Kea (Nestor notabilis) fail a loose-string connectivity task

Amalia P M Bastos,Patrick M Wood,Alex H Taylor

doi:10.1038/s41598-021-94879-x

Abstract

Naïve individuals of some bird species can rapidly solve vertical string-pulling tasks with virtually no errors. This has led to various hypotheses being proposed which suggest that birds mentally simulate the effects of their actions on strings. A competing embodied cognition hypothesis proposes that this behaviour is instead modulated by perceptual-motor feedback loops, where feedback of the reward moving closer acts as an internal motivator for functional behaviours, such as pull-stepping. To date, the kea parrot has produced some of the best performances of any bird species at string-pulling tasks. Here, we tested the predictions of the four leading hypotheses for the cognition underpinning bird string-pulling by presenting kea with a horizontal connectivity task where only one of two loose strings was connected to the reward, both before and after receiving perceptual-motor feedback experience. We find that kea fail the connectivity task both before and after perceptual-motor feedback experience, suggesting not only that kea do not mentally simulate their string-pulling actions, but also that perceptual-motor feedback alone is insufficient in eliciting successful performance in the horizontal connectivity task. This suggests a more complex interplay of cognitive factors underlies this iconic example of animal problem-solving.

Highlights

Naïve individuals of some bird species can rapidly solve vertical string-pulling tasks with virtually no errors
Our study tested whether experience of a perceptual-motor feedback loop during string-pulling might explain the pattern of results observable in the bird literature: naïve subjects fail at loose-string connectivity t asks[5], and experienced birds sometimes succeed at it8–14
Kea failed this task both before and after receiving experience of vertical string-pulling, that is, regardless of their experience with perceptual-motor feedback loops. This result both opposes the predictions of the insight, planning, and means-end understanding hypotheses which predict an immediate understanding of string-pulling problems without perceptual-motor feedback experience, and shows that feedback experience alone cannot elicit success at the horizontal loose-string connectivity task

Summary

Introduction

Naïve individuals of some bird species can rapidly solve vertical string-pulling tasks with virtually no errors. The swiftness and efficiency of this behaviour in naïve individuals has been attributed by different researchers as evidence for various cognitive mechanisms including planning, means-end understanding, and insight (an immediate understanding of the problem without prior experience)[1,2,3] All three of these hypotheses would predict that, upon seeing a string with a reward at one end, subjects can mentally simulate the effects of their pulling actions on the string, imagining how they might move the reward closer to themselves. Groups of individuals that were either naïve to or experienced with vertical string-pulling were presented with a string-pulling task that required a counter-intuitive motor action: subjects had to pull down on a string looping over a higher perch before coming back down

Methods

Results

Conclusion