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Visual Search and Visual Inspection Introduction
Theoretical and Applied Aspects of Eye Movement Research A.G. Gale and F. Johnson (Editors) 0 Elsevier Science Publishers B.V. (North-Holland), 1984
333
VISUAL SEARCH AND VISUAL INSPECTION INTRODUCTION Murray A. S i n c l a i r Department o f Human Sciences, Loughborough U n i v e r s i t y o f Technology, Loughborough, England. I n t h e s e c t i o n a r e g a t h e r e d t o g e t h e r a number o f papers a d d r e s s i n g v i s u a l search. They c o v e r t h e r a n g e o f problems, f r o m i n v e s t i g a t i o n s o f i n f o r m a t i o n - p r o c e s s i n g w i t h i n t h e o b s e r v e r (Mockel & Heemsoth, Nattkemper & P r i n z ) t h r o u g h a d i s c u s s i o n o f methods o f measuring v i s u a l lobes (Bellamy) t o a p p l i e d work where search i s a c t i v e l y i n v o l v e d as a v i t a l component o f o p e r a t o r performance w i t h i n systems ( H i l l e n , Papin and S i n c l a i r ) . I n t h e more t h e o r e t i c a l papers, Mockel and Heemsoth d i s c u s s t h e importance o f p r i o r i n f o r m a t i o n i n c o n t r o l l i n g t h e d i r e c t i o n o f gaze; i n t h e i r case i t i s knowledge o f what t o l o o k f o r t h a t c o n t r o l s where t h e o b s e r v e r l o o k s i n t h e a c q u i s i t i o n o f knowledge t o assess performance. They chose a moving i n f o r m a t i o n d i s p l a y (an a t h l e t e ) , t h e r e b y e n s u r i n g t h a t t h e l o c u s o f maximum i n f o r m a t i o n i n t h e v i s u a l f i e l d was c o n t i n u a l l y changing. T h i s i s a c l e v e r i d e a , w o r t h y o f f u r t h e r use. T h e i r r e s u l t s i n d i c a t e t h a t t h e gaze i s i n d e e d d i r e c t e d more e f f i c i e n t l y t h e more one knows about t h e t a s k , as m i g h t be expected. Nattkemper and P r i n z d i s c u s s t h e e f f e c t s o f redundancy i n a l e t t e r - m a t r i x search t a s k . T h e i r i n i t i a l h y p o t h e s i s i s t h a t t h e more p r e d i c t a b l e i s t h e sequence o f n o n - t a r g e t l e t t e r s , t h e f a s t e r w i l l search o c c u r f o r t h e t a r g e t l e t t e r . Revising t h i s hypothesis r a p i d l y i n t h e l i g h t o f t h e i r r e s u l t s , t h e y conclude t h a t redundancy does i n d e e d h e l p , once t h e r u l e s g o v e r n i n g t h e redundancy have been mastered. They pose t h e q u e s t i o n o f how l o n g i t t a k e s t o l e a r n s u c h s y n t a c t i c a l r u l e s ; one suspects t h a t t h e answer has been p r o v i d e d b y S h i f f r i n and Schneider (1977) and Schneider and S h i f f r i n (1977) w i t h t h e l e a r n i n g p l a t e a u o c c u r r i n g a f t e r some thousand t r i a l s . The paper i n d i c a t e s r a t h e r w e l l t h a t t h e c o m p l e x i t i e s o f search go beyond t h e u s u a l two- o r t h r e e - v a r i a b l e paradigms so o f t e n s t u d i e d i n t h e l a b o r a t o r y . B e l l a m y ' s paper i s m a i n l y a r e v i e w paper, w i t h a b r i e f r e p o r t o f some e x p e r i m e n t s she has c a r r i e d o u t . The problem t h a t has b e s e t her, and many others concerned w i t h r e a l - l i f e t a s k s , i s how t o p r e d i c t performance i n a search t a s k . F r e q u e n t l y , t h e aim i s t o e s t a b l i s h a performance norm, u s u a l l y embodying n o t i o n s o f t h e ' I d e a l O p e r a t o r ' , which can a c t as a r e f e r e n c e p o i n t a g a i n s t which human ( o r machine) performance can be compared. The common approach i s t o b u i l d a model i n which t h e concept o f t h e ' v i s u a l lobe' plays a prominent p a r t . The problem t h e n becomes one o f a s s e s s i n g t h e s i z e o f t h i s v i s u a l lobe, and t h e n i n c l u d i n g i t i n a search s t r a t e g y t o p r e d i c t performance. The main p a r t o f h e r paper i s concerned w i t h t h e assessment o f s i z e and h e r d i s c u s s i o n o f methods t o do t h i s i s l i n k e d w i t h o v e r a l l performance measures. I t i s a v e r y u s e f u l s h o r t review. The r e s t o f t h e papers a r e f a r more a p p l i e d . H i l l e n d i s c u s s e s t h e problem o f measu r i n g search performance i n t h e i n s p e c t i o n o f d e s s e r t apples. T h i s t a s k i s f a i r l y t y p i c a l o f conveyor-paced i n s p e c t i o n tasks, d i f f e r i n g f r o m manuf a c t u r i n g t a s k s i n t h a t t h e a p p l e s a r e r o t a t i n g and a r e l e s s u n i f o r m . He p r o v i d e s a s u c c i n c t d e s c r i p t i o n o f t h e d i f f i c u l t i e s t h a t may be encountered i n practice.
334
M.A. Sinclair
Papin p r e s e n t s a d i g e s t o f h i s work o v e r a number o f y e a r s . He has been concerned w i t h i n f o r m a t i o n - p r o c e s s i n g by p i l o t s and t h e search s t r a t e g i e s t h e y use. T h i s i s a p r a c t i c a l v e r s i o n of t h e paradigm i n v e s t i g a t e d by Mockel and Heemsoth and h i s r e s u l t s converge t o t h e same g e n e r a l conclusion; e x p e r t s a r e more s k i l l e d i n t h e i r search f o r r e l e v a n t i n f o r m a t i o n t h a n n o v i c e s . He t h e n goes on t o d i s c u s s h i s c u r r e n t work, i n which he i s t r y i n g t o b u i l d h i s more s p e c i f i c c o n c l u s i o n s i n t o t r a i n i n g programs f o r p i l o t s . With simulators,or without, p i l o t t r a i n i n g i s very resourcei n t e n s i v e and h i s a t t e m p t t o o p t i m i s e t r a i n i n g e f f e c t i v e n e s s i s t o be commended. F i n a l l y , S i n c l a i r discusses a q u a l i t y i n s p e c t i o n t a s k i n t h e aerospace i n d u s t r y where t h e management were c o n t e m p l a t i n g t h e i n t r o d u c t i o n o f an e l e c t r o - o p t i c a l d e v i c e t o r e p l a c e some human i n s p e c t o r s . The paper r e p o r t s t h e r e s u l t o f a comparison study, and comes t o t h e c o n c l u s i o n t h a t a symbio s i s between man and machine p r o b a b l y r e p r e s e n t s t h e b e s t approach; t h e e l e c t r o n i c d e v i c e , a l b e i t a p r o t o t y p e , does n o t match human performance and cannot a t t a i n t h e r e q u i r e d q u a l i t y performance e i t h e r . Taken as a group, t h e papers i l l u s t r a t e t h e problems o f r e s e a r c h i n t h i s f i e l d , and t h e lacuna between p u r e and a p p l i e d r e s e a r c h . Given t h e e f f o r t c u r r e n t l y b e i n g expended i n b o t h human and r o b o t v i s i o n , i t i s t o be hoped t h a t t h e main gap, t h a t o f q u a n t i t a t i v e models o f t h e o b s e r v e r , w i l l soon close. Refe r e n ce s Schneider, W. and S h i f f r i n , R.M. 1977. C o n t r o l l e d and a u t o m a t i c human i n f o r m a t i o n p r o c e s s i n g : I D e t e c t i o n , search and a t t e n t i o n . Psychol. Rev. 8 4 ( 1 ) , 1-66. S h i f f r i n , R.M. and Schneider, W., 1977. C o n t r o l l e d and a u t o m a t i c human i n f o r m a t i o n p r o c e s s i n g : I1 P e r c e p t u a l l e a r n i n g , a u t o m a t i c a t t e n d i n g and a g e n e r a l t h e o r y . P s y c h o l . Rev. 8 4 ( 2 ) . 127-190.
333
VISUAL SEARCH AND VISUAL INSPECTION INTRODUCTION Murray A. S i n c l a i r Department o f Human Sciences, Loughborough U n i v e r s i t y o f Technology, Loughborough, England. I n t h e s e c t i o n a r e g a t h e r e d t o g e t h e r a number o f papers a d d r e s s i n g v i s u a l search. They c o v e r t h e r a n g e o f problems, f r o m i n v e s t i g a t i o n s o f i n f o r m a t i o n - p r o c e s s i n g w i t h i n t h e o b s e r v e r (Mockel & Heemsoth, Nattkemper & P r i n z ) t h r o u g h a d i s c u s s i o n o f methods o f measuring v i s u a l lobes (Bellamy) t o a p p l i e d work where search i s a c t i v e l y i n v o l v e d as a v i t a l component o f o p e r a t o r performance w i t h i n systems ( H i l l e n , Papin and S i n c l a i r ) . I n t h e more t h e o r e t i c a l papers, Mockel and Heemsoth d i s c u s s t h e importance o f p r i o r i n f o r m a t i o n i n c o n t r o l l i n g t h e d i r e c t i o n o f gaze; i n t h e i r case i t i s knowledge o f what t o l o o k f o r t h a t c o n t r o l s where t h e o b s e r v e r l o o k s i n t h e a c q u i s i t i o n o f knowledge t o assess performance. They chose a moving i n f o r m a t i o n d i s p l a y (an a t h l e t e ) , t h e r e b y e n s u r i n g t h a t t h e l o c u s o f maximum i n f o r m a t i o n i n t h e v i s u a l f i e l d was c o n t i n u a l l y changing. T h i s i s a c l e v e r i d e a , w o r t h y o f f u r t h e r use. T h e i r r e s u l t s i n d i c a t e t h a t t h e gaze i s i n d e e d d i r e c t e d more e f f i c i e n t l y t h e more one knows about t h e t a s k , as m i g h t be expected. Nattkemper and P r i n z d i s c u s s t h e e f f e c t s o f redundancy i n a l e t t e r - m a t r i x search t a s k . T h e i r i n i t i a l h y p o t h e s i s i s t h a t t h e more p r e d i c t a b l e i s t h e sequence o f n o n - t a r g e t l e t t e r s , t h e f a s t e r w i l l search o c c u r f o r t h e t a r g e t l e t t e r . Revising t h i s hypothesis r a p i d l y i n t h e l i g h t o f t h e i r r e s u l t s , t h e y conclude t h a t redundancy does i n d e e d h e l p , once t h e r u l e s g o v e r n i n g t h e redundancy have been mastered. They pose t h e q u e s t i o n o f how l o n g i t t a k e s t o l e a r n s u c h s y n t a c t i c a l r u l e s ; one suspects t h a t t h e answer has been p r o v i d e d b y S h i f f r i n and Schneider (1977) and Schneider and S h i f f r i n (1977) w i t h t h e l e a r n i n g p l a t e a u o c c u r r i n g a f t e r some thousand t r i a l s . The paper i n d i c a t e s r a t h e r w e l l t h a t t h e c o m p l e x i t i e s o f search go beyond t h e u s u a l two- o r t h r e e - v a r i a b l e paradigms so o f t e n s t u d i e d i n t h e l a b o r a t o r y . B e l l a m y ' s paper i s m a i n l y a r e v i e w paper, w i t h a b r i e f r e p o r t o f some e x p e r i m e n t s she has c a r r i e d o u t . The problem t h a t has b e s e t her, and many others concerned w i t h r e a l - l i f e t a s k s , i s how t o p r e d i c t performance i n a search t a s k . F r e q u e n t l y , t h e aim i s t o e s t a b l i s h a performance norm, u s u a l l y embodying n o t i o n s o f t h e ' I d e a l O p e r a t o r ' , which can a c t as a r e f e r e n c e p o i n t a g a i n s t which human ( o r machine) performance can be compared. The common approach i s t o b u i l d a model i n which t h e concept o f t h e ' v i s u a l lobe' plays a prominent p a r t . The problem t h e n becomes one o f a s s e s s i n g t h e s i z e o f t h i s v i s u a l lobe, and t h e n i n c l u d i n g i t i n a search s t r a t e g y t o p r e d i c t performance. The main p a r t o f h e r paper i s concerned w i t h t h e assessment o f s i z e and h e r d i s c u s s i o n o f methods t o do t h i s i s l i n k e d w i t h o v e r a l l performance measures. I t i s a v e r y u s e f u l s h o r t review. The r e s t o f t h e papers a r e f a r more a p p l i e d . H i l l e n d i s c u s s e s t h e problem o f measu r i n g search performance i n t h e i n s p e c t i o n o f d e s s e r t apples. T h i s t a s k i s f a i r l y t y p i c a l o f conveyor-paced i n s p e c t i o n tasks, d i f f e r i n g f r o m manuf a c t u r i n g t a s k s i n t h a t t h e a p p l e s a r e r o t a t i n g and a r e l e s s u n i f o r m . He p r o v i d e s a s u c c i n c t d e s c r i p t i o n o f t h e d i f f i c u l t i e s t h a t may be encountered i n practice.
334
M.A. Sinclair
Papin p r e s e n t s a d i g e s t o f h i s work o v e r a number o f y e a r s . He has been concerned w i t h i n f o r m a t i o n - p r o c e s s i n g by p i l o t s and t h e search s t r a t e g i e s t h e y use. T h i s i s a p r a c t i c a l v e r s i o n of t h e paradigm i n v e s t i g a t e d by Mockel and Heemsoth and h i s r e s u l t s converge t o t h e same g e n e r a l conclusion; e x p e r t s a r e more s k i l l e d i n t h e i r search f o r r e l e v a n t i n f o r m a t i o n t h a n n o v i c e s . He t h e n goes on t o d i s c u s s h i s c u r r e n t work, i n which he i s t r y i n g t o b u i l d h i s more s p e c i f i c c o n c l u s i o n s i n t o t r a i n i n g programs f o r p i l o t s . With simulators,or without, p i l o t t r a i n i n g i s very resourcei n t e n s i v e and h i s a t t e m p t t o o p t i m i s e t r a i n i n g e f f e c t i v e n e s s i s t o be commended. F i n a l l y , S i n c l a i r discusses a q u a l i t y i n s p e c t i o n t a s k i n t h e aerospace i n d u s t r y where t h e management were c o n t e m p l a t i n g t h e i n t r o d u c t i o n o f an e l e c t r o - o p t i c a l d e v i c e t o r e p l a c e some human i n s p e c t o r s . The paper r e p o r t s t h e r e s u l t o f a comparison study, and comes t o t h e c o n c l u s i o n t h a t a symbio s i s between man and machine p r o b a b l y r e p r e s e n t s t h e b e s t approach; t h e e l e c t r o n i c d e v i c e , a l b e i t a p r o t o t y p e , does n o t match human performance and cannot a t t a i n t h e r e q u i r e d q u a l i t y performance e i t h e r . Taken as a group, t h e papers i l l u s t r a t e t h e problems o f r e s e a r c h i n t h i s f i e l d , and t h e lacuna between p u r e and a p p l i e d r e s e a r c h . Given t h e e f f o r t c u r r e n t l y b e i n g expended i n b o t h human and r o b o t v i s i o n , i t i s t o be hoped t h a t t h e main gap, t h a t o f q u a n t i t a t i v e models o f t h e o b s e r v e r , w i l l soon close. Refe r e n ce s Schneider, W. and S h i f f r i n , R.M. 1977. C o n t r o l l e d and a u t o m a t i c human i n f o r m a t i o n p r o c e s s i n g : I D e t e c t i o n , search and a t t e n t i o n . Psychol. Rev. 8 4 ( 1 ) , 1-66. S h i f f r i n , R.M. and Schneider, W., 1977. C o n t r o l l e d and a u t o m a t i c human i n f o r m a t i o n p r o c e s s i n g : I1 P e r c e p t u a l l e a r n i n g , a u t o m a t i c a t t e n d i n g and a g e n e r a l t h e o r y . P s y c h o l . Rev. 8 4 ( 2 ) . 127-190.