Reinforcement strength in classical conditioning of leg flexion,freezing, and heart rate in cats

Stable leg-flexion CRs were successfully elaborated in cats receiving tone-strong shock pairings, but not in cats receiving tone-weak shock pairings. Both shock USs elicited reliable flexion URs in the presence of the CS, thus satisfying the contiguity requirement basic to the Pavlovian paradigm. Elaboration of the flexion CRs required a large number of trials relative to the conditioned freezing and decelerative heart rate responses which appeared after only a very few trials in the strong-US cats. As with flexion CRs, freezing and heart-rate responses never developed with the weak-shock US. When the weak-US cats were later switched to the strong US, freezing and heart-rate CRs quickly appeared and flexion CRs appeared after fewer strong-US trials than in cats receiving the strong shock originally. The results were interpreted as supporting a reinforcement conception of classical defense conditioning and as indicating the importance of using a US capable of eliciting emotional responses.     

Stimulus correlates of tachistoscopic discrimination-recognition performance: Compactness,jaggedness, and areal asymmetry

The utility of three physical dimensions (compactness, jaggedness, and areal asymmetry) of four-sided random forms on discrimination-recognition performance was examined. Six experimental conditions were defined by constructing discrimination-recognition problems wherein forms were paired on the basis of a high or low value on each of the three physical dimensions. Twenty-six Ss were randomly assigned to each experimental condition and were tested on five problems, four times at each of five single form duration times. Each problem presentation consisted of selecting which of two forms had been previously exposed at the selected duration. Analyses of the number of correct responses indicated support for the existence of a selective attention process and the utility of the compactness physical dimension.     

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