Induction of Kanizsa contours requires awareness 1

10 11 It BLOCKINremains BLOCKINunknown BLOCKINto BLOCKINwhat BLOCKINextent BLOCKINthe BLOCKINhuman BLOCKINvisual BLOCKINsystem BLOCKINinterprets BLOCKINinformation 12 about complex scenes without conscious analysis. Here we used visual masking 13 techniques BLOCKINto BLOCKINassess BLOCKINwhether BLOCKINillusory BLOCKINcontours BLOCKIN(Kanizsa BLOCKINshapes) BLOCKINare BLOCKINperceived BLOCKINwhen 14 the BLOCKINinducing BLOCKINcontext BLOCKINcreating BLOCKINthis BLOCKINillusion BLOCKINdoes BLOCKINnot BLOCKINreach BLOCKINawareness. BLOCKINIn BLOCKINexperiment BLOCKIN1 15 we BLOCKINtested BLOCKINperception BLOCKINdirectly BLOCKINby BLOCKINhaving BLOCKINparticipants BLOCKINdiscriminate BLOCKINthe BLOCKINorientation BLOCKINof 16 an illusory contour. In experiment 2, we probed perception indirectly by using 17 Kanizsa shapes to prime performance on a visual search task. In experiment 3, we 18 exploited BLOCKINthe BLOCKINfact BLOCKINthat BLOCKINthe BLOCKINpresence BLOCKINof BLOCKINan BLOCKINillusory BLOCKINcontour BLOCKINenhances BLOCKINperformance BLOCKINon 19 a spatial localization task. Moreover, in experiment 3 we also used a different 20 masking BLOCKINmethod BLOCKINto BLOCKINrule BLOCKINout BLOCKINthe BLOCKINeffect BLOCKINof BLOCKINstimulus BLOCKINduration. BLOCKINOur BLOCKINresults BLOCKINsuggest BLOCKINthat 21 participants do not perceive illusory contours when they are unaware of the 22 inducing context. While perceptual grouping and surface segmentation may occur 23 without awareness of the stimuli, the induction of the phenomenal percept of an 24 illusory shape does not. This is consistent with theories of a multistage, recurrent 25 process of perceptual integration. Our findings thus challenge some reports, 26 including those from neurophysiological experiments in anaesthetized animals. We 27 discuss BLOCKINthe BLOCKINimportance BLOCKINto BLOCKINtest BLOCKINthe BLOCKINpresence BLOCKINof BLOCKINthe BLOCKINphenomenal BLOCKINpercept BLOCKINdirectly BLOCKINwith 28 appropriate BLOCKINmethods. 29 30 Keywords 31 32 Illusory BLOCKINcontours, BLOCKINmodal BLOCKINcompletion, BLOCKINawareness, BLOCKINmasking 33 34 35 36. CC-BY-NC 4.0 International license not peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was. 2 Introduction 37 38 What role does conscious processing of the environment fulfill and how much 39 processing occurs in the absence of awareness? It is self-evident that much of the 40 internal bodily functions and controlling learned motor behaviors, like walking or 41 driving, operate mostly without awareness. But for processing by the classical 42 senses, BLOCKINlike BLOCKINvision, BLOCKINthere BLOCKINhave BLOCKINbeen BLOCKINwidely BLOCKINdiscrepant BLOCKINfindings BLOCKINon BLOCKINhow BLOCKINmuch BLOCKINstimulus 43 processing can occur and how much it affects decision-making when the subject is 44 unaware BLOCKINof BLOCKINthe BLOCKINstimulus. BLOCKINThe BLOCKINapproach BLOCKINwith BLOCKINwhich BLOCKINunconscious BLOCKINstimulus BLOCKINprocessing 45 is BLOCKINstudied BLOCKINhas BLOCKINalso BLOCKINbeen BLOCKINsubject BLOCKINto BLOCKINcontroversy BLOCKIN[1]. 46 47 Several experiments suggest that the effect of a contextual stimulus on a target, 48 such BLOCKINas BLOCKINin BLOCKINthe BLOCKINtilt BLOCKINillusion BLOCKINor BLOCKINadaptation BLOCKINeffects, BLOCKINpersists BLOCKINeven BLOCKINwhen BLOCKINparticipants BLOCKINare 49 unaware …