title: Induction of Kanizsa Contours Requires Awareness of the Inducing Context.
abstract: It remains unknown to what extent the human visual system interprets information about complex scenes without conscious analysis. Here we used visual masking techniques to assess whether illusory contours (Kanizsa shapes) are perceived when the inducing context creating this illusion does not reach awareness. In the first experiment we tested perception directly by having participants discriminate the orientation of an illusory contour. In the second experiment, we exploited the fact that the presence of an illusory contour enhances performance on a spatial localization task. Moreover, in the latter experiment we also used a different masking method to rule out the effect of stimulus duration. Our results suggest that participants do not perceive illusory contours when they are unaware of the inducing context. This is consistent with theories of a multistage, recurrent process of perceptual integration. Our findings thus challenge some reports, including those from neurophysiological experiments in anaesthetized animals. Furthermore, we discuss the importance to test the presence of the phenomenal percept directly with appropriate methods.
authors: Experimental Psychology, University College London, 26 Bedford Way, London, United Kingdom.
authors: Theodora
authors: T
authors: Banica
authors: Experimental Psychology, University College London, 26 Bedford Way, London, United Kingdom.|Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, United Kingdom.
authors: D Samuel
authors: DS
authors: Schwarzkopf
mesh_terms: D000293:Adolescent; D000328:Adult; D003198:Computer Simulation; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D007088:Illusions / Q000502:physiology*; D008297:Male; D008960:Models, Psychological; D010364:Pattern Recognition, Visual / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult