THE EFFECTS OF PSYCEOPEIYSICU MTCEUNG OH TEfB TRBNSPER OF TRAINING BETWEEN ALTERNATIVE MOTION SIMULATORS

John M . Flach Aviat ion Research Laboratory

Un ive r s i t y of I l l i n o i s a t Urbana-Champaign

Grant R . McMillan and Rik Warren A i r Force Aerospace Medical Research Laboratory

Wright-Patterson A i r Force Base

Melodie K . S n e l l Systems Research Labora to r i e s , Inc .

Dayton, Ohio

ABSTRACT ,

Psychophysical matching t.echniques were employed t o equate t h e s u b j e o t i v e e4par ienoe o f motion i n two motion s imu la t ion deviqes- t he RATS, a whole-body m o t i o n e n v i r o n m e n t and t h e ALCOOS, whioh p r e s e n t e d mot ion eues t h rough a moving seat-pan, The psyohophysioal. matahing technique was designated SIGMA, f o r S u b j e o t i v e I n t e r a o t i v e Gain Measurement Analysis. Use of t h e motion d r i v e a lgo r i thm, d e r i v e d us ing S I G M A , r e s u l t e d i n e q u i v a l e n t r o l l - a x i s t r a a k i n g pe r fo rmance be tween t h e two simulators. However, t r a i n i n g s u b j e c t s i n t h e ALCOGS u s i n g t h i s m o t i o n d r i v e a l g o r i t h m d i d n o t r e s u l t i n b e t t e r t r a n s f e r between s i m u l a t o r s than t r a i n i n g wi th no motion cues.

INTRODUCTION

The Advanced LOW*-cost G-Cuing System (ALCOGS) was developed t o f u l f i l l t he need f o r a " h i g h l y r e s p o n s i v e and f l e x i b l e r e s e a r c h G-cuing sys t em f o r t a c t i c a l a i r o r a f t s i m u l a t i o n w (K le inwaks , 1980). T h i s sys t em i n o l u d e s h y d r a u l i c a l l y- a c t u a t e d seat- pan, backres t , and s e a t b e 1 t elements mounted i n an a i r c r a f t seat frame. The Air Force Aerospaoe Medical Research Laboratory has r e c e n t l y been i n v e s t i g a t i n g t h e f e a s i b i l i t y of u s i n g t h e ALCOGS t o p r o v i d e motion o n s e t in format ion i n s imu la t ed f l i g h t environments (McMillan, Levison, h Martin, 1984; Levison, McMillan, & Martin, 1984; Mar t in , '1985). The r e s u l t s from t h e s e i n v e s t i g a t i o n s have been mixed. On the one hand, performanoe i n a r o l l - a x i s t r a o k i n g t a s k showed s i g n i f i c a n t improvement when r o t a t i o n a l i n f o r m a t i o n was p r o v i d e d u s i n g t h e o n e- p i e a e s e a t - p a n o f t h e ALCOGS. T h i s sugges t s t h a t u s e f u l in format ion is provided by the dynamic seat-pan. Yet, on t h e o t h e r hand , u s e o f t h e dynamic s e a t- p a n d i d n o t improve t r a n s f e r t o a similar r o l l - a x i s t r a c k i n g t a s k performed i n a whole-body motion s imu la t ion p r o v i d e d by t h e R o l l - A x i s T r a c k i n g S i m u l a t o r (RATS). Tha t is , s u b j e o t s t r a i n e d w i t h m o t i o n c u e s p r o v i d e d t h r o u g h t h e s e a t- p a n of t h e ALCOGS d i d no b e t t e r when t r a n s f e r r e d t o a whole- body mot ion e n v i r o n m e n t t h a n s u b j e a t s t r a i n e d i n a s t a t i c (no m o t i o n ) env i ronmen t . The . o b j e c t i v e of t h e p r e s e n t i n v e s t i g a t i o n was t o improve t h e t r a n s f e r of t r a i n i n g between the moving sea t - pan of t h e ALCOGS and t h e whole-body motion' of t he RATS through manipulat ion o f . t h e a l g o r i t h m used t o d r i v e t h e seat-pan of the ALCOGS.

This i n v e s t i g a t i o n began w i t h t h e h y p o t h e s i s t h a t p o s i t i v e t r a n s f e r between t h e ALCOGS and t h e RATS could be improved by inc reas ing t h e s u b j e c t i v e e q u i v a l e n c e between t h e motion experience provided by t h e two d i f f e r e n t motion

d e v i c e s . G i v e n t h i s h y p o t h e s i s , t h e p r o b l e m became o n e o f d e v e l o p i n g a m e t h o d o l o g y f o r c o m p a r i n g t h e s e n s a t i o n s i n t h e two s i m u l a t o r s w h i c h w o u l d p r o v i d e i n s i g h t f o r c h o o s i n g a n ALCOGS d r i v e a l g o r i t h m . T h i s p r o b l e m i s s c h e m a t i c a l l y d e p i c t e d i n F i g u r e 1.

F i g u r e 1.

I Perceived

H ~ ~ ~ G S . MOI ton

The proble m of equaring t h e e x p e r i e n c e of motio n for t h e ALCOGS and t h e RATS.

SIGMA

The me thodo logy choseri f o r compar ing t h e q u a l i t y o f mot ion e x p e r i e n c e d i n t h e two a l t e r n a t i v e m o t i o n d e v i c e s was d e s i g n a t e d SIGMA, f o r S u b j e c t i v e I n t e r a c t i v e G a i n M e a s u r e m e n t A n a l y s i s . S I G M A e m p l o y e d a c r o s s m o d a l i t y m a t c h i n g p r o c e d u r e i n w h i c h s u b j e c t s a d j u s t e d t h e a n g u l a r a m p l i t u d e o f t h e mot ion c u i n g d e v i c e (RATS or ALCOGS s e a t - p a n ) t o match t h e a n g u l a r a m p l i t u d e o f a m o v i n g v i s u a l r e f e r e n c e . The f o u n d a t i o n f o r t h i s m e t h o d r e s t s w i t h S t e v e n s f ( 1 9 7 5 ) c l a s s i c i n v e s t i g a t i o n s i n t o p s y c h o p h y s i c s a n d more s p e c l f i o a l l y w i t h h i s s t u d i e s o f c r o s s m o d a l i t y matching . The u n i q u e f e a t u r e of S I G M A was t h a t mo t ion o f b o t h t h e v i s u a l r e f e r e n c e and t h e s i m u l a t o r were c o n s t r a i n e d t o b e s i n u s o i d a l i n fo rm. F u r t h e r , f r e q u e n c y o f t h e m o t i o n was i n c l u d e d a s a n i n d e p e n d e n t v a r i a b l e . T h a t i s , s u b j e c t s w e r e a s k e d t o m a t c h a n g u l a r a m p l i t u d e s a t s i x d i f f e r e n t f r e q u e n c i e s .

The l o g i c o f SIGMA i s i l l u s t r a t e d i n t h e e q u a t i o n s below. E q u a t i o n s 1 and 2 r e p r e s e n t t h e c r o s s m o d a l i t y m a t c h i n g p r o c e d u r e s i n w h i c h s e n s e d v i 5 u a l - motion ( dJ VISUAL) was c ~ m p a r e d t o s e n s e d mot ion i n t h e two s i m u l a t o r s dJ RATS a n d ) as a f u n c t i o n o f f r e q u e n c y ( w ) . G I a n d G 2 r e p r e s e n t t h e ga n adjustkkrft?z%o t h e a n g u l a r a m p l i t u d e of t h e r e f e r e n c e s i g n a l (0. These g a i n a d j u s t m e n t s were t h e d e p e n d e n t measures , S i n c e t h e v i s u a l r e f e r e n c e s i g n a l s i n t h e two c r o s s m o d a l i t y m a t c h i n g t a s k s r e p r e s e r l t e d by E q u a t i o n s 1 and 2 were i d e n t i c a l , t h e s e n s e d m o t i o n i n t h e two s i m u l a t o r s c o u l d be c o m p a r e d as i n E q u a t i o n 3. E q u a t i o n 3 compares t h e two s i m u l a t o r s -in t e r m s o f t h e g a i n s (G and Gp) a;;d t h e p h y s i c a l r e f e r e n c e s and ( A L ~ O G S ) . F i n a l l y , E q u a t i o n 1 d e m o n s t r a t e s how t h e g a i n r a t i o s ( O ~ ? U ~ / G , ( W ) ) c a n be t r e a t e d a s a q u a s i - d e s c r i b i n g f u n c t i o n f o r e q u a t i n g t h e two s i m u l a t o r s . T h i s d e s c r i b i n g f u n c t i o n c a n t h e n be used t o se lec t t h e l i n e a r d i f f e r e n t i a l e q u a t i o n t o be used as t h e d r i v e a l g o r i t h m f o r t h e A L C O G S s e a t - p a n . I t was h o p e d t h a t t h i s d r i v e a l g o r i t h m would r e s u l t i n s u b j e c t i v e e q u i v a l e n c e between t h e s e n s e o f mot ion i n t h e two s i m u l a t o r s .

Procedure

The v i s u i l r e f e r e n c e s i g n a l used f o r t h e S I G M A p rocedure c o n s i s t e d of a h o r i z o n t a l l i n e p i v o t i n g a b o u t Its c e n t e r p o i n t a t a p a r t i c u l a r f r equency and a n g u l a r a m p l i t u d e . T h i s r e f e r e n c e was d i s p l a y e d u s i n g a 9" d i a g o n a l T V m o n i t o r w h i c h was mounted a t s u b j e c t s t e y e l e v e l i n b o t h t h e RATS a n d t h e ALCOGS. S u b j e c t s w e r e a s k e d t o a d j u s t t h e a n g u l a r a m p l i t u d e o f t h e m o t i o n d e v i c e (RATS o r ALCOGS) s o t h a t i t s a n g u l a r motion matched t h a t of t h e v i s u a l r e f e r e n c e . Adjus tments were made u s i n g a f o r c e s t i c k mounted t o t h e r i g h t o f a s u b j e c t ' s s e a t . T h i s p rocedure i s i l l u s t r a t e d i n F i g u r e 2. It is impor tan t t o n o t e t h a t t h e v i s u a l r e f e r e n c e and t h e motion c u i n g d e v i c e were d r i v e n by a s i n g l e s i n e wave. The a n g u l a r a m p l i t u d e o f t h e v i s u a l r e f e r e n c e was f ixed . The a n g u l a r a m p l i t u d e o f t h e m o t i o n d e v i c e was s e t t o z e r o t o b e g i n a t r i a l and t h e s u b j e c t a d j u s t e d t h e a m p l i t u d e u n t i l i t matched t h e v i s u a l r e f e r e n t . S u b j e c t ' s a d j u s t e m e n t s had no e f f e c t on t h e phase r e l a t i o n s h i p between v i s u a l and s i m u l a t o r mot i6n which were synchron ized t o w i t h i n 5 m s .

F i g u r e 2 . The SIGMA p r o c e d u r e .

S i x s u b j e c t s p a r t i c i p a t e d i n t h e m a t c h i n g t a s k - - t h r e e m a l e s and t h r e e f e m a l e s . Each s u b j e c t p a r t i c i p a t e d i n two phases . I n Phase I , s u b j e c t s were p r e s e n t e d w i t h s i x r e f e r e n c e s i g n a l s . These s i g n a l s were c o n s t r u c t e d from a c o m b i n a t i o n o f t h r e e f r e q u e n c i e s (0.08 Hz, 0.25 Hz, 0.80 H z ) a n d two a m p l i t u d e s (f2O, ? jO) . P h a s e I c o n s i s t e d o f f o u r s e s s i o n s , two s e s s i o n s i n t h e ALCOGS and two s e s s i o n s i n t h e RATS. The o r d e r o f s i m u l a t o r exposure was b a l a n c e d a c r o s s s u b j e c t s . A s e s s i o n c o n s i s t e d o f s i x t r i a l s , o n e t r i a l f o r each combinat ion o f f r equency and a n g u l a r ampl i tude . The o r d e r of c o n d i t i o n s was a l s o b a l a n c e d a c r o s s s u b j e c t s . A t r i a l began w i t h t h e p r e s e n t a t i o n o f t h e .

v i s u a l s t i m u l u s and zero movement of t h e motion cu ing device . A t r i a l ended when t h e s u b j e o t was s a t i s f i e d t h a t t h e mo t ion o f t h e s i m u l a t o r matched t h e m o t i o n of t h e v i s u a l d i s p l a y . T r i a l d u r a t i o n was n o t c o n t r o l l e d ; however , t r i a l s t y p i c a l l y took less than two minutes. Phase I1 was i d e n t i c a l t o Phase I with t h e excep t ion t h a t a new set of f r equenc i e s was examined (0.16 Hz, 0.48 Hz, 1.11 Hz).

R e s u l t s

The d a t a c o l l e c t e d from t h e matching t a s k were t h e ga in r a t i o s between the v i s u a l r e f e r e n o e a n g u l a r ampl i tude and t h e a n g u l a r ampl i tude s e l e c t e d by t h e s u b j e c t s for the two m o t i o n d e v i o e s (GAIN r AMPHOT N / A M P Y L S U y ) . For example, if t h e v i s u a l r e f e r e n c e s i g n a l ampl i tude was 18, a ga n va ue of .5 would i n d i c a t e t h a t t h e s u b j e c t ad jus t ed the motion dev ice ampli tude to 10.

F i g u r e 3 s h o w s . t h e r e s u l t s from t h e m a t c h i n g t a s k . Each o f t h e f o u r graphs i n F igure 3 cor responds t o a p a r t i c u l a r angu la r ampli tude presented i n o n e o f t h e two m o t i o n o u i n g d e v i c e s . I n t h e g r a p h s t h e a m p l i t u d e r a t i o s , measured i n d e c i b e l s , are p l o t t e d a s a func t ion o f frequency. Each po in t is a mean averaged a c r o s s s i x s u b j e c t s and two o b s e r v a t i o n s per sub j ec t .

"1 ALCOGS : 2'

- 0 '0 - 0 3 Frequency

Figure 3. Gain r a t i o s between s imula tor motion and v i s u a l r e f e r ence as measured using SIGMA.

20-

lo- 9

Z O . -10

-20

20r RATS : 2'

U ) -

i Pi t i , - n y Frequency z O . u 3 008 a36 048 1.11 Hz - 025 080 -10

- -20-

RATS t So

- t )

Frequency - - 0.03 036 048 111 Hz

0 2 5 a80

T h e s e g r a p h s o f amp1 i t u d e - r a t i o s a c r o s s f r e q u e n c i e s w i l l be t r e a t e d a s q u a s i- B o d e p l o t s . They a re q u a s i i n t h a t t h e y i n c l u d e o n l y t h e g a i n r a t i o s s i n c e t h e phase r e l a t i o n s h i p s h a v e been t o t a l l y c o n s t r a i n e d . Two f e a t u r e s o f t h e s e d a t a s h o u l d be noted. F i r s t , w i t h i n mot ion d e v i c e s t h e o v e r a l l p a t t e r n o f g a i n a c r o s s f r e q u e n c y i s r e l a t i v e l y c o n s i s t e n t f o r t h e two r e f e r e n c e ampl i tudes . Second, f o r judgments i n both motion d e v i c e s t h e r e was a tendency f o r g a i n t o d e c r e a s e a s t h e a m p l i t u d e o f t h e r e f e r e n c e s i g n a l i n c r e a s e d .

S i n c e t h e o v e r a l l p a t t e r n d i d n o t change w i t h a m p l i t u d e , and s i n c e human o p e r a t o r s a r e c a p a b l e of a d a p t i n g t o a w i d e r a n g e o f d i s p l a y g a i n s ( F r o s t , 19721, t h e d a t a f o r each s i m u l a t o r were a v e r a g e d a c r o s s t h e two a m p l i t u d e s a t e a o h f r e q u e n o y f o r e a o h i n d i v i d u a l subjeat. W i t h i n i n d i v i d u a l s u b j e c t s , a r a t i o was c a l c u l a t e d between g a i n s measured f o r t h e 8 u b j e c t i n t h e ALCOGS and t h e RATS. T h e s e g a i n s w e r e t h e n a v e r a g e d a c r o s a s u b j e c t s and a r e shown i n F i g u r e 4.

Figure 4. Gain ratios between ALCOGS (G2) and RATS (GI).

The a m p l i t u d e p a t t e r n shown i n F i g u r e 4 was f i t g r a p h i c a l l y w i t h a f i r s t - o r d e r l e a d w i t h a t i m e c o n s t a n t o f 1/6.0 and a g a i n o f .67. T h i s is shown a s t h e s o l i d l i n e i n F i g u r e 4. T h i s l e a d term was t h e n used t o d r i v e t h e ALCOGS sea t- pan f o r u s e i n a r o l l - a x i s t r a c k i n g t ask .

ROLL- AXIS TRACKING TASK

To test t h e h y p o t h e s i s t h a t p o s i t i v e t r a n s f e r . between t h e ALCOGS and t h e RATS c o u l d be i m p r o v e d by i n c r e a s i n g t h e s u b j e c t i v e match b e t w e e n m o t i o n q u a l i t y i n the two s i m u l a t o r s , performance in a r o l l - a x i s t r a c k i n g task was ' m e a s u r e d , S u b j e c t s were t r a i n e d i n t h e ALCOGS u s i n g t h e new a l g o r i t h m , ( d e r i v e d u s i n g t h e SIGMA methodology) t o d r i v e t h e seat- pan. S u b j e c t s were t h e n t r a n s f e r r e d t o t h e RATS t o a s s e s s t h e t r a i n i n g b e n e f i t s o f t h e new a l g o r i t h m .

Procedure

F o u r o f t h e s i x s u b j e c t s who p a r t i c i p a t e d i n t h e m a t c h i n g p h a s e o f t h i s s t u d y c o n t i n u e d i n t o t h e t r a c k i n g p h a s e . T h e i r t a s k e n t a i l e d m a i n t a i ' n i n g w i n g s- l e v e l f l i g h t i n t h e p resence o f a r o l l g u s t d i s t u r b a n c e . T h e t a s k was

i d e n t i c a l t o t h e one d e s c r i b e d by Mar t in (1985- - this volume). S u b j e c t s were t r a i n e d t o n e a r a s y m p t o t e in t h e ALCOGS, w i t h t h e f i r s t - o r d e r l e a d o b t a i n e d f r o m t h e m a t c h i n g p r o c e d u r e a s t h e d r i v e a l g o r i t h m . F o l l o w i n g t r a i n i n g , a u b j s a t s were t r a n s f e r r e d t o an I d e n t i c a l r o l l - a x i s t r a c k i n g t a s k i n t h e RATS t o a s s e s s t h e t r a i n i n g b e n e f i t s from e x p e r i e n c e w i t h motion i n t h e ALCOGS.

R e s u l t s

A c o m p a r i s o n b e t w e e n RMS e r r o r o b t a i n e d i n t h e t r a i n i n g p h a s e o f t h i s exper iment and d a t a p r e v i o u s l y o b t a i n e d by M a r t i n (1985) i s shown i n F i g u r e 5. For t h e p r e s e n t s t u d y each p o i n t was t h e a v e r a g e a c r o s s f o u r s u b J e c t s , whereas t he M a r t i n d a t a were a v e r a g e d a c r o s s s i x s u b j e c t s .

10 - 0 RATS Trotnmq 0 Stotic- No Motion 0 ALCOGS-Postlion o w e Algor~lhrn ALCOCS - Siqmo Alpor~lhm A ALCOGS- Velocily Ortve Alpor~lhm

Figure 5 . RMS e r r o r s c o r e s f o r r o l l - a x i s t r a c k i n g t a s k obtained d u r i n g training.

F i g u r e 5 shows t h a t t h e t r a c k i n g e r r o r o b t a i n e d u s i n g t h e new ALCOGS d r i v e a l g o r i t h m was c l o s e r t o t h e l e v e l o f e r r o r o b t a i n e d f rom M a r t i n ' s (1985) s u b j e c t s t r a i n e d w i t h RATS m o t i o n c u e s t h a n t o s u b j e c l t s t r a i n e d w i t h a 1 t e r n a t i v e ALCOGS d r i v e a l g o r i t h m s (pure p o s i t i o n o r pure v e l o c i t y ) o r wi th no motion cues.

Not o n l y was t h e r e a c l o s e m a t c h be tween t h e RMS e r r o r o b t a i n e d be tween s u b j e c t s t r a i n e d w i t h t h e f i r s t - o r d e r l e a d a l g o r i t h m and s u b j e c t s t r a i n e d i n t h e RATS, b u t p r e l i m i n a r y comparisons of d e s c r i b i n g f u n c t i o n s showed t h a t the f requenoy c h a r a c t e r i s t i c s were a l s o i n agreeement. Gain , phase, and remnant d a t a o b t a i n e d f o r t h e s u b j e c t s u s i n g t h e ALCOGS w i t h t h e new d r i v e a l g o r i t h m w e r e i n n e a r l y p e r f e c t a g r e e m e n t w i t h t h a t o f s u b j e c t s t r a i n e d i n t h e RATS.

' T h i s was n o t t r u e f o r s u b j e c t s t r a i n e d w i t h the,ALCOGS d r i v e a l g o r i t h m s s t u d i e d by M a r t i n (1985). S u b j e c t s t r a i n e d w i t h a p o s i t i o n d r i v e a l g o r i t h m i n t h e ALCOGS showed less phase l e a d t h a n s u b j e c t s t r a i n e d i n t h e RATS. S u b j e o t s t r a i n e d w i t h a v e l o c i t y d r i v e a l g o r i t h m i n t h e ALCdGS showed h i g h e r remnant a t t h e mid- frequenc ies t h a n subjects t r a i n e d i n t h e RATS. F i n a l l y , s u b j e c t s who r e c e i v e d n o m o t i o n c u e s showed c o n s i d e r a b l y l e s s p h a s e l e a d and l o w e r g a i n t h a n s u b d e c t s t r a i n e d i n t h e RATS.

A c o m p a r i s o n b e t w e e n R M S e r r o r o b t a i n e d i n t h e t r a n s f e r p h a s e o f t h i s exper iment and d a t a p r e v i o u s l y o b t a i n e d by Mar t in (1985) i s shown i n F igure 6. T h i s f i g u r e s h o w s t h a t d e s p i t e t h e i m p r o v e d t r a i n i n g p e r f o r m a n c e shown i n

- F-igure 5, t h e r e was n o i m p r o v e m e n t I n t r a n s f e r w i t h - t h e new ALCOGS d r i v e

a l g o r i t h m . T r a n s f e r w i t h t h e new a l g o r i t h m was no o e t t e r t h a n t r a n s f e r f o r t h e o t h e r a l g o r i t h m s s t u d i e d b y M a r t i n ( 1 9 8 5 ) - - i n c l u d i n g t h e no m o t i o n a l g o r i t h m . Thus, t h e h y p o t h e s i s t h a t s u b j e c t i v e matching o f t h e a 1 t e r n a t i v e mot ion d e v i c e s would i n c r e a s e p o s i t i v e t r a n s f e r was n o t suppor ted.

Tronslcr Rots 0 No Troining I C o ~ t o l l 0 Slolic - No Molbn T~roln'kq 0 ALCOGS - Posilion Drive

T~oining a ALCOGS- Velocily Drive

Troining .

0- Sosion J++F+k Session

F i g u r e 6 . RMS e r r o r s c p r e s f o r r o l l - a x i s t r a c k i n g t a s k o b t a i n e d fo l lowing t r a n s f e r t o t h e RATS.

The r e s u l t s from t h i s i n v e s t i g a t i o n p r o v i d e an i n t e r e s t i n g paradox. On t h e o n e h a n d , t h e ALCOGS s e a t - p a n , d r i v e n w i t h t h e S I G M A g e n e r a t e d l e a d a l g o r i t h m a p p e a s s t o h a v e p rov ided s u b J e c t s wi th s i m i l a r i n f o r m a t i o n t o t h a t p r o v i d e d by t h e RATSr E v i d e n c e f o r t h i s comes f r o m t h e s i m i l a r i t y o f e r r o r s c o r e s and f requency - c h a r a c t e r i s t i a s o b t a i n e d by s u b d e c t s i n t h e two t r a i n i n g c o n d i t i o n s . On t h e o t h e r h a n d , t r a n s f e r was no b e t t e r f o r t h i s new m o t i o n a l g o r i t h m t h a n f o r t h a t o b t a i n e d i n a no motion t r a i n i n g c o n d i t i o n .

These p a r a d o x i c a l r e s u l t s demons t ra te two p o i n t s wi th regard t o t r a i n i n g and s i m u l a t i o n . F i r s t , a n i m p o r t a n t requirement of a t r a i n i n g program is t h a t i t d e v e l o p s a t t e n t i o n a l o r s e l e c t i o n s k i l l s . The t r a i n i n g p r o c e d u r e m u s t i n f o r m t h e s t u d e n t a b o u t w h e r e i n t h e e n v i r o n m e n t i m p o r t a n t i n f o r m a t i o n i s l i k e l y t o be p resen ted . P r o v i d i n g e q u i v a l e n t in fo rmat ion i n a m o d a l i t y o r form u n l i k e t h a t o f t h e c r i t e r i o n e n v i r o n m e n t may n o t r e s u l t i n p o s i t i v e t r a n s f e r . A s e c o n d , r e l a t e d p o i n t i s t h a t p e r f o r m a n c e d a t a , e i t h e r i n t h e form o f RMS e r r o r or i n t h e form of q u a l i t a t i v e d e s c r i b i n g f u n c t i o n s , w i l l n o t be a r e l i a b l e p r e d i c t o r o f t h e t r a i n i n g p o t e n t i a l o f a s i m u l a t o r . T h e s e p e r f o r m a n c e d a t a w i l l be s e n s i t i v e t o t h e i n f o r m a t i o n p r o v i d e d by t h e s i m u l a t o r ' , b u t w i l l n o t be s e n s i t i v e t o d i f f e r e n c e s i n t h e way (e.g,, m o d a l i t y ) t h a t i n f o r m a t i o n is presented. The p o i n t i s p a r t i c u l a r l y impor tan t f o r t h e assessment o f motion-base s i m u l a t o r s i n a v i a t i o n t r a i n i n g , s i n c e it is v e r y d i f f i c u l t t o d u p l i c a t e t h e p a t t e r n o f v e s t i b u l a r and t a c t i l e s t i m u l a t i o n exper ienced i n a c t u a l f l i g h t env i ronments w i t h a ground based s i m u l a t o r .

Al though t h e SIGMA methodology was u n s u c c e s s f u l wi th r e g a r d s t o improving t r a n s f e r i n t h i s s t u d y , t h e r e s u l t s s u g g e s t t h a t i t may be a u s e f u l methodology f o r s u b j e c t i v e l y e q u a t i n g dynamic i n f o r m a t i o n d i s p l a y s . F i r s t , i t y i e l d e d d a t a i n a fo rm ( l i n e a r d i f f e r e n t i a l e q u a t i o n ) u s e f u l f o r m o d i f y i n g e l e c t r o- m e c h a n i c a l i n f o r m a t i o n d i s p l a y s . S e c o n d , t h e m o d i f i c a t i o n s d e r i v e d

performance f o r two a l t e r n a t i v e motion d i sp lays . Much a d d i t i o n a l research w i l l be required t o v a l i d a t e t h i s methodology, however, before it is judged t o be a u s e f u l e x t e n s i o n o f S t e v e n s t (1975) r e s e a r c h on p s y c h o p h y s i c a l measurement.

ACKNOWLEDGMENT

T h i s r e s e a r c h was conducted w h i l e John F l a c h was a f e l l o w i n t h e SGEEE- AFOSR Summer Fellowship program.

REFERENCES

F r o s t , G. (1972). Man-machine Dynamics. I n H.P. VanCott and R.G. Kinkade (Eds.), Human e n g i n e e r i n g ~ u i d 0 to equipment d e s i g n (pp. 227-3091, Washington, DC: . American I n s t i t u t e f o r Research.

Kle inwaks , J .M. (1980, January) . Advanced low c o s t g- cuing sys tem (ALCOGS). A i r Force Human Resources Laboratory, AFHRL-TR-~~-~~. -

L e v i s o n , W.H., M c M i l l a n , G.R., & M a r t i n , E.A. (1984, June) . Models f o r t h e e f f e o t s of g- s e a t c u i n g on r o l l - a x i s t r a c k i n g performanae. Twent i e th Annual Conferenoe on Manual Control. Cal i fornia : NASA-ARC.

M a r t i n , E.A. (1985, A p r i l ) . An i n v e s t i g a t i o n r e g a r d i n g t h e uae o f a dynamio seat-pan d i s p l a y f o r t r a i n i n g and a s a device f o r communicating r o l l - a x i s motion i n f o r m a t i o n . P r o c e e d i n g s of t h e T h i r d Symposium on A v i a t i o n Psyoholoay. Columbus, OH.

McMi l l an , G.R. , L e v i s o n , W.H., & M a r t i n , E.A. (1984, A p r i l ) . Motion s i m u l a t i o n w i t h .a g- s e a t system: Sensory and performance mechanisms. Proceedings_ o f t h e Nin th P s y c h o l o ~ y i n t h e DOD Symposium (pp. 158-162). Colorado Springs, CO: U.S. A i r Force Academy.

Stevens, S.S. (1975). Psychophysics. New York: John Wiley & Sons.