PhD ceremony Ms. E.E. van der Vaart: A cognitive model of caching by corvids

PhD ceremony: Ms. E.E. van der Vaart, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: A cognitive model of caching by corvids

Promotor(s): prof. C.K. Hemelrijk, prof. R. Verbrugge

Faculty: Mathematics and Natural Sciences

Corvids, the extended family of crows, have surprisingly large brains, and display all kinds of remarkable behavior. One species makes tools; another recognizes itself in the mirror. In addition, these birds are often considered to be capable of complex social reasoning. But the question remains if this behavior is as smart as it looks? In her investigation Elske van der Vaart used a new technique: Namely, that of computational cognitive modeling. This is an approach that is frequently used to study humans, but is rarely applied to other species.

It has been speculated that Western scrub jays, in particular, may possess a ‘theory of mind’, or the ability to reason about the mental states of others.

This view is the result of behavior that the birds display in the context of caching; when they hide food under the ground, saving it for later, they seem to flexibly respond to the threat of future theft. In particular, they tend to re-cache their items later if other birds saw where they were hidden, as if they can reason about what other birds can see.

Vander Vaart has built a kind of ‘virtual bird’, based on a number of basic assumptions about corvid memory and learning. Then this virtual bird is exposed to simulated versions of real experiments, in order to derive new explanations for why corvids re-cache the way they do. She concludes that in particular, it is shown that many experimental results can be explained in a cognitively less complex way than is currently done, and it is therefore too early to conclude that corvids possess a ‘theory of mind’.

Read also the press release Hiding behaviour of the scrub jay: more stress than smarts?