In the field of stimulus generalization, an old yet unresolved discussion pertains to what extent stimulus misidentifications contribute to the pattern of conditioned responding. In this article, we perform cluster analysis on six datasets (four published datasets and two unpublished datasets, included N = 950) to examine the relationship between…

The quest for determining the degree of learning difficulty associated with different types of categories has been instrumental in our understanding of human categorization behavior and, more broadly, human generalization. For instance, we now know that the topological nature of the dimensions (e.g., whether these are integral or separable) that…

Several recent studies have explored what Michael (e.g., 1982) termed the "value-altering" effect and the "behavior-altering" effect of motivating operations. One aspect of the behavior-altering effect that has garnered no recent attention involves changes in stimulus control produced by motivating operations. To call attention to this aspect of…

In a temporal double bisection task, animals learn two discriminations. In the presence of Red and Green keys, responses to Red are reinforced after 1-s samples and responses to Green are reinforced after 4-s samples; in the presence of Blue and Yellow keys, responses to Blue are reinforced after 4-s samples and responses to Yellow are reinforced…

A shift in generalization gradients away from S+ and towards stimuli on the opposite end of the stimulus dimension from S- is a well established phenomenon in the laboratory, occurring with humans and nonhumans and with a wide range of stimuli. The phenomenon of gradient shifts has also been observed to have an analogous relationship to a variety…

According to the composite-stimulus control model (Weiss, 1969, 1972b), an individual discriminative stimulus (S[superscript D]) is composed of that S[superscript D]'s on-state plus the off-states of all other relevant S[superscript D]s. The present experiment investigated the reversibility of composite-stimulus control. Separate groups of rats…

In this article, the author discusses and presents seven possibilities that describe how symmetry principles are reflected in behavior analysis. First, if there are apparently no functional distinctions to be made between positive and negative reinforcement, then reinforcer effectiveness (by various measures) is invariant under a simple inversion…

Hearing-impaired 6- to 13-year-olds (N=24), trained to discriminate between two stimulus complexes differing in shape, direction, and number, were asked to discriminate between individual characteristics in all possible pair combinations. General failure to respond to all characteristics equally suggested that hearing-impaired children tend to be…

Children and adults were trained and tested on formation of novel simple discriminations and conditional stimulus relations. Subjects who formed these sets were trained and tested on formation of stimulus equivalence classes. A modest majority of children matched directly paired stimuli; a few matched indirectly paired stimuli. All normal adults…

Ten author-contributed papers present information on stimulus control research and developmental disabilities. Articles address such isues as the role of naming, development of stimulus classes, control by exclusion, and comparison of trial-and-error and graduated stimulus change procedures. (CL)

Tests the effects of stimulus variability on overgeneralization and overdiscrimination errors in children and adults. The subjects (n=64), adults and five-, seven-, and nine-year-old children, participated in a visual discrimination task. (CM)

Infants were tested for recognition and discrimination of expressions. Ten-month olds familiar with a mix of happy and surprised expressions demonstrated generalized discrimination of positive affect. Only after seven months does dependence on the presence of expression-specific features for affect recognition and discrimination diminish. (BC)

We have used a genetically tractable model system, the fruit fly "Drosophila melanogaster" to study the interdependence between sensory processing and associative processing on learning performance. We investigated the influence of variations in the physical and predictive properties of color stimuli in several different operant-conditioning…

Trained preschoolers and adults on three sets of successive discriminations with stimuli labeled A, B, and R. Tested for derived stimulus-response relations and stimulus-stimulus relations. Adults displayed class-consistent B-R and A-B performances over all conditions. Children's display of class-consistent B-R performance varied by training…

Stimulus discrimination is a standard subject in undergraduate courses presenting basic principles of learning, and a particularly interesting aspect of discrimination is the peak shift phenomenon. Peak shift occurs in generalization tests following intradimensional discrimination training as a displacement of peak responding away from the S+ (a…