Like comparing apples and oranges: A reinterpretation of categorical face aftereffects

Katherine Storrs (2011). Like comparing apples and oranges: A reinterpretation of categorical face aftereffects Honours Thesis, School of Psychology, The University of Queensland.

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Author Katherine Storrs
Thesis Title Like comparing apples and oranges: A reinterpretation of categorical face aftereffects
School, Centre or Institute School of Psychology
Institution The University of Queensland
Publication date 2011-10-12
Thesis type Honours Thesis
Supervisor Associate Professor Derek Arnold
Total pages 69
Language eng
Subjects 1701 Psychology
Abstract/Summary Exposure to a face can bias subsequent judgments of other faces. Looking at a sad face, for instance, can cause subsequent expressionless faces to be judged as happier than they would otherwise. It is thought that this happens because face recognition involves a norm-based opponent code, the mid-point of which shifts during prolonged exposure to a face. Here I explore an alternative possibility – that people tend to judge inputs relative to recently seen exemplars. Thus a neutral face might be judged as unlike the preceding sad face, and therefore as happy. This suggests that aftereffects could be induced between arbitrary categories. To test this, participants adapted to images of animals (cows or horses), fruit (apples or oranges), cutlery (knives or spoons) and to distinct classes of objects (rocks or cookies). In all cases repeated exposure to an unambiguous exemplar (e.g. a horse) resulted in a bias to report that test images (morphs between the two exemplars) looked more like the other exemplar (e.g. a cow). I also replicated effects thought to be characteristic of face adaptation with arbitrary non-face stimuli, namely size invariance, contingent adaptation, and the lack of an aftereffect after adapting to the average image. Animal aftereffects persisted when adapting and test images differed in size, ruling out an account based solely on low-level visual adaptation. Opposite fruit aftereffects could be induced simultaneously in different retinal locations, suggesting inputs tend to be judged relative to exemplars recently seen in the same location. Finally, adapting to an image at the boundary between two categories did not bias subsequent judgements. The data are consistent with the existence of a general contrast effect between successive images, rather than a face-specific opponent code.
Keyword Reinterpretation of categorical face aftereffects
Bias of exposure

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Created: Wed, 27 Jun 2012, 11:07:40 EST by Mrs Ann Lee on behalf of School of Psychology