). Depres-

sion and mania are very common in juvenile offenders. Among 50 child inmates ages 11–17

in an urban juvenile detention center, 10 (20%) met the criteria of mania and another 20% met

the criteria of major depressive disorder. Adolescents with mania had high rates of reported

substance abuse other than alcohol or marijuana (Pliszka, Sherman, Marrow, & Irick, 2000).

Higher rates of cigarette smoking and substance abuse (Dervaux et al., 2001; Itkin, Nemets,

& Einat, 2001; Walkup et al., 2001), traumatic brain injury (Malaspina et al., 2001), spinal

cord injury (Kennedy, Rogers, Speer, & Frankel, 1999), self-injury, and suicide (Radomsky,

Haas, Mann, & Sweeney, 1999) are reported in schizophrenics. People with mental disorders,

including severe mental illness, are also at increased risk of death by homicide (Hiroeh,

Appleby, Mortensen, & Dunn, 2001).

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UN7. Gradient of adversity

There is a gradient of adversity in the backgrounds of people who have been injured, with

a higher level in those with inflicted versus noninflicted injury. For instance, a much higher

proportion of those with assault-related injuries have criminal records than those injured

‘‘unintentionally’’ (Rivara et al., 1992). In a comparison of victims of intentional injury,

victims of nonintentional injury, and patients undergoing elective surgery, those with

intentional injuries had a higher probability of alcohol use, admitted illicit drug use, and

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PROOF

unemployment, and had a lower mean IQ score. In addition, 63% of the intentional cases met

the criteria for at least one category of psychopathology compared to 50% in the noninten-

tional injury group and 30% in the surgery group. Trauma was associated with younger age,

lower intelligence, antisocial personality, mental retardation, depression, and low income;

victims of inflicted trauma in particular had a high incidence of psychopathology, unemploy-

ment, alcohol abuse, and illicit drug use (Poole et al., 1997). Other risk factors for serious

injury or premature death from violence include youth, male gender, poverty, ethnic minority

status, and urban residence (Christoffel, 1990).

In summary, regardless of the type of problem behavior selected (whether injury, crime,

early-onset alcoholism, substance abuse, eating disorders, multiple sex partners, unsafe sex,

etc.), one encounters a similar pattern of interrelated behaviors and background factors

(Cloninger, Sigvardsson, & Bohman, 1988; Farrington, 1995; Knop, Jensen, & Mortensen,

1998; Regier et al., 1990; Robins, 1978; Tarter & Edwards, 1988; Vaglum, 1998; Yee, Castro,

Hammond, John, Wyatt, & Young, 1995). As noted, high-risk behaviors for injury, such as

alcohol and drug abuse, unsafe sex, and violence, frequently cluster in a syndrome. What,

then, is the nature of this postulated behavioral syndrome, and is the quest to understand

injury-related behavior a reasonable one?

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UNCORRECTE8. Searching for the causes of injury—reasonable or futile?

While acknowledging that injury is associated with behavior problems, Rivara (1995)

considers that problem behaviors are only weakly associated with injury and therefore of

limited usefulness in predicting injury; moreover, even if injury-prone children or adults

could be identified in advance, they would make up a very small proportion of the injured as a

whole. Correction of these problems would therefore have little impact on the overall rate of

injury. The focus of preventive efforts should instead be on correcting hazards in the

environment.

The need nonetheless remains to understand and prevent injury in those at high risk,

especially as a significant minority of individuals experience repeated injury. Although injury

is uncommon in people’s lives compared to chronic substance or alcohol misuse, the close

association between the latter behaviors and injury suggests that susceptibility to injury is part

of a wider behavioral syndrome. Understanding the nature of this syndrome could prove to be

a more useful approach to correcting the behavior of the injury prone than attempting to

screen for and prevent injury-related behavior directly; that is, successful treatment of one

aspect of the syndrome would be expected to lower the risk of other aspects of the syndrome,

including injury.

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9. A continuum of self-destructiveness?

One recent hypothesis to explain the pattern of risk factors for intentional injury is that

people who engage in these behaviors range from being partially intent (‘‘subintentional’’)

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to being fully intent on self-destruction (Neeleman, Wessely, & Wadsworth, 1998). People

at high risk of suicide (i.e., those who have previously attempted suicide, people with

mental illness, substance misusers, and people who have undergone psychiatric treatment as

children) are also at increased risk of premature natural and accidental death. This has

suggested a causal continuum between behaviors that are indirectly self-destructive and that

shorten life regardless of suicidal motivation or thoughts (e.g., alcoholism, cigarette

smoking, overeating, and dangerous driving), and overt suicidal behavior. Noting that

evidence for the continuum is only circumstantial, Neeleman et al. (1998) studied the links

between childhood and adolescent temperament and behavior and the risk of natural,

accidental, and suicidal death between ages 16 and 50. Data were obtained from the U.K.

Medical Research Council’s National Survey of Health and Development, a stratified

random sample (n = 5362) of 13,687 births in the U.K. during 1 week in March 1946.

Complete data were available on 3591 individuals. Links were examined between

prospectively collected data on childhood and adolescent temperament and behavioral

factors and premature death. A panel of psychiatrists scored deaths on the likelihood of

suicidal intent. These scores were used in a weighted logistic regression analysis to

determine independence of risk factors for the hypothesized continuum of subintentional

to intentional self-destruction. Of the 167 premature deaths in the group, 150 were

classified as due to natural causes, 6 as accidental, and 11 as suicides. Factors linked to

suicide, such as nocturnal enuresis, poor physical development, aggression, conduct

disorder, low anxiety, and emotional instability, were also associated with an increased

risk of accidental death. Some of the factors common to suicide and accidental death, such

as poor adolescent physical development, conduct disorder, lower parental social class, and

poor academic achievement, were also associated with an increased risk of natural death

and premature mortality in general (weakly with natural death, more strongly with

accidental death, and most strongly with suicide). Poor physical development and low

weight gain are known risk factors for future suicide (Barker, Osmond, Rodin, Fall, &

Winter, 1995). Neeleman et al. concluded that their findings of a close relationship between

various forms and causes of premature death related to violence were consistent with the

hypothesis of a continuum between subintentional and intentional self-destructive behavior.

The fact that suicide shares some of its main risk factors with alternative causes of death

also indicates that suicide is not an isolated phenomenon but is intimately related to

‘‘accidental’’ and premature natural death.

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UN10. Toward a new model for understanding injury

What is the nature of the behavioral syndrome? Is it most usefully explained in terms of

a continuum of subintentional to intentional self-destructiveness, as suggested by Neeleman

et al.? Does the association between suicide and accidental death suggest a general death

wish—an incipient tendency toward self destruction? As we have seen, a major difficulty

with these theories is that injurious intent—intentional or subintentional—can rarely be

ascertained on the basis of the available data. Severe injury or death may result from

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behavior, but these outcomes are seldom the subject’s expressed intention. There is,

nevertheless, a compulsive and directional element in injury behavior, and this element

is also seen in a variety of other behaviors that are closely correlated with ‘‘intentional

injury,’’ suggesting a common etiology. Following earlier work by Mawson (1987, 1996,

1999a, 1999b, 1999c), it is proposed that the underlying basis of the behavioral syndrome

is an exaggerated expression of an evolutionary-adaptive drive for sensory stimulation, and

that self- or other-directed injury in particular represents an intense, momentary expression

of SSB. SSB increases the probability of injury to self or others either directly or indirectly,

by a variety of routes, such as shooting, stabbing, drug–alcohol consumption and

intoxication, and/or drug overdose (see Fig. 1).

Intense SSB increases the risk of involvement in a variety of health risk behaviors (e.g.,

alcoholism, substance abuse, criminality, and eating disorders). These behaviors in turn

increase the risk of experiencing or inflicting injury. Consider, for example, assault, which

is viewed as an expression of intentional injury, that is, as aggression. When Person X

punches, kicks, stabs, or shoots Person Y, it is commonly assumed that X is deliberately

trying to do something to Y; namely, to harm or injure him. However, like the famous

ambiguous picture that can be viewed as either a vase or as two faces in profile, the

behavior can also be interpreted as an attempt by Person X to obtain something from

Person Y; namely, intense sensory stimulation via vigorous bodily contact. On the author’s

view, the biologic goal of the behavior is sensory stimulation, whereas injury, for the most

part, is a fortuitous consequence of the behavior or, more precisely, the result of exchanges

of mechanical or other types of energy that exceed the body’s tolerance threshold for injury

(Mawson, 1987, 1999a, 1999b). The need for sensory stimulation would not be recogniz-

able, of course, at the level of the conscious reasons and motives held by individuals in any

given situation.

UNCORR

Fig. 1. Toward a theory of injury causation. Proposed relationship between SSB and the behavioral syndrome,

including injury.

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11. Stimulation-seeking behavior

The concept of SSB derives from experiments begun half a century ago showing that

humans and many other species actively seek various forms of sensory stimulation; that

stimulation is often preferred to conventional rewards, such as food, water and sex; and that

prolonged sensory restriction produces neurophysiological deficits and retarded growth,

while certain forms of stimulation can correct or offset these deficits and enhance develop-

ment (Dieter, Field, Hernandez-Reif, Emory, & Redzepi, 2003; Field et al., 1986; Kuhn &

Schanberg, 1998; Riesen, 1975). To this day, the question remains unresolved of whether

SSB is a new drive, a personality trait involving thrill seeking, novelty seeking, or risk taking

(Cloninger, 1987; Zuckerman, 1994) or a more fundamental aspect of all motor–motiva-

tional behavior.

Our suggestion is that stimulation seeking is a tropism-like response inherent in motor–

motivational behavior and forms the substrate for all forms of interactional commerce with

the environment. The term tropism refers to an active orientational and directional process

involving movement of the organism as a whole towards sources of energy (Loeb, 1917/

1973). Well-known examples of tropisms are the tendency of plant leaves and stems to bend

toward the light (phototropism) and of roots to push toward the earth (geotropism). SSB is

defined by the author as any activity that enhances or facilitates contact between an

organism’s sensory receptors and environmental objects or surfaces (Mawson, 1978,

1999b). SSB comprises a spectrum of intensity of movement of the body as a whole towards

external sources of stimulation, as well participation by the peripheral sensory organs and

receptors in facilitating the reception of sensory stimulation (e.g., via pupillary dilatation,

nasal flaring, and increased skin conductance). It is postulated that behaviors, such as eating,

drinking, sexual activity, and aggression, represent overlapping bands on a continuous

spectrum of SSB, and that nutritional, reproductive, and other needs are fulfilled indirectly

as a result of seeking and obtaining stimulation. On the proposed model, hyperactivity,

agitation, mania, aggression, and other rage-associated behaviors represent overlapping bands

on a continuum of SSB, with apparently deliberate, intense, and highly directed manifes-

tations of SSB (‘‘aggression’’) at the upper end of the spectrum. The author hypothesizes that

SSB is part of a negative feedback system in which the sensory stimulation is fed back into

the central nervous system where it activates neurotransmitter systems that in turn inhibit

those responsible for SSB (see below; Mawson, 1987, 1999b).

The model predicts that individuals with a tendency toward one type of intense SSB are

likely to have problems with other types. Consistent with this hypothesis, a strong association

exists between multiple forms of impulsive behavior (Lacey, 1993), including criminality,

conduct disorder, alcohol and illicit drug use, eating disorders, precocious or hyper sexuality,

attention and hyperactivity disorders, as well as various aspects of injury, including self-

injury/suicide, assault/homicide, and many ‘‘unintentional’’ injuries such as motor vehicle

crash injuries; and we have suggested that they form a behavioral syndrome. Here, it is

proposed that all of these outcomes result from intense SSB, and that susceptibility to injury

results directly or indirectly, by many circuitous routes, from excessive SSBs, such as

physical violence/aggression, alcohol consumption, and/or drug overdose. Intense SSB

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A.R. Mawson / Aggression and Violent Behavior xx (2004) xxx–xxx 21

(especially where weapons are involved) coupled with mild cognitive impairment, impul-

sivity, and distractibility, heightens the risk of injury to oneself or others.

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12. Implications for practice

The stimulation-seeking hypothesis suggests novel ways of intervening to prevent injury

both at the individual and community level. It suggests that physical violence and related,

unwanted forms of SSB (all of which contribute to an increased risk of injury) could be

controlled by providing alternative forms of stimulation to substitute for that obtained in

harmful or destructive ways. The use of frequent and intense but nonpainful forms of sensory

stimulation could substitute for that obtained by violence or other behaviors related to

cravings and compulsions. In support of this hypothesis, there is evidence that both active and

passive forms of stimulation—including physical exercise, massage, and acupuncture—have

a generalized calming effect and can reduce behavioral problems, such as conduct disorder,

hyperactivity, and drug use (Field, 1995; Mawson, 1999b; NIH Consensus Conference

Acupuncture, 1998; Yoshimoto et al., 2001), as well as enhance well-being, self-concept

(Steptoe & Butler, 1996), and mood in incarcerated adolescents (MacMahon & Gross, 1988).

Field (2002) has noted that massage therapy decreases aggression and increases empathic

behavior in violent adolescents, and she suggests that this form of physical stimulation may

be effective by reducing dopamine and increasing brain serotonin levels.

Sensory stimulation could also be enhanced in many ways on a community-wide level. For

instance, school gyms could be opened at night to provide opportunities for youth to

experience nonharmful forms of intense sensory stimulation, such as music, dance, and

sports. The percentage of high school students who are physically active more than 20 min

daily in PE classes declined from 34.2% in 1991 to 21.7% in 1997 (Lowry, Wechler, Kann, &

Collins, 2001). For those at high risk, therapeutic interventions could be developed that

would combine various active and passive forms of social and physical stimulation, such as

massage, physical exercise, and participation in social support groups.

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UNC13. Research needs

Several major issues remain unresolved. First, how do alcohol and drugs operate as

cofactors in injury? Second, what are the physiological antecedents of SSB, leading to

different manifestations of the behavioral syndrome? After decades of research, it is still

unclear how alcohol and certain forms of drug intoxication increase the risk of injury and

violence (Giancola, 2004). On the one hand, alcohol and drug seeking are expressions of SSB

and thus form part of the behavioral syndrome. On the other hand, consumption of alcohol can

facilitate SSB (Moeller & Dougherty, 2001). What is needed is a means of blocking the

intoxicating effects of alcohol to prevent the resulting risks of injury to self or others. The

physiological basis of SSB is linked to alterations in brain dopaminergic activity, which is

usually considered inversely related to serotonin (5-HT; Cloninger, 1995; Mawson, 1999b;

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A.R. Mawson / Aggression and Violent Behavior xx (2004) xxx–xxx22

F

Quay, 1993). Low brain 5-HT is associated with bulimia, assault, suicide, and other aspects of

the behavioral syndrome, and may be part of the explanation for susceptibility to injury both in

humans and other primates (Higley et al., 1996; Spreux-Varoquaux et al., 2001; Twitchell et

al., 2001; Walsh & Dinan, 2001). There is also growing evidence that low total cholesterol

levels (and/or high-density lipoprotein levels) are related to violent outcomes (Golomb,

Stattin, & Mednick, 2000; Muldoon, Manuck, Mendelsohn, Kaplan, & Belle, 2001). These

and other factors could be combined in a prevention-oriented health-risk diagnostic assessment

tool for the behavioral syndrome.

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14. Summary and conclusions

Against the concept of an accident, which implies randomness and unpredictability,

William Haddon and others taught that injuries are predictable and preventable events

resulting from exchanges of mechanical and other forms of energy that exceed the body’s

tolerance threshold. This led to a new approach to injury prevention. Rather than

focusing exclusively on the difficult task of changing people’s behavior by educational

means, the new emphasis was on changing the environment so as to prevent injury in the

general population. However, in addition to reducing situational opportunities for injury,

the need remains to understand the biopsychosocial basis of susceptibility to injury.

While violence-related injury is increasingly viewed as a health issue, the residual

distinction between intentional and unintentional injury hinders the development of a

comprehensive public health approach to the problem. Not only are there many

similarities between so-called intentional and unintentional injury (Cohen et al., 2003),

but the concept of intentional injury demonizes and fosters a retributive attitude towards

the perpetrators of interpersonal violence as it did in the past toward suicide, because it

assumes that inflicted injuries are intentional. The distinction between intentional and

unintentional injury is unhelpful, and it ignores the extensive pattern of comorbidity that

characterizes a high proportion of adults and children who are injured in various ways.

Instead of classifying injury on the basis of intentionality, we should refer to noninflicted

injury and two kinds of inflicted injury, that is, self-inflicted injury and injury inflicted by

others (interpersonal injury). The distinction between injury-to-self or others is not

without problems (e.g., it is not always clear in practice), but it identifies in most

(but by no means all) cases the source of the injury, and at the same time leaves open

the question of motivation, thus providing a neutral way of describing the event and its

outcome.

The model proposes that the underlying motivation in self-inflicted and interpersonal

injury is not injury or death per se but intense sensory stimulation, either from direct

physical contact with the object of the behavior, or indirectly via the use of weapons. Injury

or deaths are usually fortuitous consequences of behavior and/or weapons, not its objective.

By reinterpreting physical (‘‘intentional’’) violence as a result of intense SSB, which may

lead to and be further heightened by drug or alcohol consumption, a more humane and less

judgmental attitude can be adopted toward those who inflict injury. The hypothesis of SSB

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A.R. Mawson / Aggression and Violent Behavior xx (2004) xxx–xxx 23

RECTED PROOF

suggests that the behavioral syndrome as a whole (including injury susceptibility) could be

treated by providing high-risk subjects with opportunities for alternative forms of intense

but nonharmful forms of sensory stimulation to substitute for that obtained in harmful

ways.

Interpersonal injury often occurs against a background of intense SSB directed towards

attachment figures. The injurer tends to be deeply jealous and protective of his relation-

ship with the victim, the pair having a symbiotic relationship that may extend to the entire

family (Mawson, 1980, 1987; Meloy, 1998). The outcome of physical violence (SSB) can

be deadly, but the latter is seldom intended. As a result of excessive SSB directed at an

intimate partner, the perpetrator often deprives himself of the very thing he most needs

and seeks: namely, close physical contact and continuation of the relationship. Interven-

tions for intimate partner violence could be developed and evaluated in which, for

instance, the partners engage in vigorous physical exercise and in whole body mutual

massage.

Interventions at the behavioral level currently favor educational approaches rooted in

exhortations to respect one’s peers and/or teachers. In many instances, however, as noted,

the subject and object of violence are intimates, and injury is unintended. The underlying

problem is not so much one of destructive intentions on the part of evil people, but of

stress-induced SSB combined with alcohol or drugs and the easy availability of weapons.

It has been proposed that lethal violence in schools and other places where people

congregate could be prevented to a great extent by entry-based weapons screening

(Mawson, Lapsley, Hoffman, & Guignard, 2002), thus making weapons unavailable or

inaccessible, and by other environmental modifications. The model also suggests that the

behavioral syndrome could be ameliorated or controlled by the provision of alternative

forms of sensory stimulation to substitute for that obtained in potentially destructive

ways.

In summary, the main theses of the paper are as follows:

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UNCOR(1) The dichotomy of intentional and unintentional is not a useful way of classifying severe

injury.(2) Injury is one aspect of a broader pattern of comorbidity (a ‘‘behavioral syndrome’’)

that includes criminality, alcoholism, eating disorders, and substance abuse, with a

shared underlying etiopathogenesis related to heightened stimulation-seeking

tendencies.(3) While instances clearly exist of truly intentional injuries and deaths (and we have no wish

to downplay in any way the consequences of injury for the injured), the purpose of this

paper has been to outline a new approach to understanding injury within its wider

psychobiological and social context.(4) Focusing on the destructive/injurious and allegedly intentional part of the outcome should

give way to understanding it in terms of a the spectrum of premature death and injury, of

which self-inflicted death (suicide) is one aspect. The suggestion is that injury is often a

consequence of a behavioral syndrome that reflects an intense need for sensory

stimulation.

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