Search asymmetry for expansion and contraction motion in pigeons(Summary of Awarded Presentation at the 30th Annual Meeting)

抄録

We examined whether pigeons demonstrated a search asymmetry between expansion and contraction targets, using a rotating logarithmic spiral pattern that induces illusory expansion and contraction in humans without changes in the pattern's physical size. Four pigeons were arbitrarily divided into two groups. Two pigeons in the Target-Expansion Group were trained to search for 1 expanding spiral (target) among 5 contracting ones (distractors) in displays comprising a total of 6 spirals (display size=6). Two pigeons in the Target-Contraction Group were trained to search for 1 contracting spiral among 5 expanding ones. Pigeons successfully learned to search for the target and they were later tested with display sizes of 3, 6, 9, and 12. The pigeons in the Target-Expansion Group showed higher search accuracy scores and shorter reaction times than the pigeons in the Target-Contraction Group. The pigeons thus demonstrated a search asymmetry between expansion and contraction targets as shown in previous studies in humans. We discuss the results in relation to optic flow.