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Recognising objects and faces. General problems Given that objects move on a surface, why do they not appear to change shape? How do we recognise objects.

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Presentation on theme: "Recognising objects and faces. General problems Given that objects move on a surface, why do they not appear to change shape? How do we recognise objects."— Presentation transcript:

1 Recognising objects and faces

2 General problems Given that objects move on a surface, why do they not appear to change shape? How do we recognise objects that we can only partially see? How do we extract the definitive properties of each object from stimulation on the retina? How do we match the definitive object properties to a stored item in long-term memory (LTM)?

3 How do we refer to these problems? shape constancy occlusion extracting the definitive properties finding a match in LTM

4 Basic theoretical accounts of object representation Templates and Alignment theories (e.g., Ullman, 1989; Bülthoff & Edelman, 1992)

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11 Features (Selfridge, 1961).

12 Structural descriptions (e.g. Marr, 1982)

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14 Part-based theories (e.g., Marr & Nishihara, 1978; Biederman, 1987)

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18 Representing faces Faces as wholes not parts (in contrast to houses) Effect of inversion on face processing (in contrast to houses)

19 Effects of probe type (Tanaka and Farah, 1993; Donnelly and Davidoff, 1999)

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21 Scrambled stimuli

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23 Effects of inversion on face processing

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29 References Biederman, I. (1987). Recognition-by-components: A theory of human image understanding. Psychological Review, 94, 115-147. Brown, J. M., Weisstien, N. and May, J. G. (1992) Visual search for simple volumetric shapes. Perception and Psychophysics, 51, 40-48. Bülthoff, H. H. and Edelman, S. (1992). Psychophysical support for a two-dimensional view interpolation theory of object recognition. Proceedings of the National Academy of Sciences, 89, 60-64. Donnelly, N. and Davidoff, J. B. (1999). The mental representations of faces and houses: Issues concerning wholes and parts. Visual Cognition, 6, 319-343. Marr, D. (1982). Vision. W. H. Freeman: San Francisco Marr, D. and Nishihara, N. K. (1978). Representation and recognition of the spatial organization of three-dimensional shapes. Proceedings of the Royal Society of London: Series B, 200, 269- 294. Palmer, S. E. (1999).Vision Science: From Photons to Phenomenology. MIT Press: Cambridge, MA Tanaka, J. and Farah, M. (1993). Parts and wholes in face recognition. Quarterly Journal of Experimental Psychology, 46A, 225-245. Ullman, S. (1989). Aligning pictorial descriptions: An approach to object recognition. Cognition, 32, 193-254.


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