Stimulus generalization and operant discrimination as a function of level of motivation ...

The primary purpose of this experiment was to investigate the relationship between the level of primary motivation (hunger) and two basic phenomena of behavior, stimulus generalization and discrimination learning. The difficulty of the discrimination was also systematically varied so that intersection effects involving problem difficulty might be observed and utilized in the analysis of the main behavioral processes under scrutiny. An additional problem which was investigated was that of the effect of discrimination training on a subsequently obtained generalization gradient. Procedures were employed which made possible a separation of the effects of the physical difference between stimuli to be discriminated and the amount of discrimination training administered, on properties of the post-discrimination generalization gradient. A final problem with which we were concerned was that of the relationship between stimulus generalization and the ease of formation of a subsequently learned discrimination. A number of different measures of discrimination learning were used and different aspects of previously obtained generalization gradients were utilized in an attempt to predict them. The character of the present study was essentially empirical, but the data will also be examined for their bearing upon a set of important basic issues in learning theory which extend beyond those functional relationships which determined the experimental design.