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Lookup NU author(s): Dr Andrew Welchman, Professor Julie Harris
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Retinal activity is the first stage of visual perception. Retinal sampling is non-uniform and not continuous, yet visual experience is not characterized by holes and discontinuities in the world. How does the brain achieve this perceptual completion? Fifty years ago, it was suggested that visual perception involves a two-stage process of (i) edge detection followed by (ii) neural filling-in of surface properties. We examine whether this general hypothesis can account for the specific example of perceptual completion of a small target surrounded by dynamic dots (an 'artificial scotoma'), a phenomenon argued to provide insight into the mechanisms responsible for perception. We degrade the target's borders using first blur and then depth continuity, and find that border degradation does not influence time to target disappearance. This indicates that important information for the continuity of target perception is conveyed at a coarse spatial scale. We suggest that target disappearance could result from adaptation that is not specific to borders, and question the need to hypothesize an active filling-in process to explain this phenomenon.
Author(s): Welchman AE, Harris JM
Publication type: Article
Publication status: Published
Journal: Proceedings of the Royal Society B: Biological Sciences
Year: 2003
Volume: 270
Issue: 1510
Pages: 83-90
ISSN (print): 0962-8436
ISSN (electronic): 1471-2970
Publisher: The Royal Society Publishing
URL: http://dx.doi.org/10.1098/rspb.2002.2220
DOI: 10.1098/rspb.2002.2220
PubMed id: 12590775
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