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.

Keywords: discrimination learning; parrot cognition; physical cognition; weight discrimination.

Figure 1.

The order (1 to 5) of object placement (1 and 2 by the experimenter, 3 to 5 by the subject) in a trial. Arrows show the object movement by the subject. Distances are indicated by the dotted lines and recorded in cm.

Figure 2.

Influence of the experimental group on probability of success, for (a) the Pre-experience group in the colour-weight task and Test-only group in the weight-only task (until criterion) and (b) both groups in all their sessions of the weight-only task.