Visual Perception of a Motion Aftereffect in Domestic Chickens (Gallus gallus): A Behavioural Analytic Approach

Abstract

The motion aftereffect (MAE) is an illusory motion in the opposite direction after the sudden halt of a prolonged moving visual stimulus. The human experience of the motion aftereffect has been extensively researched utilising many different experimental approaches. The ability of the avian species to perceive this motion illusion has not been so well researched and such a phenomenon has never been investigated in domestic chickens. The aim of the experiment reported in this thesis was to test whether domestic chickens can perceive a motion aftereffect. Xiao and Gunturkun (2008) carried out a study to investigate whether pigeons could perceive the motion aftereffect. After initially failing to obtain evidence for the effect they modified their procedure and found results that were better but still not strongly suggestive of a robust motion aftereffect. Their methodology was further refined for this thesis to see if evidence for the motion aftereffect could be found in chickens. The chickens received initial discrimination training to differentiate between static, upward and downward moving grating patterns. Once they reached the criterion for this task reliably, each subject underwent test trials where they were exposed to a static pattern after prolonged presentation of a moving grating stimulus. Results from the choice behaviour of the chickens indicated they did not experience a motion aftereffect. This thesis and the previous study would suggest there is not a reliable motion aftereffect for birds. Whether this reflects limitations of the research design or the nature of the avian visual system is still to be determined.