Do Dogs Demonstrate Susceptibility to a Vertically Presented Ponzo Illusion?

Sarah-Elizabeth Byosiere,Joyce Wuister,Lynna C Feng,Philippe A Chouinard

doi:10.26451/abc.05.03.01.2018

Abstract

Do Dogs Demonstrate Susceptibility to a Vertically Presented Ponzo Illusion?

Highlights

One way to uncover visual capabilities in animals is to assess perception of geometric illusions
All dogs performed above chance when discriminating between circles that differed in diameter by 20% (42 pixels, approximately 12.6 mm; group average: 78%, p < .001) or larger (Figure 5)
The model for the logistic regression was statistically significant when controlling for percent size difference nested within dog, Wald χ2 (8, N = 60) = 359.26, p < .001, indicating a significant relationship between performance and the percent size difference of the stimuli

Summary

Introduction

One way to uncover visual capabilities in animals is to assess perception of geometric illusions. One way to begin to uncover how animals see the world is to assess their misperception of geometric illusions, in which mechanisms that are normally helpful for accurately perceiving the environment trick the brain into applying ‘corrections’ to visual information in contexts where a correction is unnecessary While this sounds straightforward, in practice there is often variation in illusion susceptibility across species (for a review see Feng, Chouinard, Howell, & Bennett, 2017), including birds, fish, and primates. We assessed whether dogs demonstrate susceptibility to the Ponzo illusion (Byosiere, Feng, Rutter et al, 2017) (Figure 1, images 4 6) This illusion typically consists of two sized targets (e.g., circles or lines) that appear unequal when superimposed over converging lines that can be presented in a variety of contexts. One potential explanation for our previous findings is that the horizontally presented stimuli may not have induced the Ponzo illusion in dogs due to the fact that the illusory effect may have been weaker – it should be noted that it did not appear weak to the human researchers

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Results

Conclusion