The perceptual asymmetry (PA) effect

Two c a s e s t u d i e s o f what w i l l be r e f e r r e d to a s t h e P e r c e p t u a l Asymmetry (PA) E f f e c t w i l l be in t roduced : 1) t h e n o l l a h a l l o n e f f e c t i n h e a r i n g and 2 ) t h e p e r c e p t u a l f o c u s i n g e f f e c t i n v i s i o n . The f o r m e r c a s e i s a s p i n o f f f rom a n evaluat ion of d i g i t ma te r i a l f o r Automatic Speech Recognition ASR where in t h e Swedish d i g i t ' no l l a ' ( z e r o ) is t r a n s f o r m e d i i n t o ' h a l l o n ' ( r a s p b e r r y ) i n r e v e r s e d p l a y b a c k . The weak a s p i r a t o r y n o i s e segment t e r m i n a t i n g t h e ' no l l a ' spect rum ( t h e physiological explanation o f which is a gradual g l o t t a l abduction g e s t u r e ) is p e r c e p t u a l l y n e g l e c t e d i n normal p layback, b u t i s perceptual ly de tec ted i n reversed playback. Two main hypotheses a r e advanced: (1) t h e forward masking h y p o t h e s i s and ( 2 ) t h e l i n g u i s t i c s t r u c t u r e dominance hypothesis, (da ta predic t ion) . The experiments conducted advocate, wi t h some reservat ion , hypothesis No 2. -The l a t t e r c a s e i s l i k e w i s e a s p i n o f f , t h i s t i m e from r e s e a r c h i n P e r c e p t i o n Physio logy and A r t Theory. I n a t a r g e t space r e l a t i o n t h e t a r g e t o b j e c t i s a c t i n g a s a masker w i t h f luc tua t ing influence on the p e r c e p t s o f t h e su r round ing space . The exper iment shows t h a t it i s n o t p o s s i b l e t o p r e d i c t t h e i n t e r p r e t a t i o n o f a g i v e n o p t i c a l s i g n a l on t h e b a s i s of a physical ana lys i s of t h e s p e c t r a l components alone. The two case s t u d i e s i n d i c a t e a funct ional s i m i l a r i t y i n t h e two senses, and focus upon t h e i n t r i c a t e r e l a t i o n between fea tu re de tec t ion and f e a t u r e decoding.