Robust representation of shape in a Grey parrot (Psittacus erithacus)

Abstract

A Grey parrot, Griffin (Psittacus erithacus), previously taught English labels for various colors and shapes with respect to three-dimensional (3D) stimuli, was tested on his ability to transfer to very different two-dimensional (2D) images consisting of modal and amodal completion stimuli. For modal completion (aka subjective contours), Kanizsa figures were constructed using black 'pac-men' to form regular polygons on colored paper. For amodal completion, portions of variously colored regular 2D polygons were occluded by black circles or other black figures. For each task, Griffin provided a vocal English shape label for five possible shapes designated by their vertices (one, two, three, four, six). His accuracy was high for both amodal completed figures, including probe stimuli (28/38 correct) and modally completed figures (29/38 correct), with chance=0.20. The modally completed case (i.e., Kanizsa subjective figures) is of particular importance as there are no shared image parts between training and testing stimuli. We draw several conclusions from these results. First, a surface level completion process is fully operative insofar as Griffin was able to correctly identify shapes that differed considerably from training images. Second, because parrots can generalize from shapes of real objects to drawings where original image contours were clearly absent, the data provide a compelling example of shape invariance, indicating that visual shapes are processed far beyond that of their image description. Third, parrots with a repertoire of multiple vocal responses can be rigorously tested for visual competencies, an option as yet to be tried in other experimental animals.

Logical reasoning by a Grey parrot? A case study of the disjunctive syllogism

“…As had been the case in other studies with Griffin (e.g., Pepperberg & Nakayama, 2016) and another Grey parrot, Alex (e.g., Pepperberg & Carey, 2012), Griffin occasionally engaged in noncompliant behaviour. These instances were considered mistrials and were not included in our data set.…”

“…However, not only might Griffin's training regime exercise and develop executive function, it also might specifically exercise and develop the logical capacities at issue in these studies. Griffin experiences very few trials tapping any probed construct in any one day (e.g., Pepperberg & Nakayama, 2016), and so he is never rewarded for adopting a strategy that yields "enough" rewards. Rather, he must provide a single answer, and there is a high premium on figuring out a strategy that is certain to succeed in any given context.…”

The 24/7 approach to promoting optimal welfare for captive wild animals

“…Indeed, many animals are trained to cooperate with research (e.g. hydro-dynamic trail following in seals: Dehnhardt et al, 2001; underwater visual acuity in manatees: Bauer et al, 2003; shape representation in a grey parrot: Pepperberg and Nakayama, 2016). Animals are increasingly being tested individually in purpose-built research centres within zoos (e.g.…”

The Comparative Psychology of Intelligence: Some Thirty Years Later

“…However, I now am not entirely sure about a corollary of those two claimsthat acquisition of symbolic representation does not affect how subjects manipulate information-I believe that, in some specific instances, such a change in processing ability may exist. Possibly, once a non-human understands that a symbol can be used to represent an object or an action, it can then understand how, for example, a three-dimensional entity can be represented by a two-dimensional one (e.g., optical illusions, Pepperberg and Nakayama, 2016) or that two symbols (e.g., one vocal and one visual) that separately represent the same object can then represent each other (a formal equivalence, Pepperberg, 2006b), or that symbols can be used as place-markers to assist in tasks requiring memory and evaluation of probability (Pepperberg and Pailian, 2017;Clements et al, 2018). I will discuss one such topic-various studies on numerical concepts-in depth.…”