Memory for what, where, when and who in nonhuman animals

Can birds remember who watched them do what, as well as when and where?

Scrub jays have already been demonstrated to encode the “what-where-when” (what happened, where it happened and when it happened) of specific caching episodes (Clayton, N.S. & Dickenson, A., 1998). It has even been shown that scrub jays, when observed caching food, re-cache food only if they have stolen the food of another bird in the past (Emery & Clayton, 2001). This finding suggests that jays who have stolen food in the past can also anticipate their own food being stolen in the future, and, therefore, take precautionary measures to reduce this possibility.

Now, the results of a recent study by Dally et al. (2006) suggest that scrub jays also remember who was present during earlier caching events. In this study, jays were more likely to re-cache food if a more dominant bird observed them caching than if a less dominant bird did so. As Dally et al. note, since scrub-jays can only defend their caches against subordinates, it seems very likely that the observed re-caching behaviour is advantageous in situations where the jays are caching in view of dominant birds, as it is thought to reduce the likelihood of future pilfering.

The authors of this clever study point out that the re-caching behaviour demonstrated by their jays is not necessarily based on humanlike episodic memory, as mental reconstruction of the past is not required for one to possess “what-where-when” memories. The authors also point out that the jays’ ability to keep track of who was watching when does not require a humanlike “theory-of-mind”. Instead, it may result from reasoning about future risk or behavioral predispositions in combination with specific learning algorithms. Nonetheless, the results of this study suggest that nonhuman animals might discriminate between individuals with different knowledge states.

Food-Caching Western Scrub-Jays Keep Track of Who Was Watching When
Dally, J. M., Emery, N. J., Clayton, N. S.
Science. 2006; 312(5780): 1662-1665

Western scrub-jays (Aphelocoma californica) hide food caches for future consumption, steal others’ caches, and engage in tactics to minimize the chance that their own caches will be stolen. We show that scrub-jays remember which individual watched them during particular caching events and alter their recaching behavior accordingly. We found no evidence to suggest that a storer’s use of cache protection tactics is cued by the observer’s behavior.