Supplementary material from "Kea show no evidence of inequity aversion"

In support of this, evidence of inequity aversion in nonhuman animals has typically been found in species that, like humans, live in complex social groups and demonstrate cooperative behaviours. We examined inequity aversion in the kea ( Nestor notabilis ), which lives in social groups but does not appear to demonstrate wild cooperative behaviours, using a classic token exchange paradigm.

We compared the number of successful exchanges and the number of abandoned trials in each condition and found no evidence of an aversion to inequitable outcomes when there was a difference between reward quality or working effort required between actor and partner. We also found no evidence of inequity aversion when the subject received no reward while their partner received a low value reward.