The influence of local enhancement on choice performances in African Grey parrots (Psittacus erithacus) and jackdaws (Corvus monedula).

Being attentive to the behavior of others may be advantageous to gain important information, for example, on the location of food. Often, this is achieved through simple local enhancement. However, this is not always beneficial, as it may override cognitive abilities, with negative consequences. Grey parrots (Psittacus erithacus) and ravens have already succeeded in exclusion tasks, but carrion crows do so only when controlling for local enhancement, and jackdaws (Corvus monedula) fail entirely. Presently, we tested whether jackdaws would still be influenced by local enhancement in a simple choice-task. We compared their performance with those of Grey parrots. Since these birds did not respond to enhancement in the exclusion task, we expected them also to be less susceptible to enhancement here. In our tasks, two pieces of food were visibly hidden under two cups. Then one cup was lifted, the reward was shown to the bird and was either laid back underneath the cup or was removed. Alternatively, both manipulations were combined with the first reward being shown to the bird and the second one being removed or vice versa. Surprisingly, both species had a preference for the last handled cup, irrespective of whether it contained food or not. However, if the birds had to wait for 10 seconds after the presentation, the jackdaws performed better than the Grey parrots. Additionally, the delay improved the performance of both species in conditions in which the reward was removed last and deteriorated their performance in conditions in which the item was shown last.