The Role of Background Statistics in Face Adaptation.
The Journal of Neuroscience
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Cross-adaptation is widely used to probe whether different stimuli share common neural mechanisms. For example, that adaptation to second-order stimuli usually produces little aftereffect on first-order stimuli has been interpreted as reflecting their separate processing. However, such results appear to contradict the cue-invariant responses of many visual cells. We tested the novel hypothesis that the null aftereffect arises from the large difference in the backgrounds of first- and second-order stimuli. We created second-order faces with happy and sad facial expressions specified solely by local directions of moving random dots on a static-dot background, without any luminance-defined form cues. As expected, adaptation to such a second-order face did not produce a facial-expression aftereffect on the first-order faces. However, consistent with our hypothesis, simply adding static random dots to the first-order faces to render their backgrounds more similar to that of the adapting motion face led to a significant aftereffect. This background similarity effect also occurred between different types of first-order stimuli: real-face adaptation transferred to cartoon faces only when noise with correlation statistics of real faces or natural images was added to the cartoon faces. These findings suggest the following: (1) statistical similarities between the featureless backgrounds of the adapting and test stimuli can influence aftereffects, as in contingent adaptation; (2) weak or null cross-adaptation aftereffects should be interpreted with caution; and (3) luminance- and motion-direction-defined forms, and local features and global statistics, converge in the representation of faces.
|Title:||The Role of Background Statistics in Face Adaptation|
|Open access status:||An open access version is available from UCL Discovery|
|Additional information:||Copyright of all material published in The Journal of Neuroscience remains with the authors. The authors grant the Society for Neuroscience an exclusive license to publish their work for the first 6 months. After 6 months the work becomes available to the public to copy, distribute, or display under a Creative Commons Attribution 4.0 International (CC BY 4.0) license (https://creativecommons.org/licenses/by/4.0/).|
|Keywords:||human visual-system, information-transmission, 2nd-order motion, image statistics, natural images, facial motion, cortex, 1st-order, psychophysics, recognition|
|UCL classification:||UCL > School of Life and Medical Sciences
UCL > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > School of Life and Medical Sciences > Faculty of Life Sciences > Gatsby Computational Neuroscience Unit
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