Effects of spatial food distribution on search behavior in rats (Rattus norvegicus)
To analyze how search strategies are adapted according to the geometric distribution of food sources, the authors submitted rats to a search task in which they had to explore 9 food trays in an open field and avoid visiting already-depleted trays. Trays were spatially arranged in 4 independent configurations: a cross, a 3 × 3 […]
Animal behaviour: cognitive bias and affective state.
Information processing by humans can be biased by their emotions — for example, anxious and depressed people tend to make negative judgements about events and to interpret ambiguous stimuli unfavourably1, 2, 3, 4. Here we show that such a ‘pessimistic’ response bias can also be measured in rats that are housed in unpredictable conditions5, 6. […]
Grey parrot (Psittacus erithacus) numerical abilities: Addition and further experiments on a zero-like concept
A Grey parrot (Psittacus erithacus), able to quantify 6 or fewer item sets (including heterogeneous subsets) by using English labels (I. M. Pepperberg, 1994), was tested on addition of quantities involving 0-6. He was, without explicit training, asked, “How many total X?” for 2 sequentially presented collections (e.g., of variously sized jelly beans or nuts) […]
A Gray Seal’s (Halichoerus grypus) Responses to Experimenter-Given Pointing and Directional Cues
A gray seal (Halichoerus grypus) was trained to touch a target on its left or right by responding to pointing signals. The authors then tested whether the seal would be able to generalize spontaneously to altered signals. It responded correctly to center pointing and head turning, center upper body turning, and off-center pointing but not […]
The effects of environmental control on cognition in rats (Rattus norvegicus)
The aim of this study was to allow nonhuman animals to control their environment using operant conditioning procedures and to assess the effect of control on cognitive tasks. The study tested 4 predictions: (a) rats (Rattus norvegicus) will control a light stimulus; (b) animals will exhibit preferences for particular stimulus strengths; (c) animals who exert […]