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Frank H. Durgin, Zhi Li; Why do things seem closer than they are?. Journal of Vision 2013;13(9):1392. doi: 10.1167/13.9.1392.
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© ARVO (1962-2015); The Authors (2016-present)
Systematic and stable biases in the visual appearance of locomotor space may reflect functional coding strategies for the sake of more precisely guiding motor actions. Perceptual matching tasks and verbal estimates suggest that there is a systematic underestimation of egocentric distance along the ground plane in extended environments. Whereas underestimation has previously been understood as a mere failure of proper verbal calibration, such an interpretation cannot account for perceptual matching results. Moreover, we have observed that the subjective geometry of distance perception on the ground plane is quantitatively consistent with the explicit overestimation of angular gaze declination which we have measured independently of perceived distance. We suggest that there is a locally-consistent expansion of specific angular variables in visual experience that is useful for action, and that this stable expansion may aid action by retaining more precise angular information, despite the information being mis-scaled approximately linearly. Actions are effective in this distorted perceived space by being calibrated to their perceived consequences (but notice that this means that measuring spatial action parameters, such as walked distance, are not directly informative about perceived distance). We distinguish our view from reports of small judgmental biases moderated by semantic, social and emotional factors on the one hand (which might or might not involve changes in visual appearance) and also from the prevailing implicit assumption that the perceptual variables guiding action must be accurate. The perceptual variables guiding action must be stable in order to support action calibration and precise to support precise action. We suggest that the systematic biases evident in the visual (and haptic) phenomenology of locomotor space may reflect a functional coding strategy that can render actions that are coded in the same perceived space more effective than if space were perceived veridically.
Meeting abstract presented at VSS 2013
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