The development of procedural knowledge in adults engaged in a “tractor-trailer” task

Cognitive Development, 9, 103-130 (1994)

The Development of Procedural Knowledge in Adults Engaged in a “Tractor-Trailer” Task

Nelson Moses

Long Island University

The purpose of this research was to study the development of procedural knowl-

edge in adults engaged in a novel task. Seven men and 7 women, aged 18 to 35

years, were presented a pivoting, steerable, toy tractor-trailer rig to back up, turn

90”, and park along a demarcated roadway. Their physical actions and comments

were examined in detail. Results revealed three phases of development in sub-

jects’ knowledge of steering procedures and the rig’s movement patterns, and in

their use of feedback information. A single transformation was observed in the

development of subjects’ knowledge of task demands. Subjects also manifested

different levels of functioning when addressing different task demands. These

findings were discussed in terms of transformations in organization that shape

development in the course of a problem-solving experience, and the role that

across-modality representation, feedback, error, and knowledge of task demands

play in such transformations. Furthermore, several differences that were observed

between men and women and among individual subjects were considered.

Procedural knowledge has received much attention recently as a complex aspect of cognition that is implicated in a broad range of human behavior (e.g., Bymes, 1992; Inhelder & Piaget, 1980; Karmiloff-Smith, 1986a, 1991; Metz, 1985; Newell, 1981). The term procedural knowledge refers to how individuals, upon reflection, represent to themselves procedures for achieving a task or solving a problem-that is, an individual’s conscious knowledge of problem-solving procedures.

This definition elaborates upon Byrnes’s (1992) description of procedural knowledge as “the knowledge of the steps required to achieve specific goals” (p. 235). The definition was influenced by Genevan research on developments in

Portions of this research were presented at the 20th Annual Symposium of the Jean Piaget Soci- ety, Philadelphia, June 1990. This research was funded in part by the Rutgers University Research

Council and partially conducted at Rutgers University, Department of Speech and Hearing Sciences,

New Brunswick, NJ. I wish to thank Elaine K. Altman, Philip Lewin, Harriet B. Klein, and an anonymous reader of an earlier version of this article for their valuable suggestions; Kim Carlson,

Lisa Palmieri, and Michelle Perkinson for their help with the videotapes; and Stephen A. Coynes for

drawing Figures 1, 2, and 3.

Correspondence and requests for reprints should be sent to Nelson Moses, Long Island Univer-

sity, Division of Education, 1 University Plaza, M205, Brooklyn, NY 11201.

Manuscript received December 1, 1991; revision accepted June 25, 1993 103

104 N. Moses

cognition that may be observed in the microanalysis of an individual’s discovery of problem solutions (e.g., Inhelder et al., 1976; Piaget, 1978). Studies of procedural knowledge that have emerged from this literature identified different levels and types of “knowing” about procedures, including knowing that is not conscious (e.g., sensorimotor know-how, exemplified in an infant’s handling of a bottle, or syntactic rules inherent in well-formed sentences). Much of this research endeavored to explain how conscious knowledge of procedures is achieved and transformed and eventually affects physical action (e.g., Blanchet, 1981, 1983; Karmiloff-Smith, 1986b, 1991; Wansart, 1990). Alternate ap- proaches to the study of procedural knowledge include examinations of how framing a current problem with reference to past problem-solving experiences affects the selection of applicable procedures (e.g., Greeno, 1983; Metz, 1985; Newell, 198 l), and how knowing core concepts about objects being manipulated (e.g., attributes, functions) facilitates the acquisition of procedural knowledge (Byrnes, 1992).

In light of traditional Piagetian cognitive-stage theories (e.g., Neimark, 1979; Piaget & Inhelder, 1969), one might expect that a stable developmental founda- tion for representing solutions to problems is established by adulthood. Advances in cognitive-stage theory along epigenetic lines (e.g., Case, 1985; Fischer, 1980; Granott-Farber, 1990; Karmiloff-Smith, 1986a), stimulated by the Genevan problem-solving studies cited earlier, suggest that procedural knowledge in adults be viewed from a more dynamic perspective.

Fischer and Bide11 (1991) defined the term epigenesis as signifying development that is constrained by: (a) genetic endowment, (b) environment (both social and physical), and (c) self-regulation of the organism (see also Carey & Gelman, 199 1; Granott, 1993; Granott-Farber, 1990). According to Fischer and Bidell, “in epigenesis, development is not reduced to any one of these factors but is analyzed in terms of the collaboration among them” (p. 201).

Studies of procedural knowledge that have been framed by the concept of epigenesis concentrated, primarily, on children and adolescents engaged in action-oriented tasks, such as learning how to resolve the Hanoi Tower Task (Wansart, 1990) and analogous problems involving trains and puzzles (Blanchet, 1981). This research suggests that the interaction among genetic, environmental, and self-regulatory influences is reflected in the context-sensitive nature of procedural knowledge. There appear to be two facets of context sensitivity. One entails a fundamental series of transformations in organization (e.g., Case, 1985; Fischer, 1980) or sequence of “phase-like processes” (Karmiloff-Smith, 1986a, 199 1) which may recur across the lifespan when individuals encounter new problems, and as different aspects of a system of procedural knowledge develop (see also Campbell & Bickhard, 1992). A second facet involves the imprint of task- specific characteristics and individual variation on developmental transforma-

tions (Feldman, 1988, 1993). How to characterize adults’ procedural knowledge in epigenetic terms is not

Procedural Knowledge in Adults 105

clear at the present time. Epigenetic models of development that have Piagetian roots are based primarily on research with children. Historically, the principal focus of Piagetian research with adults has been cognitive functioning at one point in time on conservation and formal-reasoning tasks (e.g., Bymes, 1988; Inhelder & Piaget, 19.58; Neimark, 1979). It is relevant to the present research on context-sensitive aspects of cognition that immaturities in adults’ cognitive functioning were identified in many of these earlier studies (e.g., Delisi & Staudt, 1980; Hooper, Hooper, & Colbert, 1985; McGillicudy-Delisi, Delisi, & Youniss, 1978; Murray & Armstrong, 1978).

Several of the developmental models that have been applied to children con- tributed to the creation of a framework for the present study of procedural knowledge in adults. Two related models are Werner and Kaplan’s (1964) paradigmatic theory of symbol formation and Fischer’s (1980) skill theory. According to Werner and Kaplan, initially holistic representations of problem-solving procedures undergo diRerentiation, reorganization, and integration in the course of development. Fischer described a recurring four-level cycle in the development of cognitive skills-that is, units of problem-solving behavior. Cognitive skills may be expressed as sensorimotor actions (e.g., shaking a rattle), simple representations (e.g., pretending to push a button), or more abstract conceptualiza- tions (e.g., envisioning functional relations among variables). Cognitive skills have an identifiable scheme-like structure and can involve some degree of awareness. The achievement of higher level skills is a consequence of the individual’s discovery, combination, integration, and intercoordination of constituent skills. Fischer (1989) emphasized that relatively subtle changes in task conditions, such as a shift from verbal description to physical execution of procedures, can impact upon the level of performance manifested by the individual.

Werner and Kaplan (1964) and Fischer (1980) each adopted the Piagetian principle that developmental achievements derive from sensorimotor action. Ac- cording to Piaget’s (1985) equilibration theory, awareness and elaborated organization are products of reflective abstraction, a process involving the projection of feedback information generated by sensorimotor behavior to higher levels of thought (see also Mounoud & Hauert, 1982; Piaget, 1971, 1977, 1978).

An alternative description of development, which borrows from modular theories of learning, was proposed by Karmiloff-Smith (1986a, 1991). Karmiloff- Smith applied this framework to children’s acquisition of procedural knowledge in tasks such as board-balancing, which involve the use of concrete objects (e.g., Karmiloff-Smith & Inhelder, 1975). She also applied this framework to the formation of metalinguistic knowledge (e.g., Karmiloff-Smith, 1986b). According to this model, the development of procedural knowledge proceeds through multiple phases as the problem solver automatically re-represents earlier representations of successful procedures.

initially, problem-solving procedures may be cognitively impenetrable (i.e., not accessible to consciousness), resistant to some forms of representation (e.g.,

106 N. Moses

verbal), and obligated to run in a fixed sequence. Several intermediate redescriptions yield representations of procedures that are accessible to consciousness and verbal expression, but may omit features of successful procedures exhibited at earlier developmental phases. Karmiloff-Smith (1986b) characterized such constructs as efforts to “simplify, unify, and have control over internal representations” (p. 174). Further redescriptions yield declarative-like knowledge of a more complete system of procedures accessible to a variety of representational modalities (e.g., kinaesthetic, visual, verbal). In the course of this re-representation process, knowledge in the mind acquires the status of knowledge to other parts of the mind (Karmiloff-Smith, 1991). In other words, procedures represented modularly become accessible to representation across modalities.

Despite differences in focus, the developmental models previously reviewed are not mutually exclusive. Each is suggestive of processes that may be implicated in context-specific developments in adults’ procedural knowledge. It is possible that adults, equipped as they are with relatively mature neurological systems, apply a variety of modalities (e.g., sensorimotor, verbal) to the representation of solutions to novel problems (T.R. Bidell, personal communication, June 3, 1991). It is possible, too, that the evolution of procedural knowledge in this process is subject to the differentiation and reorganization of schemes of action intrinsic to the structure of behavior within and across modalities (cf. Fischer, 1980; Werner & Kaplan, 1964), the stabilization of fluctuations in performance related to changing task conditions, and the use of feedback information. With reference to performance fluctuations and feedback, it is relevant that the ability to anticipate and regulate a variable stream of feedback information is characteristic of advanced levels of problem solving in action-oriented tasks (e.g., Blanchet, 1983; Karmiloff-Smith, 1986b; Wansart, 1990).

In a number of studies, the individual’s cognizance of the demands of a task has been identified as playing a central role in the development of procedural knowledge (e.g., Blanchet, 1983; Case, 1985; Galambos, 1986; Wansart, 1990). Task demands are intermediate goals that need to be identified and addressed in order to accomplish an overall task. Blanchet (1983) and Wansart (1984, 1990) proposed that the development of units of meaning relevant to procedural knowledge involves the representation and systematic organization of goals, subgoals, and the necessary causal transformations required to achieve envisioned goal states. Case suggested that knowledge about intermediate goals may serve as a framework for processing the ongoing flow of feedback from personal behavior and from objects being manipulated in the course of problem solving.

The purpose of the present research was to study the development of procedural knowledge in 14 adults engaged in a novel, concrete, and potentially problematic task-learning how to back-up, turn, and park a steerable toy tractor-trailer rig. This research should shed light on several theoretical issues concerning context-specific developments in the procedural knowledge of adults including the specification of transformations in organization that shape develop-


ment in the course of a problem-solving experience and the role that across-

modality representation, feedback, error, and knowledge of task demands might play in such transformations. Specifically, the physical actions and comments of the subjects were examined in detail to identify phases in the development of procedural knowledge, describe these phases in terms of inherent organization, and evaluate developmental differences among subjects.

METHOD

Subjects Seven men and 7 women, aged 18 to 3.5 years, participated as subjects. These were student volunteers from the Department of Speech, Language, and Hearing Sciences at Rutgers University. All subjects were licensed drivers. One male subject reported having driven a car with a boat trailer attached to it.

Data Collection

Tusk. Subjects were presented a steerable toy tractor-trailer rig which was positioned on one of two intersecting roadways outlined on a carpeted table (see Figure 1). The rig comprised a steerable toy tractor (25 cm X 12 cm) hitched to a trailer (30 cm X 14 cm). The connection allowed the trailer to pivot. Subjects had to steer the rig backwards along a roadway (150 cm X 35 cm) and while doing so, turn it 90” onto an intersecting roadway (60 cm X 90 cm) and park it along a demarcated area. Subjects steered the rig by maneuvering the steering

R

Figure 1. Dimensions and set up of the tractor-trailer task.

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Figure 2. Solution to the tractor-trailer task.

wheel on the tractor, which made the front wheels of the tractor turn on their axle. Because the steering wheel measures 1 in. (2.54 cm) in diameter, the most natural way to maneuver it is to grasp it with one hand between the thumb, index, and middle fingers and gently pull back. Figure 2 depicts the solution to the problem.

Two attributes of the tractor-trailer task make it particularly well suited for studying the research questions. First, characteristics of the task impose complex representational demands on the subject (see Metz, 1985). These demands are a consequence of interactions among a number of variables, especially task demands, steering actions, and the vehicles’ oppositional response pattern. (When backed-up, the tractor and trailer appear to turn in opposite directions.)

Second, the trailer’s oppositional response to steering is similar to movement patterns created by adults in simpler contexts-for example, when aligning an eating utensil in a place-setting by pushing on the side of one end. Such move-


ment patterns are a consequence of resistance at one end of an object to the

trajectory of a push on the other end (e.g., resistance from the trailer’s wheels pressing against the ground to the tractor’s push on the trailer’s hitch-end). Piaget and Garcia (1974) employed this dynamic in a simpler task to study children’s representation of directionality and understanding of causality. In that study, subjects were asked to anticipate and explain the movement of a rod being pushed on one end by another rod positioned perpendicular to it. The embedding of a com- monly produced effect in a more complex task should allow conclusions to be drawn about the relevance of past problem-solving experiences in novel task contexts (Fischer, 1989).

ExaminerlSubjectlTaskInteractions. Drawing from clinical interview techniques in Piagetian-based studies of problem solving (e.g., Hardiman, Pollatsek, & Well, 1986; Wansart, 1990), a protocol for interacting with subjects was for- mulated with reference to the purposes of the present study and characteristics of the tractor-trailer task. This protocol was more structured than the traditional Piagetian interview technique of critical exploration (Bovet, 1981). Subjects were presented the tractor-trailer in the “begin” position and were told that they had to steer the rig backwards and park it at the “end” position (see Figure 1). Each subject was allowed to interact spontaneously with the material. Before the first trial of each session, the investigator asked subjects: “How do you plan to do this?’ Intermittently thereafter at trial junctures (i.e., in between two successive trials), the investigator asked subjects to describe how they were planning to achieve the task or what they had just done. If a subject described a turning procedure, the examiner asked the subject to specify (verbally or by pointing) the direction that the trailer would move in response to the steering procedure described. The examiner did so as follows: “You say you’re going to turn the steering wheel this way. Which way is the trailer going to go?’ If a subject was having a persistent problem achieving the task, the examiner asked, “What do you think the problem is?’ If a subject made an unclear reference, the investigator asked for clarification in a nondirective manner. For example, one subject explained that she was planning to “cut the wheels the same way.” It was not clear what the “same way” referred to, so the investigator asked, “What do you mean by that?” Sometimes a subject held the steering wheel in an inappropriate position and forcibly skidded the rig into a desired position, not allowing it to roll freely. At the end of such a trial, the examiner alerted the subject to skidding, and told the subject to gently roll the tractor back next time.

Two additional complementary instructions were given to subjects. First, subjects were not permitted to manipulate the rig when answering the investigator’s queries at the beginning of the session or at trial junctures. This precondition facilitated comparisons of anticipatory or reflective comments and physical action. These comparisons provided insight into the type of information (e.g., sensorimotor, verbal) a subject might be accessing to guide behavior. Additionally,

110 N. Moses

at the beginning of each session, the investigator told subjects to feel free to talk about the task as they went along. Subjects, however, were nor instructed to “think out loud.” This was an effort to access subjects’ thoughts throughout their engagement with the task, while minimizing interference with their natural tendencies to speak or be silent while manipulating the rig (see Granott, 1993; Nisbett & Wilson, 1977). Patterns of talking and silence provided further clues to the type of information a subject might be accessing to guide behavior.

Each subject engaged in the task for up to 27 trials during three weekly half hour sessions. Subjects were urged not to practice at home between sessions. A trial began when a subject began manipulating the tractor at the begin position with the intention of parking the rig. A trial ended when the subject returned the rig to that area to begin again. This protocol was discontinued before the comple- tion of 27 trials when procedures and comments indicated that the subject reached the highest level of performance. All interactions were videotaped.

Overview of Data Analyses A Panasonic AG 6200 VHS video cassette player/recorder with variable speed control was used in the analysis of videotaped data. All data analyses were conducted by the investigator in collaboration with a Rutgers University graduate of a master’s degree in communication. Judgments were by consensus as recom- mended by Metz (1985) Shriberg, Kwiatkowski, and Hoffman (1984), and Wan- sart (1984).

Analyses of subjects’ behavior focused on four recurring task conditions: (1) within a trial juncture (when subjects responded verbally to questions posed by the investigator), (2) as subjects began to address a task demand with objects in hand, (3) as subjects responded to problems that arose as they were addressing a task demand with objects in hand, and (4) when a task demand shifted.

Two series of data analyses were performed to identify phases in the development of procedural knowledge. The identification of a developmental phase was based on evidence of a pattern in subjects’ cognizance of steering procedures and the rig’s movement relevant to a task demand, and in the organization of physical behavior. (The term cognizance denotes conscious knowledge, i.e., awareness upon reflection; Campbell & Bickhard, 1992.) A pattern in procedural knowledge or physical behavior could comprise one level of organization, or a de- limited range of variability in organization manifested across a series of trials.

The first series of analyses focused on physical behavior. In this series, physical behaviors that subjects executed under the second, third, and fourth task conditions were described, and the organization intrinsic to this behavior was analyzed. The aim of the second series was to ascertain subjects’ cognizance of steering procedures, the motion of the rig, and task demands, as well as subjects’ treatment of feedback. In the second series, selected aspects of subjects’ physical behavior were reassessed in light of environmental conditions that surrounded the behavior. Also, subjects’ verbal comments were evaluated.


In the description of methodology which follows, physical behaviors utilized to manipulate the tractor-trailer rig are referred to as procedural behavior. Such behavior is not necessarily accessible to consciousness (Karmiloff-Smith, 199 1; Piaget, 1978). Conscious knowledge about steering procedures, movement patterns, and task demands is referred to as procedural knowledge.

The First Series of Analyses

Describing andAnalyzing the Organization of Procedural BehaviorAccord- ing to Task Demand. First, the investigator and his colleague identified individual trials according to the criteria presented earlier. The task presented two primary demands: steering the trailer toward the goal parking position and responding to jackknifing. Consequently, on a trial-by-trial basis, the investigator and his colleague judged whether subjects were addressing the turn or jackknife task demand, described actions (i.e., procedural behavior) that subjects executed in response to task demands, and organized these descriptions according to the

task demand being addressed by the subject. Procedural behavior was classified on a trial-by-trial basis according to

scheme structure-that is, the organization intrinsic to the behavior. This analysis of the scheme structure of procedural behavior served as a basis for identify-

ing organizational characteristics of procedural knowledge. A taxonomy that described five types of scheme structure was created for this

analysis. These types of scheme structure were: (1) exploratory, (2) nonreversible single scheme, (3) single scheme plus exploratory reversal, (4) dual scheme, and (5) reversible scheme. Table 1 presents descriptions of these types of procedural behavior.

This taxonomy emerged as the investigator and his colleague made many passes through the videotaped data. Structural descriptions of behavior by Fischer (1980), Piaget (197 1, 1985), and Werner and Kaplan (1964) helped guide evaluations of the data. Behavioral categories, however, were based on subjects’ actions in context of the tractor-trailer task. This insured that subtle characteristics of procedural behavior relevant to the microgenesis of procedural knowledge would not be obscured by the use of less context-specific behavioral categories. One such characteristic that received special attention was the reversal of a previous steering movement through midline. (Reversing steering through midline will be referred to as a “steering reversal.” Midline refers to the steering position that points the tractor’s front wheels in a straight-forward position.) This focus on steering reversals was motivated by task characteristics, and is consistent with attention given to reversibility (i.e., an action that returns to its point of depar- ture) in describing organization intrinsic to action and representation by Piaget (1971; Piaget & Inhelder, 1969; Vin-Bang & Fluckiger, 1976).

Identifying Patterns and Transformations in the Organization of Procedural Behavior. The next step in these analyses involved identifying patterns in the

112 N. Moses

Table 1. Five Types of Scheme Structure Characteristic of Procedural Behavior and a Description of Behavior Manifesting Each ‘Qpe of Scheme Structure According to Task Demand

Type of Scheme Structure Turn

Task Demand

Jackknife

Exploratory

Nonreversible Single

Scheme

Nonreve~ibIe SingIe

Scheme + Explor-

atory Reversal

Dual Scheme

Reversible Scheme

Steer back and forth through mid- Steer back and forth through midline unsystematically. line unsystematically.

Steer tractor in the direction of the

goal parking position, end rrial

following failure.

Collide, pull forward, and then

with the steering positioned on

the same side of midline that

caused the problem, back up

again.

Steer in the direction opposite to

goal parking position, then

quickly abandon the reversal by

steering toward the goal parking

position.

Begin trial by steering in the di-

rection of the goal parking posi-

tion, then reverse steering

through midline when problem

arises.

Begin turn by steering in the di-

rection opposite to the goal

parking position.

Collide, pull forward, momen-

tarily back up with steering re-

versed through midline, then

quickly abandon the reversal-

repositioning steering to the

same side of midIine that

caused the probiem.

Collide, pull forward, then reverse

steering through midline and

back up.

Avoid collision by reversing steer-

ing through midline while back-

ing up.

organization of procedural behavior across trials and changes in patterns. Trial- by-trial sequences of procedural behavior were graphed according to scheme structure and task demand being addressed (see Appendix for examples). These graphs were examined by the investigator and his colleague. They identified consistent patterns in the scheme structure of procedural behavior across trial sequences, and noted trials in which a pattern changed. Trial sequences in which a pattern in the scheme structure of procedural behavior was identified were viewed as potentiai phases in the development of procedural knowledge.

The Second Series of Analyses The previous series of analyses focused on identifying patterns in the organization of procedural behavior over time. These analyses did not address the issue of subjects’ conscious knowledge. As such, a second series of analyses was performed to ascertain subjects’ cognizance of steering procedures, the motion of


the rig, and task demands (i.e., procedural knowledge). This second series of analyses was also aimed at understanding subjects’ treatment of feedback.

Because awareness can not be observed directly, verbal behavior was the primary evidence of conscious knowledge (Karrniloff-Smith, 1986a). Physical behavior executed in responding to problems, however, served as an additional source of information for making inferences about the lack of awareness of actions not utilized, the failure to recognize task demands, and subjects’ interpreta- tion of feedback conditions. In these analyses, subjects’ verbal descriptions (spontaneous and in response to the investigator’s “how” queries) and reactions to problems that arose as subjects were addressing a task demand were analyzed in light of surrounding feedback conditions. The termfeedback conditions refers to information that is generated by an individual’s own behavior.

Correspondences and inconsistencies between descriptive comments and the conditions they described were noted. With reference to a subject’s reactions to problematic feedback conditions, the investigator and his colleague noted what condition(s) seemed to evoke a particular reaction and proposed how subjects’ may have interpreted the condition(s). Finally, across-trial comparisons of subjects’ responses to recurring feedback conditions were made. This was a way of evaluating consistency and variation in procedural knowledge within and across trials.

Reliability. The graduate student independently judged 100 trials (the first 10 trials from 10 randomly selected subjects’ first sessions). She identified individual trials and task demands being addressed by the subject during each trial and also categorized procedural behavior on a trial-by-trial basis according to the taxonomy presented in Table 1. Furthermore, she independently identified developmental phase boundaries by evaluating the graphs of procedural behavior. Pro- portions of agreement between her judgments and the consensus judgments of the investigator were computed as measures of interrater reliability (trial boundaries = .98; task demands addressed = .96; type of procedural behavior = .93; developmental phase boundaries = .85).

RESULTS

Three phases were identified in the development of procedural knowledge concerning steering procedures and the motion of the rig. These phases are reflected in: (1) comments and other actions indicative of conscious knowledge, (2) procedural behavior, and (3) subjects’ treatment of feedback information. Further- more, a transformation was observed in subjects’ knowledge about task demands.

A great deal of information about subjects’ behavior-much of it descriptive -is relevant to conclusions that have been drawn. These results have been organized as follows. The three developmental phases are described with reference to subjects’ knowledge of steering procedures and the rig’s movement, procedural

114 N. Moses

behavior, treatment of feedback, and consistency of behavior as conditions changed within individual trials. Following these descriptions, proportional data are presented concerning types of procedural behavior that constituted developmental phases and developmental characteristics of individual subjects and male and female subject groups. Next, the shift in subjects’ knowledge about task demands is depicted, and results of an analysis of the temporal synchrony of development in context of the two task demands are reported.

Phases in the Development of Knowledge of Steering Procedures and Movement Patterns

Phase 1. During the first developmental phase, subjects appeared to be cognizant of one steering procedure when responding to each of the task demands. To turn the rig toward the goal parking position, the procedure was to steer toward the goal parking position; in response to jackknifing, the procedure was to pull forward and back up again, steering in the direction that lead to jackknifing. Subjects described these procedures verbally (at trial junctures), utilized these procedures when systematically approaching each task demand, and reiter- ated these procedures when responding to problems. Figure 3 illustrates this error pattern in context of the two task demands.

This first phase was also characterized by the envisionment of undifferentiated movement of the rig (toward the direction of steering). In commenting upon turning, subjects generally linked the trailer’s trajectory directly to the tractor’s, and expected the rig to back-up from its starting position to its goal location in one smooth move. Some subjects expressed the wish that the tractor and trailer be rigidly connected (as opposed to pivoting). Subject M-C (Trial 5) commented that if the tractor and trailer were rigidly attached you could do it “like a bus.” Subject F-B actually tried taping the tractor and trailer together before her first trial.

The behavior previously described appears to reflect holistic, nonreversible organization. In addition to this behavior, subjects exhibited exploratory procedural behavior during Phase 1. In such behavior, subjects unsystematically steered back and forth through midline. After executing exploratory behavior, subjects quickly returned to their systematic wrong-way steering procedure, either within a trial or in the next trial. There was a lack of correspondence between subjects’ execution of exploratory reversals and their efforts to describe their behavior at a subsequent trial juncture: Subjects omitted references to the reversals.

These results reveal two degrees of organization within behavior expressed during Phase 1: (1) more systematic organization, (holistic, nonreversible), manifested in verbal constructs and single scheme, nonreversible procedural behavior; and (2) less systematic organization, seen in exploratory procedural behavior. Subjects did not appear to take cognizance of feedback from reversals


Figure 3. Phase 1 errors in turning and compensating for jackknifing.

executed in context of the exploratory behavior. Feedback from the rig’s movement following the execution of exploratory reversals appeared to evoke the reit- eration of a wrong-way steering procedure.

Phase 2. At Phase 2, subjects verbally entertained two possible steering procedures when queried during trial junctures: the Phase 1 procedure or reverse the direction of steering. All subjects expressed uncertainty about which procedure to utilize and when to utilize it. Some subjects made comments in context of the turning task demand which indicated that they were rethinking their holistic view of the rig’s movement pattern. For example, subject F-G stated (commenting on the turning task demand before the first trial of the second session): “I realized as you move the tractor and trailer back . you have to start cutting the wheels one way and then you have to change it the other way. . . . I was starting to see the trailer really does not move the same way as the back wheels of the

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tractor and I have to examine-look at the back wheels here and start paying attention to the wheels there.” Subjects’ verbal references to possible steering procedures and the rig’s movement suggest that these aspects of procedural knowledge were undergoing differentiation during Phase 2.

In contrast to subjects’ stated uncertainty about which way to steer in approaching a task demand, subjects almost invariably addressed task demands by first steering the wrong way. Then, after running into a problem that resulted from the use of an inadequate procedure, they steered the other way. This inflex- ible procedural sequence did not correspond to subjects’ verbalized uncertainty about which procedure to utilize.

Two additional noncorrespondences concerning steering reversals were identified within a sequence comprising a trial, trial juncture, and subsequent trial. One was discemable when subjects were asked to describe their behavior after they had reversed steering direction. Subjects often reported steering in the non- reversed direction (or were unable to recall what they had just done). For example, subject M-C said that he had avoided jackknifing “. . by using a more gradual [turn] motion. At least that’s how I think 1 did it.” He had actually pulled forward and reversed steering through midline. Subject F-C, after actually reversing the wheels sharply through midline during the previous trial, explained how to avoid jackknifing: “Pull forward a bit and turn the wheels the other way a tiny bit.” Similarly, subject F-G suggested to “start turning the steering wheel this way” (reverse direction of steering). Then, with wheels at midline, “stop.” A second noncorrespondence was observable when invariably, after reversing steering direction in response to a problem, subjects initiated the next trial by again steering in the wrong direction.

These findings indicate that during Phase 2, subjects did not make verbal references at trial junctures to feedback from steering reversals that they had physically demonstrated. Furthermore, subjects did not use kcdwledge about steering reversals verbalized at trial junctures to guide their procedural behavior. Instead, feedback from the rig’s wrong-way movement appeared to serve as a necessary signal for executing a steering reversal when subjects were physically engaged with the task.

Phase 3. At Phase 3, subjects described appropriate steering procedures and the rig’s oppositional movement pattern. These verbal descriptions corresponded with the expression of reversible procedural behavior; that is, steering reversals in anticipation of the rig’s oppositional movement pattern and ongoing adjust- ments in steering in response to the rig’s ongoing shifts in direction. These findings suggest that the organization of procedural knowledge at the third phase of development was reversible and differentiated. They also indicate that subjects were cognizant of feedback from steering reversals and the rig’s oppositional movement pattern, and made verbal and physical references to this information across all task conditions except shifts in task demands (Le., when queried, when approaching a task demand, when reacting to problems).


Table 2. Proportion and Frequency of Expression of ‘Qpes of Procedural Behavior According to Developmental Phase

Type of Procedural Behavior

Nonreversible Single Scheme

Nonreversible + Exploratory Dual Reversible Total No. Phase Exploratory Single Scheme Reversal Scheme Scheme of Tokens

I .23(42) .24(45) .37(68) .12(22) .05(9) 186 2 .01(l) .00(O) .01(2) .76( 143) .22(41) I87 3 .00(O) .01(l) .00(O) .04(4) .95(96) 101

The Distribution of Procedural Behavior Across Phases. The proportion of

trials during each developmental phase in which subjects employed five types of procedural behavior in manipulating the rig is presented in Table 2. These data, which are consonant with the earlier descriptions of the developmental phases, indicate the following: At Phase 1, subjects executed nonreversible single scheme procedural behavior, nonreversible single scheme plus exploratory reversal procedural behavior, and exploratory procedural behavior. At Phase 2, subjects expressed dual scheme procedural behavior almost exclusively, and at Phase 3, reversible scheme. (Descriptions of these types of procedural behavior are presented in Table 1.)

Descriptive Statistics on Developmental Transitions and the Length of De- velopmental Phases. Table 3 presents developmental transitions exhibited by subjects and the number and proportion of subjects who exhibited each transition. These data indicate that across subjects, development was unidirectional, proceeding from Phase 1 to Phase 3. However, not all subjects manifested all levels of functioning, and consequently, not all subjects manifested all phase transitions. In turning toward the goal-parking position, 6 subjects (.43) manifested all levels of functioning and all phase transitions. Three (.21) transitioned from Phase 1 to Phase 2, 3 (.21) from Phase 2 to Phase 3, and 1 (.07) from Phase I to Phase 3. One subject performed solely at Phase 3.

In response to jackknifing, 4 subjects (.29) manifested all levels of functioning, 4 (.29) manifested a transition from Phase 1 to Phase 2, and 2 (. 14) moved from Phase 1 to Phase 3. Three subjects (.21) exhibited a single level of functioning: 1 Phase 1, 1 Phase 2, and 1 Phase 3. It is notable that the one male subject who reported having driven a car with a boat trailer attached was unable to resolve the jackknife task demand.

Table 4 presents the mean, standard deviation, and range for the number of trials subjects remained within each of the three developmental phases.

Variability in Performance and Gender. The data in Tables 3 and 4 indicate variability in performance among subjects. One possible source of individual

118 N. Moses

Table 3. Developmental Transitions Exhibited by Subjects and the Number of Subjects Exhibiting Each Transition Organized According to Task Demand

Transition Task Demand

Number and Proportion of Subjects

Manifesting the Transition

Phases l-3 Turn

Jackknife

Phases l-2 Turn

Jackknife

Phases 2-3

Turn Jackknife

.43 (6)

.29 (4)

.21 (3)

.29 (4)

.21 (3)

Phases l-3 Turn

Jackknife

.07 (1)

.14 (2)

Note. In addition to the performance characteristics of subjects represented above, one subject performed exclusively at Phase 1 in addressing the jackknife task demand, one performed exclusively at Phase 2 in addressing the jackknife task demand, two performed exclusively at Phase 3 in addressing the turning task demand, and one performed exclusively at Phase 3 in addressing the jackknife demand.

differences is gender. There is literature that suggests that men perform better than women on tasks that involve spatial cognition (Connor & Serbin, 1985). Furthermore, the theme of the task utilized in the present study-manipulating a tractor-trailer rig-may be of greater interest to men than women. To assess the possible relation between gender and performance, two comparisons were made

Table 4. Mean, Standard Deviation, and Range for Number of Trials Subjects Remained Within Each of the Three Develonmental Phases

Torn I 2 3

Jackknife I 2

3

Mean

4.79

7.00 15.00

8.42 7.00

8.92

Standard Deviation

I .33

1.87 2.51

2.17 2.08

2.59

Range

O-18

O-23 O-27

O-27 o-22

O-27


Table 5. Proportion and Number of Subjects Reaching Phase 3 According to Gender and Task Demand, and Results of a One-Way ANOVA Derived From Comparing the Developmental Level Achieved by Men and Women

Task Demand

Tarn Jackknife

Men

Women

Result of

One-Way ANOVA

1 .oo (7) .58 (4)

.58 (4) .58 (4)

F(1, 12) = 0.90 (n.s.)

Note. To compute the ANOVA, subjects were assigned scores according to the following system: 0 = did not reach Phase 3 in context of either task demand; 1 = reached Phase 3 in context of one task demand; 2 = reached Phase 3 in context of both task demands. Then a mean score was computed for men and women, and an ANOVA was conducted on variation around that mean.

on performance: (1) a one-way analysis of variance (ANOVA) comparing the level of performance achieved by each of the groups in context of the two task demands, and (2) a one-way ANOVA comparing the number of trials that subjects in each group took to reach Phase 3 in addressing each task demand. Results of these comparisons, reported in Tables 5 and 6, revealed no significant difference in level of functioning achieved by the two subject groups. In context of the

Table 6. A Comparison of the Mean Number of Trials During Which Men and Women Performed Below Phase 3

Men

Women

Result of One- Way ANOVA

Task Demands

Turn Jackknife

7.14 15.28

16.86 20.57

F(1, 12) = 4.81* F(l, 12) = 1.04

Total

Turn Jackknife

50 82

122 154

*p < .05.

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turning task demand, however, women as a group took significantly longer than men to achieve Phase 3 functioning, F (I, 12) = 4.81, p < .05.

Knowledge of Task Demands In the course of the analyses described earlier, an unanticipated trend became apparent in the behavior of a number of subjects. These subjects exhibited reversible actions in steering the rig toward the goal parking position. When the rig subsequently jackknifed, however, they responded by executing nonreversible actions. Recognition of these different levels of organization in subjects’ behavior during individual trials provided direction for a planned evaluation of subjects’ cognizance of task demands. These observations also prompted an additional assessment of the temporal synchrony of development in context of each task demand.

Cognizance of Task Demands. The evaluation of knowledge of task demands focused on subjects’ efforts to steer the rig toward the goal parking position, their responses to the trailer’s subsequent jackknifing, and their follow-up attempts to turn the rig toward the goal parking position during the next trial. This evaluation revealed a transformation in knowledge of task demands in all but one subject. Subjects initially treated the jackknifing problem as a turning problem. When the rig jackknifed, they either: (a) pulled forward and then backed up again without varying steering from the turn position (thus executing another turn); (b) gave up, began another trial, and turned less sharply (thus executing a modified turn); or (c) gave up, began a new trial, and reverted back to an incorrect turning procedure (thus blaming a successful turn procedure for a nonturn problem). Subsequently, subjects “upgraded” jackknifing from a problem caused by incorrect turning to a separate task demand. They maintained correct turning procedures while devising a second reversal aimed at preventing jackknifing. This transition occurred when subjects were at Phase 2 or Phase 3 in responding to the turning task demand, but before subjects achieved Phase 3 knowledge about jackknifing.

An Assessment of the Temporal Synchrony of Development in Context of the Two Task Demands. For each task demand, and for each trial that subjects were engaged with the task, the proportion of subjects performing at each of the three developmental phases was computed. These proportions were then graphed according to developmental phase and subject group. These graphs, which compare across-trial shifts in the proportion of subjects performing at each developmental phase in addressing the turning and jackknifing task demands, are presented in Figure 4.

.These graphs illustrate a parallel but asynchronous pattern of development for procedural knowledge relevant to the turning and jackknifing task demands. Pro- cedural knowledge relevant to each task demand exhibited the same developmen-

Procedural Knowledge in Adults

Figure 4. Graphs comparing across-trial shifts in the proportion of subjects performing at each of three developmental levels in addressing the turning and jackknifing task demands. (Note that the proportions were computed by dividing the number of subjects functioning at the developmental phase during a particular trial by the total number of subjects who were judged as functioning at the developmental phase.)

tat transformations. However, there was a lag in phase transitions in the development of procedural knowledge relevant to the jackknife task demand as compared to the turn task demand.

DISCUSSION

A microanalysis of the behavior of 14 adults engaged in a tractor-trailer task revealed three phases in the development of knowledge of steering procedures

122 N. Moses

and the rig’s movement patterns. Subjects’ verbal comments and procedural behavior during the first phase of development reflected two levels of organization: nonreversible single scheme (manifested in verbal comments and procedural behavior) and a less systematic organization (reflected in exploratory procedural behavior). Subjects appeared to be unaware of feedback from steering reversals that constituted exploratory behavior.

At the second phase of development, procedural knowledge and procedural behavior appeared to be undergoing differentiation. Verbal references to procedures and procedural behavior exhibited dual scheme organization. Within trials, access to information about steering reversals seemed to fluctuate as task conditions relevant to a task demand shifted. When physically addressing a task demand, subjects did not express steering reversals until they observed feedback from the rig’s wrong-way movement. When asked to anticipate procedures during trial junctures, subjects referred to steering reversals as a possible approach to the task demand. When asked to describe their procedural behavior after executing a steering reversal, they omitted references to reversals.

At the third phase of development, procedural knowledge expressed verbally and procedural behavior corresponded. Subjects referenced and executed reversible procedures and accurately described the rig’s oppositional movement pattern across changes in task conditions.

In addition to these phase-specific developmental changes, a shift was observed in subjects’ knowledge of task demands. Initially, subjects seemed to be aware only of the turning task demand; jackknifing was treated as a consequence of an improper turning procedure. Subsequently, subjects recognized jackknifing as a separate task demand. Related to this shift, subjects as a group simultaneously manifested different levels of functioning in context of each task demand. They exhibited phase transitions first in context of the turning task demand and then, with some delay, in context of jackknifing.

These findings support an epigenetic view of procedural knowledge in adults. Although a small number of adults were observed in a narrow context, the changes observed in their behavior are suggestive of processes involved in the development of procedural knowledge in adults engaged in novel action-oriented tasks. These processes involve: (a) the application of multiple modalities to the representation of procedures; (b) a sequence of organizational parameters which constrains representation, impacts upon feedback regulation, and thereby defines developmental phases; and (c) the centrality of knowledge of task demands in developmental transitions. These processes are later discussed, followed by a consideration of developmental differences which were observed among individual subjects, and between men and women.

Multiple Modalities In line with suggestions made by T.R. Bide11 (personal communication, June 3, 1991) and Karmiloff-Smith (1986a, 1991), adults appear to apply multiple mo-


dalities to the representation of information relevant to the problem at hand. In responding to the tractor-trailer task, adults in the present study generated sensorimotor procedures, verbal theories, gestural representations of procedures, and so forth. The accessibility of feedback information to representation across modalities and across task conditions appeared to change with development. This shift in accessibility was reflected, primarily, in the abilities to verbally anticipate or recall physical procedures, and enact procedures described verbally. Acces- sibility of feedback to representation seems to be a function of organizational parameters underlying procedural knowledge and procedural behavior.

Organizational Parameters Results from the present study indicate that during any one phase of development, all procedural constructs related to a task demand (i.e., acts comprising procedural behavior and envisioned in procedural knowledge) may be constrained within a relatively narrow organizational parameter. This constraint appears to apply regardless of the modality through which the construct is generated or represented. In context of the tractor-trailer task, which had strong directional and spatial elements, procedural behavior and procedural knowledge were subject to three organizational parameters: the first ranging from non- systematic (i.e., preorganized) to holistic/nondifferentiated and nonreversible organization, the second being dual scheme organization; and the third differentiated and reversible organization.

Accessibility of feedback from procedural behavior to representation across modalities and across all task conditions, except shifts in task demands, appeared to be constrained by these three organizational parameters. During Phase 1, feedback from procedural behavior that manifested holistic, nonreversible organization was accessible to consciousness and to across-modality representation. Accessibility remained stable as task conditions fluctuated. Feedback from the less systematic exploratory behavior that conflicted with parameters of the more systematic organization (i.e., feedback from exploratory reversals) appeared to be resistant to cognizance and representation across modalities. However, the seeds of reorganization seemed to be contained in this feedback information. During Phase 2, information related to newly differentiated and reversible aspects of behavior was accessible to verbal representation when individuals were not physically engaged in the task, and to physical representation when specific feedback conditions signaled a failed goal achievement. Such information did not appear to be accessible to representation when approaching a task demand. At Phase 3, information from differentiated and reversible aspects of behavior appeared to be accessible to representation in all behavioral modalities and to cognizance under all task conditions studied, except changes in task demand.

The fluctuations in the accessibility of feedback information to representation suggest that the organization underlying procedural knowledge is sensitive, within limits, to shifts in conditions within a task. Recall that there were four major

124 N. Moses

conditions under which subjects in the present study were called upon to express procedural knowledge during individual trials: (1) trial junctures, when subjects were asked to comment on the task without manipulating objects; (2) the onset of task demands, when subjects had to execute a procedure with objects in hand; (3) problematic situations, signaled by environmental feedback; and (4) shifts in task demands that subjects had to address.

Under the first, second, and third task conditions, fluctuations in organization remained within parameters that defined the phase. These oscillations in organization stabilized with development. Throughout the course of this study, however, there were striking fluctuations in organization when the task demand that the subject was addressing changed (the fourth task condition). Often, fluctuations in behavioral organization under this task condition went beyond phase-defining parameters. The issue of task demands is later discussed at greater length.

Knowledge of Task Demands Task demands seemed to serve several crucial roles in the development of procedural knowledge. Knowledge of task demands appeared to serve as a point of reference for coordinating procedures, and for evaluating problems and procedures (consistent with proposals made by Blanchet, 1983; Case, 1985; Galam- bos, 1986; Wansart, 1990). These organizing functions were manifested in subjects’ tendency not to generalize developmental achievements across task demands. The majority of subjects learned to systematically use reversals first in context of the turning task demand. As they did, they continued to manifest nonreversible behavior in context of jackknifing-simultaneously functioning at different levels in context of different task demands. One of these subjects remained at Phase 1 in context of jackknifing for 27 trials, although he had quickly achieved Phase 3 success in context of turning. (This developmental pattern, and possible exceptions, are discussed at greater length later in the section on differences among subjects).

Subjects’ knowledge of task demands appeared to interact with their phase- specific use of feedback information to provoke re-representations and reorgani- zations of all aspects of procedural knowledge. The interaction of these variables seemed to create problems that stimulated the differentiation of knowledge about task demands and increased the probability that subjects would take cognizance of information from steering reversals and the rig’s oppositional movement. Let us consider how this developmental mechanism may have proceeded.

Recall that subjects tended to overlook information from steering reversals and oppositional movement during Phase 1 and 2. Subjects also erroneously treated jackknifing as a turning problem. The outcome of these tendencies stimulated, in context of turning, the expression of unsystematic exploratory and dual scheme behavior (which comprised steering reversals and lead to much oppositional movement by the rig). These tendencies also lead to multiple encounters with jackknifing. Multiple encounters with jackknifing appeared to stimulate rec-


ognition of jackknifing as a distinct task demand. The discovery of a new task demand may have provoked a reexamination of reversals and oppositional movement. This reexamination may have led to greater cross-modality access to and cognizance of information about procedural reversals, and the differentiation of knowledge about the rig’s movement characteristics.

Developmental Differences Among Subjects It has been emphasized several times in the course of this study that development proceeded in a parallel but temporally asymmetric manner in context of the two task demands-turning and jackknifing. A careful inspection of the behavior of individual subjects suggests that this developmental profile was clearly exhibited by 9 (.64) subjects. These subjects manifested developmental transformations first in context of the turning task demand and then in context of jackknifing- simultaneously functioning at different levels in context of different task demands .

A second, smaller group of 4 (.21) subjects, may have generalized knowledge across task demands. Three of these subjects, in context of the jackknifing task demand, manifested a single level of procedural knowledge (Phase 2 or Phase 3). They did not appear to try to systematically address the jackknifing problem until first achieving Phase 2 (successful use of reversals) in response to turning. A fourth subject, who started out at Phase 3 in context of turning, skipped Phase 2 in response to jackknifing. In these subjects, the expression of reversals in context of turning seemed to inform procedural behavior in context of jackknifing.

The behavior of one subject was somewhat puzzling. This subject skipped Phase 2 first in context of the turning task demand, and then with some delay in context of jackknifing. This result raises the possibility that the second phase of development can be skipped altogether. Another explanation is that data analysis techniques employed in the present study were not sensitive enough to determine Phase 2 levels of functioning in this subject. This subject seemed to exemplify the first developmental profile previously discussed-utilizing feedback generated in context of one task demand to resolve that task demand, without gener- alizing behavioral achievements across task demands. This was suggested by the subject’s achievement of Phase 3 in context of the turning task demand while still manifesting Phase I in addressing the jackknifing task demand. Exploratory steering reversals which were expressed during Phase 1 in context of each task demand could have been foundational for achieving Phase 3 functioning (the systematic use of reversals) in each task demand context.

In light of controversy surrounding the issue of spatial cognition in women as compared to men (e.g., Chipman, Brush, & Wilson, 1985; McGillicuddy-DeLisi et al., 1978), it is notable that no significant difference was found in comparing the level of development reached by men and women. There was a significant difference in rate of development in favor of men only in context of the turning task demand-the first task demand that had to be at least partially resolved for

126 N. Moses

the jackknife task demand to become a problem. These findings are suggestive of a direction for future research.

In the present study, there was an absence of the time constraints that are traditionally placed on subjects solving spatial problems (e.g., Connor & Serbin, 1985; McGillicuddy-Delisi et al., 1978). It is possible that, given adequate time and the freedom to revise problematic behavior, women would compare favora- bly to men in learning to solve problems that involve spatial cognition. Addition- al research conducted along such lines could be helpful in clarifying this issue.

CONCLUSIONS

It is possible to conclude that in the course of problem solving, procedural knowledge in adults is subject to a complex and dynamic developmental process which diverges in several ways from common sense expectations and traditional stage theory. One component of this process is the application of multiple modalities to the representation of a problem solution. This yields procedural knowledge (conscious knowledge of task demands, actions that will be utilized to achieve task demands, characteristics of objects that will be manipulated) and procedural behavior (i.e., actions actually utilized in manipulating objects to achieve recognized task demands and resolve problems).

A second component is the holistic nature of organization that initially may embody both procedural knowledge and procedural behavior. It is characteristic of holistic organization that critical task demands are not recognized, physical action is not subject to verbal regulation, and important feedback information from physical action is overlooked.

A third aspect of development is the differentiation and reorganization of procedural knowledge and procedural behavior. Reorganization proceeds, initially,

in context of the task demand being addressed consciously, and draws on feedback from procedural behavior. One byproduct of task-demand specific reorganization is across-modality access to information relevant to resolving a task demand. A second byproduct is the appearance of new problems, which stimu- lates the discovery of new task demands. Such discoveries lead to further acts of holistic representation, differentiation, and reorganization with reference to the newly discovered task demand. They also lead to further developments in and stabilization of procedural knowledge relevant to the first known task demand. This process may continue until all relevant task demands and procedures inte- gral to their resolution are known. The end product of this process, with reference to the original task (e.g., parking the tractor-trailer rig), is the ability to regulate problem-solving behavior knowing what feedback to expect following an action, and how to interpret that feedback with reference to the resolution of task demands. One can envision development continuing beyond such practical ends. Individuals can pose for themselves new, more complex and abstract task demands. An example, perhaps, is my creation of a tractor-trailer task to explore


processes underlying the development of procedural knowledge in adults. I drove

tractors as a child on a farm. Three factors appeared to provoke developments in procedural knowledge in

the present study. The first involved problems that arose as subjects were leam- ing to resolve a recognized task demand. Problems stimulated spontaneous efforts to find soiutions and the discovery of additional task demands. A second was the interaction between the investigator and subjects. The investigator required subjects to try again when problem solutions failed, and reflect upon problem solutions. The third appeared to be subjects’ natural tendency to re- represent and reorganize problem solutions utilizing multiple representational

modalities, as Karmiloff-Smith (1991) proposed. Several aspects of development observed in the present study bear upon an

issue raised in many of the problem-solving studies cited throughout this article-how learning to solve one problem might relate to the discovery of a solution to another (e.g., Case, 1985; Fischer, 1980; Greeno, 1983; Metz, 1985). Two interfering factors may be the tendency of individuals to approach the identification and resolution of task demands from a holistic perspective, and the tendency to relate specific procedures to specific task demands. The ability to recollect and apply known procedures in novel contexts may require an obvious similarity between a present and previously encountered task demand (Fischer, 1980). Otherwise, given a complex novel problem, adults seem to identify one obvious task demand and generate holistic procedures. In such cases, the achievement of knowledge of an adequate problem solution is a consequence of the developmental process which ensues. Two additional factors that may influ- ence the utility of prior experience given a novel problem are the manner in which problem solutions have been represented (e.g., modularly vs. across- modalities; Karmiloff-Smith, 1986b), and the degree of awareness an individual may have of particular actions.

It also is possible that the relevance of prior problem-solving experiences to the derivation of solutions to novel problems may be affected by causal knowledge (e.g., in the present task, knowing that resistance from an object would have an effect on the trajectory of a force exerted on that object). In the present study, subjects referred to causality only to explain why their procedures did not seem to work. They offered explanations such as, “The tractor and trailer are not really connected.” The issue of how causal knowledge relates, developmentally, to procedural knowledge deserves investigation, and I address this in a follow-up study.

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