Physio-behavioural manifestations of ‘surprise’ in two parrot species: kea ( <i>Nestor notabilis</i> ) and Goffin’s cockatoos ( <i>Cacatua goffiniana</i> )

Abstract How animals react to violations of expectations offers a valuable lens into their perception of the world. Kea (Nestor notabilis) and Goffin’s cockatoos (Cacatua goffiniana) are optimal animal models to examine susceptibility to violations of expectations owing to their sophisticated physical exploration and cognition skills. This study involved a bait-and-switch of food items varying in desirability, followed by an information-seeking phase to examine not only violation susceptibility but also surprise behaviours expressed overtly and covertly in both positive and negative violation directions. We found that the kea, and not the cockatoos, exhibited susceptibility to the violation via likelihood to explore the violating stimulus. Furthermore, while this project serves, to our knowledge, as the first cognitive study using infrared thermography in fully unrestrained avian subjects, no conclusive results can be reported as to the effect of violations of expectation on subjects’ periorbital temperature, and thus physiological response. Implications for this research include novel perspectives into studying overt and covert responses following violated expectations, as well as expressions of information seeking in non-human species.