Abstract: When animals learn a simultaneous discrimination, some of the value of the positive stimulus (S+) appears to transfer to the negative stimulus (S-). The present experiments demonstrate that such value transfer can also be found in humans. In Experiment 1 humans were trained on 2 simple simultaneous discriminations, the first between a highly positive stimulus, A (1,000 points); and a negative stimulus, B (0 points); and the second between a less positive stimulus, C (100 points); and a negative stimulus, D (0 points). On test trials, most participants preferred B over D. In Experiments 2 and 3 the value of the 2 original discriminations was equated in training (A[100]B[0] and C[100]D[0]). In Experiment 2 the values of the positive stimuli were then altered (A[1,000]C[0]); again, most participants preferred B over D. In Experiment 3, however, when the values of B and D were altered (B[1,000]D[0]), participants were indifferent to A and C. Thus, the mechanism that underlies value transfer in humans appears to be related to Pavlovian second-order conditioning. Similar mechanisms may be involved in assimilation processes in social contexts.

Abstract: When pigeons acquire a simple simultaneous discrimination, some of the value acquired by the S+ transfers to the S-. The mechanism underlying this transfer of value was examined in three experiments. In Experiment 1, pigeons trained on two simultaneous discriminations (A + B- and C +/- D-) showed a preference for B over D. This preference was reduced, however, following the devaluation of A. In Experiment 2, when after the same original training, value was given to D, the pigeons' preference for C did not significantly increase. In Experiment 3, when both discriminations involved partial reinforcement (S +/-), A + C- training resulted in a preference for B over D, whereas B + D- training resulted in a preference for A over C. Thus, simultaneous discrimination training appears to result in bidirectional within-event conditioning involving the S+ and S-.

Abstract: Directed-forgetting research with animals suggests that animals show disrupted test performance only under certain conditions. Important variables are (a) whether during training, the cue to forget (F cue) signals nonreward (i.e., that the trial is over) versus reward (i.e., that reinforcement can be obtained) and (b) given that reinforcement can be obtained on F-cue trials, whether the post-F-cue response pattern is compatible with the baseline memory task. It is proposed that some findings of directed forgetting can be attributed to trained response biases, whereas others may be attributable perhaps to frustration-produced interference. It is suggested that directed forgetting in animals should be studied using procedures similar to those used to study directed forgetting in humans. This can be accomplished by presenting, within a trial, both to-be-remembered and to-be-forgotten material.

Abstract: Baboons' (Papio cynocephalus ursinus) understanding of cause-effect relations in the context of social interactions was examined through use of a playback experiment. Under natural conditions, dominant female baboons often grunt to more subordinate mothers when interacting with their infants. Mothers occasionally respond to these grunts by uttering submissive fear barks. Subjects were played causally inconsistent call sequences in which a lower ranking female apparently grunted to a higher ranking female, and the higher ranking female apparently responded with fear barks. As a control, subjects heard a sequence made causally consistent by the inclusion of grunts from a 3rd female that was dominant to both of the others. Subjects responded significantly more strongly to the causally inconsistent sequences, suggesting that they recognized the factors that cause 1 individual to give submissive vocalizations to another.

Abstract: Six experiments using habituation of exploratory behavior tested whether disoriented rats foraging in a large arena encode the shapes of arrays of objects. Rats did not respond to changes in position of a single object, but they responded to a change in object color and to a change in position of 1 object in a square array, as in previous research (e.g., C. Thinus-Blanc et al., 1987). Rats also responded to an expansion of a square array, suggesting that they encoded sets of interobject distances rather than overall shape. In Experiments 4-6, rats did not respond to changes in sense of a triangular array that maintained interobject distances and angles. Shapes of object arrays are encoded differently from shapes of enclosures.