Goffin's cockatoos discriminate objects based on weight alone

Abstract

Paying attention to weight is important when deciding upon an object's efficacy or value in various contexts (e.g. tool use, foraging). Proprioceptive discrimination learning, with objects that differ only in weight, has so far been investigated almost exclusively in primate species. Here, we show that while Goffin's cockatoos learn faster when additional colour cues are used, they can also quickly learn to discriminate between objects on the basis of their weight alone. Ultimately, the birds learned to discriminate between visually identical objects on the basis of weight much faster than primates, although methodological differences between tasks should be considered.

Recent developments in parrot cognition: a quadrennial update

“…In a previous experiment investigating how information is acquired during object exploration, kea were able to distinguish between objects of a certain weight when paired with a distinct color but not with a possibly less salient feature of patterns (M. L. Lambert et al 2017 ). In an effort to study weight discrimination in Goffin´s cockatoos, P. J. Lambert et al ( 2021 ) provided them with a discrimination task. Half of the birds had to choose one of two balls that differed in both weight and color while the other half were provided only with weight information (the balls were otherwise identical).…”

“…In comparison to chimpanzees (Povinelli 2011 ), Goffin’s required strikingly fewer trials to differentiate between identical objects of different weights. Whether this was due to slight—but possibly important—differences in methodology or different ecological importance of attending to an object´s weight demands further investigation (P. J. Lambert et al 2021 ).…”

“…However, the species recently tested in the condition with crossed strings, failed, which is in line with most – but not all – previously tested species. Studies on the use of object properties and physical entities show for example that some parrots form mental templates of some object properties (Laumer et al 2021a ), are sensitive to liquid overconservation (Cornero et al 2020 ), discriminate based on weight (P. J. Lambert et al 2021 ), and may perceive the virtual and real world as a continuum (Bastos et al 2021c ). Tool use studies in recent years included new coincidental observations that were further thoroughly examined (O’Hara and Mioduszewska et al 2021 ; Bastos et al 2021a ).…”