Perceptual learning in maze discriminations

In Experiment 1, rats were trained on a discrimination between rubber- and sandpaper-covered arms of a maze after one group had been pre-exposed to these intra-maze cues. Pre-exposure facilitated subsequent discrimination learning, unless the discrimination was made easier by adding further discriminative stimuli, when it now significantly retarded learning. In Experiment 2, rats were trained on an extra-maze spatial discrimination, again after one group, but not another, had been pre-exposed to the extra-maze landmarks. Here too, pre-exposure facilitated subsequent discrimination learning, unless the discrimination was made substantially easier by arranging that the two arms between which rats had to choose were always separated by 135°. The results of both experiments can be explained by supposing that perceptual learning depends on the presence of features common to S+ and S-.     

Attitudes and Attraction: Optimism and Weight as Explanations for the Similarity–Dissimilarity Asymmetry

The positive link between attitude similarity and attraction is one of the fundamental outcomes in social psychology. However, attitude dissimilarity seems to be a stronger driver of this relationship than attitude similarity. The authors review the evidence on this similarity–dissimilarity asymmetry, and discuss two explanations. One is that people generally enter into interactions with optimism, and so supposedly neutral partners are often seen as mildly positive. Another is that dissimilar attitudes carry greater weight than similar attitudes in cognitive processes. Implications of these mechanisms for wider issues in person perception and attitude structure are discussed, connecting them with more recent theories of attitudinal ambivalence and evaluative space.