Functional classes and equivalence relations

Three adult subjects were taught a set of two-choice simultaneous discriminations, with three positive and three negative stimuli; all possible combinations of positive and negative stimuli yielded nine different pairs. The discriminations were repeatedly reversed and rereversed, the former positive stimuli becoming negative and the former negative stimuli becoming positive. With all subjects, a reversal of the contingencies for one pair of stimuli became sufficient to change their responses to all of the other pairs. The reversals had produced functional stimulus classes. Then, all subjects showed conditional discriminations emerging between members of a functional class; given a sample from one class and comparisons from both classes, they selected the comparison that was in the same class as the sample. Next, 2 of the subjects showed that the within-class conditional relations possessed the symmetric and transitive properties of equivalence relations; after having been taught to relate new stimuli to existing class members, the subjects then matched other class members to the new stimuli. Subsequent tests of two-choice discriminations showed that the conditional discriminations had transferred functional class membership to the new stimuli. The 3rd subject, who did not show equivalence relations among functional class members, was also found to have lost the within-class conditional relations after the equivalence tests.     

Second-order conditioning of the rabbit's nictitating membrane response. Interstimulus interval and frequency of CS-CS pairings.

Second-order conditioning of the rabbit's nictitating membrane response (NMR) was investigated when second-order trials (CS1-CS2) were intermixed with first-order trials (CS2-US) from the outset of training. Experiment 1 showed that CR acquisition to CS1 was inversely related to the CS1-CS2 interval but nevertheless extended to an interval of 8,400 ms. Experiment 2 revealed that CR acquisition of CS1 was an inverted-U function of the number of CS1-CS2 trials relative to a fixed number of CS2-US trials. Experiment 3 directly contrasted second-order conditioning with a reinforced serial compound procedure (CS1-CS2-US) and a mixed procedure in which second-order trials were intermixed with the reinforced serial compound. Second-order conditioning was about half the strength of either the reinforced serial compound or the mixed procedure, which were similar. The present results are discussed with respect to the relative strength of excitatory and inhibitory processes in second-order conditioning.     

Conditional withholding of proboscis extension in honeybees (Apis mellifera) during discriminative punishment.

Proboscis extension conditioning of honeybee workers was used to test the ability of bees to respond to appetitive and aversive stimuli while restrained in a harness that allows subjects to move their antennae and mouthparts (Kuwabara, 1957; Menzel, Erber, & Masuhr, 1974). Subjects were conditioned to discriminate between two odors, one associated with sucrose feeding and the other associated with a 10 V AC shock if they responded to the sucrose unconditioned stimulus (US) in the context of that odor. Most Ss readily learned to respond to the odor followed by sucrose feeding and not to the odor associated with sucrose stimulation plus shock. Furthermore, in the context of the odor associated with shock, significantly more subjects withheld or delayed proboscis extension on stimulation with the sucrose US than they did in the context of the odor associated with feeding. Thus, restrained honeybees can readily learn to avoid shock according to an odor context by withholding proboscis extension to a normally powerful releaser. Analysis of individual learning curves revealed that subjects differed markedly in performance on this task. Some learn the discrimination quickly, whereas others show different kinds of response patterns.     

Strategy changes in human contingency judgments as a function of contingency tables.

Judgment strategies of 169 undergraduate students on problems to judge the contingency between two binary events were identified by the method of rule-based analysis to clarify whether or not the strategies the subjects used would be affected by the concrete nature of the contingency table. Problems were constructed along two factors: total cell frequency and width of range of objective contingencies. Although the factor of total cell frequency had no effect on subjects' strategies, the number of subjects who changed strategies corresponding with problem instances increased when the objective contingencies were set closer to zero or when problems became more difficult. These results are discussed in the context of previous studies of this issue in the literature.     

Effects of oral cortisol treatment in healthy young women on memory retrieval of negative and neutral words

Studies in rodents have demonstrated that glucocorticoids enhance memory consolidation but impair delayed memory retrieval. Similar findings have been reported in humans. Emotional items are better remembered than neutral items. However, it is unknown if emotional valence influences the effects of cortisol on retrieval. In this double-blind crossover study, 16 healthy women learned a wordlist containing 15 neutral and 15 negative words. Delayed recall was tested 5h later. Cortisol administered before recall testing significantly reduced retrieval (p<.01). Exploratory follow-up analysis revealed that cortisol significantly impaired retrieval of negative words (p<.01), while having no significant effect on neutral words (p=.47). The current findings could suggest that emotional material is especially sensitive to the memory modulating effects of stress hormones.     

Unique temporal change is the key to attentional capture

Abstract— Attentional capture refers to the observation that some events break through and attract one's attention even when one is engaged in a task for which these events are irrelevant. Previous research, focusing primarily on spatial factors, has shown that a new object is more salient in this regard than an abrupt change in an object's features. Here we show that feature changes can be as effective as new objects in capturing attention, provided that they occur during a period of temporal calm. Conversely, both feature changes and new objects are far less effective in capturing attention when they occur simultaneously with other display changes, such as coincident with the initial onset of the display or with small visual transients that occur during a display transition. These results highlight the importance of considering both space and time in studies of attentional capture; the most effective stimulus is unique in both dimensions.     

Adult age differences in elaborations produced during prose recall

This study focused on adult age differences in the characteristics and quantity of elaborations produced during a prose recall task. Young (M = 24.3 years) and older (M = 67.9 years) adults were tested in 3 same-age, same-gender group size conditions: individual, dyad, and tetrad. Elaborations, which are statements not contained in the text but not inconsistent with it, were divided into 2 major categories. Denotative elaborations included statements that were closely related to the text and filled in gaps in the stories. These elaborations were equally produced by young and older adults and were significantly correlated with gist recall performance. Annotative elaborations were evaluative and interpretive comments. These statements were more frequently produced by older adults but were not correlated with recall performance. Young and older adults had different patterns of annotative elaboration production across group size conditions.     

A short scale to measure self-righteousness

Two studies were conducted which created and tested a scale to measure self-righteousness. Self-righteousness was defined as the conviction that one's behaviors or beliefs are correct, especially in contrast to alternate behaviors or beliefs. In the first study, a 4-item scale to measure general self-righteousness was derived which demonstrated adequate levels of internal consistency and was related to dogmatism and ambiguity intolerance. In the second study, the items were worded to be specific to running a race. This study succeeded in demonstrating that the scale possessed predictive validity. This study also demonstrated the usefulness of rewording the general items to make them specific about the content of self-righteousness.     

Improving the test-taking skills of learning-disabled students

16 learning-disabled second- and third-grade students were matched on previous years' achievement scores and grade and assigned at random to experimental and control conditions. Students in the experimental condition were given 8 20-min. sessions of training in test-taking skills particular to the Stanford Achievement Test. Analysis of test scores indicated trained students scored significantly higher on one subtest of a shortened version of the test than students who had not been trained.