Abstract: We examined how the brain organizes interrelated facts during learning and how the facts are subsequently manipulated in a transitive inference (TI) paradigm (e.g., if A<B and B<C, then A<C). This task determined features such as learned facts and behavioral goals, but the learned facts could be organized in any of several ways. For example, if one learns a list by operating on paired items, the pairs may be stored individually as separate facts and reaction time (RT) should decrease with learning. Alternatively, the pairs may be stored as a single, unified list, which may yield a different RT pattern. We characterized RT patterns that occurred as participants learned, by trial and error, the predetermined order of 11 shapes. The task goal was to choose the shape occurring closer to the end of the list, and feedback about correctness was provided during this phase. RT increased even as its variance decreased during learning, suggesting that the learnt knowledge became progressively unified into a single representation, requiring more time to manipulate as participants acquired relational knowledge. After learning, non-adjacent (NA) list items were presented to examine how participants reasoned in a TI task. The task goal also required choosing from each presented pair the item occurring closer to the list end, but without feedback. Participants could solve the TI problems by applying formal logic to the previously learnt pairs of adjacent items; alternatively, they could manipulate a single, unified representation of the list. Shorter RT occurred for NA pairs having more intervening items, supporting the hypothesis that humans employ unified mental representations during TI. The response pattern does not support mental logic solutions of applying inference rules sequentially, which would predict longer RT with more intervening items. We conclude that the brain organizes information in such a way that reflects the relations among the items, even if the facts were learned in an arbitrary order, and that this representation is subsequently used to make inferences.

Abstract: Learning is likely to be costly and thus subject to trade-off with other components of life history. An obvious prediction, therefore, is that investment in learning, and thus learning performance, will vary with individual life history strategy and the reproductive value of the learning outcome. We tested this idea in the context of social dominance in male laboratory mice, using a simple radial maze paradigm to compare the ability of high- and low-ranking male mice to track changing food location. We tested animals in randomly selected pairs before and after establishing aggressive rank relationships to distinguish intrinsic differences in learning ability from those attributable to acquiring high or low rank. There was no difference in learning between later dominants and subordinates prior to establishing rank relationships. After pairing, however, dominants showed a significantly greater percentage of correct responses, with the difference being greatest earlier in a sequence of trials. The percentage of correct responses also increased with the amount of aggression initiated during pairing. The results thus appeared to reflect a state-dependent change in learning associated with the aggressive social relationships formed during pairing.

Abstract: Two-action tests of imitation compare groups that observe topographically different responses to a common manipulandum. The general aim of the two experiments reported here was to find a demonstrator-consistent responding effect in a procedure that could be elaborated to investigate aspects of what was learned about the demonstrated lever response. Experiment 1 was a pilot study with rats of a variant of the two-action method of investigating social learning about observed responses. Groups of observer rats ( Rattus norvegicus) saw a demonstrator push a lever up or down for a food reward. When these observers were subsequently given access to the lever and rewarded for responses in both directions, their directional preferences were compared with two 'screen control' groups that were unable to see their demonstrators' behaviour. Demonstrator-consistent responding was found to be restricted to observers that were able to see demonstrator performance, suggesting that scent cues alone were insufficient to cue a preference for the demonstrators' response direction and thereby that the rats learned by observation about body movements (imitation) or lever movement (emulation). Experiment 2 assessed responding on two levers, one that had been manipulated by the demonstrator, and a second, transposed lever positioned some distance away. Demonstrator-consistent responding was abolished when actions were observed and performed in different parts of the apparatus, suggesting that observed movement was encoded allocentrically with respect to the apparatus rather than egocentrically with respect to the actor's body. With particular reference to the influence of scent cues, the results are discussed in relation to the strengths and weaknesses of this and other varieties of the two-action procedure as tests of imitation in animals and human infants.

Abstract: Studies of imitation in animals have become numerous in recent times, but do they contribute to a comparative psychology of social learning? We review this burgeoning field to identify the problems and prospects for such a goal. Difficulties of two main kinds are identified. First, researchers have tackled questions about social learning from at least three very different theoretical perspectives, the “phylogenetic”, “animal model”, and “adaptational”. We examine the conflicts between them and consider the scope for integration. A second difficulty arises in the methodological approaches used in the discipline. In relation to one of these – survey reviews of published studies – we tabulate and compare the contrasting conclusions of nine articles that together review 36 studies. The basis for authors' disagreements, including the matters of perceptual opacity, novelty, sequential structure, and goal representation, are examined. In relation to the other key method, comparative experimentation, we identify 12 studies that have explicitly compared species' imitative ability on similar tasks. We examine the principal problems of comparing like with like in these studies and consider solutions, the most powerful of which we propose to be the use of a systematic range of task designs, rather than any single “gold standard” task.

Abstract: Despite the long divergent evolutionary history of birds and mammals, early avian and primate cognitive development have many convergent features. Some of these features were investigated with a series of tasks designed to assess human infant development. The tasks were presented to young parakeets to assess their means-end problem solving abilities. Examples of these early skills are: attaining and playing with objects, retrieving rewards through use of a stick or rake, or by pulling in rewards on supports or on the ends of strings. Twelve such tasks were presented to 11 young yellow-crowned parakeets ( Cyanoramphus auriceps) to investigate their natural abilities; there was no attempt to train them to do those tasks that they did not spontaneously perform. Six of the birds were parent-raised and five were hand-raised. The birds completed 9 of the 12 tasks, demonstrating all the Piagetian sensorimotor circular reactions, but they failed to hand-watch (“claw-watch”), to stack objects, or to fill a container. Their ordinality on the tasks differed from that of human infants in that locomotion to obtain objects occurred earlier in the avian sequence of development and the mid-level tasks were performed by the two groups of avian subjects in a mixed order perhaps indicating that these abilities may not emerge in any particular order for these birds as they supposedly do for human infants. The hand-raised group needed fewer sessions to complete these means-end tasks.