Abstract: We describe a method for quantifying relative sociability within a group of animals, which is defined as the tendency to be close to others within the group and based on the identification of nearest neighbours. The method is suitable for groups of animals in which all individuals are visible and identifiable and has application as a tool in other areas of behavioural research. A sociability index (SI) is calculated, which is equivalent to the relative proportion of time that an individual spends as the nearest neighbour of other animals in the group and is scaled to have an expectation of 1.0 under the null hypothesis of random mixing. Associated pairs, which are animals seen as nearest neighbours more often than would be expected by chance, are also identified. The method tests for consistency across a number of independent observation periods, by comparison with values obtained from simulations in which animal identities are randomised between observation periods. An experiment is described in which 8 groups of 7 grazing sheep were each observed for a total of 10, one-hour periods and the identities and distances away of the 3 nearest neighbours of each focal animal recorded at 5-min intervals. Significant within-group differences in SIs were found in four of the groups (P < 0.001). SIs calculated using the nearest neighbour, two nearest neighbours or three nearest neighbours, were generally highly correlated within all groups, with little change in the ranking of animals. There were significant negative correlations between SIs and nearest neighbour distances in five of the groups. It was concluded that there was no advantage in recording more than one neighbour to calculate the SI. Advantages of the SI over other methods for measuring sociability and pair-wise associations are discussed.

Abstract: Neurobiological and behavioral research indicates that place learning and response learning occur simultaneously, in parallel. Such findings seem to conflict with theories of associative learning in which different cues compete for learning. The authors conducted place+response training on a radial maze and then tested place learning and response learning separately by reconfiguring the maze in various ways. Consistent with the effects of manipulating place and response systems in the brain (M. G. Packard & J. L. McGaugh, 1996), well-trained rats showed strong place learning and strong response learning. Three experiments using associative blocking paradigms indicated that prior response learning interferes with place learning. Blocking and related tests can be used to better understand how memory systems interact during learning.

Abstract: Although much is known about how some primates--in particular, monkeys and apes--represent and enumerate different numbers of objects, very little is known about the numerical abilities of prosimian primates. Here, we explore how four lemur species (Eulemur fulvus, E. mongoz, Lemur catta, and Varecia rubra) represent small numbers of objects. Specifically, we presented lemurs with three expectancy violation looking time experiments aimed at exploring their expectations about a simple 1+1 addition event. In these experiments, we presented subjects with displays in which two lemons were sequentially added behind an occluder and then measured subjects' duration of looking to expected and unexpected outcomes. In experiment 1, subjects looked reliably longer at an unexpected outcome of only one object than at an expected outcome of two objects. Similarly, subjects in experiment 2 looked reliably longer at an unexpected outcome of three objects than at an expected outcome of two objects. In experiment 3, subjects looked reliably longer at an unexpected outcome of one object twice the size of the original than at an expected outcome of two objects of the original size. These results suggest that some prosimian primates understand the outcome of simple arithmetic operations. These results are discussed in light of similar findings in human infants and other adult primates.

Abstract: Male mammals typically outperform their conspecific females on spatial tasks. A sex difference in cues used to solve the task could underlie this performance difference as spatial ability is reliant on appropriate cue use. Although comparative studies of memory in food-storing and non-storing birds have examined species differences in cue preference, few studies have investigated differences in cue use within a species. In this study, we used a one-trial associative food-finding task to test for sex differences in cue use in the great tit, Parus major. Birds were trained to locate a food reward hidden in a well covered by a coloured cloth. To determine whether the colour of the cloth or the location of the well was learned during training, the birds were presented with three wells in the test phase: one in the original location, but covered by a cloth of a novel colour, a second in a new location covered with the original cloth and a third in a new location covered by a differently coloured cloth. Both sexes preferentially visited the well in the training location rather than either alternative. As great tits prefer colour cues over spatial cues in one-trial associative conditioning tasks, cue preference appears to be related to the task type rather than being species dependent.