Searching for a pre-specified target letter in briefly displayed words and unpronounceable non-words

Two experiments were designed in which subjects searched briefly displayed and masked arrays of letters for a single pre-specified target. The target was randomly located at one of twelve positions, its identity remained constant throughout, and it was embedded either in the context of words or in a context of unpronounceable strings of letters. In experiment 1 the letters were arranged in two six-item rows, and word and non-waord displays were mixed and presented to a single group of subjects. Accuracy of search was superior when the letters formed words, both for responses scored for correct position and for responses scored for correct row. In experiment 2 word and non-word displays were presented to different groups of subjects, and for both groups the twelve characters were either arranged as before in two rows or were positioned at loci representing the clock positions. Accuracy of search was again superior when the letters formed words and were arranged in rows, but there was no advantage for words when the letters formed a circle. These findings, firstly, indicated that the “word-superiority effect” obtained in experiment 1 was not a result of subjects adopting a word processing strategy for all stimuli, and secondly, they suggested that the word information could not be used to advantage in the absence of spatial cues delineating the words and/or when the letters were not positioned in the usual horizontal arrangement. It was concluded that the results of both studies were consistent with a perceptual account of the word superiority effect.     

Rule learning in children: Multiple-set training and intermediate-size transposition

Two experiments were conducted in which the subjects were trained to choose the middle-size stimulus in either a single stimulus set or in each of two nonoverlapping stimulus sets. Following criterion, each subject was presented with a series of 12 test trials involving a new stimulus set. In Experiment 1, kindergarten children tended to choose the middle-size test stimulus if the test set consisted of stimuli intermediate in size to the stimuli in the smaller and larger training sets. When the test stimuli were all larger than any of the training stimuli, the probability of choosing the middle-size stimulus increased as the distance between the two training sets increased. Three groups of children participated in Experiment 2: a kindergarten group, a first-grade group, and a first-grade group that experienced middle-size training a year earlier. The distance between training sets and two training procedures affected the three groups in a similar manner during acquisition, but several interactions were obtained during the test. The findings were discussed in terms of the Lane and Rabinowitz (D. M. Lane & F. M. Rabinowitz, Child Development, 1977, 48, 412–426) rule based theory of intermediate-size transposition and suggestions were made as to how children acquire the concept of middle.     

Duration discrimination is better with food access as the signal than with light as the signal

In Experiment 1 a go/no-go discrimination procedure was used to compare control of five pigeons' keypecking by food-access duration with control by light duration. Pecks to an illuminated key were reinforced with grain following 10-sec presentations of food access or houselight, but not after 5-sec presentations of either stimulus. Each subject discriminated food-access duration faster and to a greater degree than light duration. In four between-subject replications, pigeons discriminated food-access duration better than the duration of a localized light, the feeder light and a keylight, and with either water or food as reinforcement. In Experiment 2 control by durations of food access and light was compared using a conditional right-left choice procedure (two pigeons), and a delayed symbolic matching-to-sample procedure (six pigeons). Under both, choice accuracy again was higher on food-access trials. The results of Experiment 3, in which two pigeons received generalization trials with durations of food access and light that were intermediate to the training values, confirmed that responding was controlled by the duration dimension of both food access and light. The superior control by food access is consistent with previous evidence that food is an effective and memorable stimulus, possibly because of its biological importance. These results also provided empirical support for the commonly made assumption that stimuli differ in effectiveness. As well, the results show that the stimulus to be discriminated can play an important role in the accuracy of duration disciminations, a fact which has implications for the study of temporal discriminations in animals.     

Personality and the effects of stress on recognition memory

The experiment examined the contribution of anxiety, extraversion, neuroticism, and psychoticism to recognition memory for pictures and words using a signal detection method. Independent groups of subjects performed a recognition memory task under one of four conditions (control, noise, threat, and reward) that was intended to capitalize on dispositions which characterize the personality dimensions. In an ego threat condition involving personal evaluation, introverts displayed a performance decrement relative to noise and reward conditions. Psychoticism was inversely related to performance in the noise and threat conditions and directly related in a reward condition. In general, J. A. Gray's (1981) model of anxiety and impulsiveness accommodates much of the data, but the mechanisms which mediate the influence of personality on memory performance are not clear.     

Processing of visually presented vowels in the cerebral hemispheres

The respective efficiency of the cerebral hemispheres in processing visually presented vowels is discussed and examined in a tachistoscopic experiment with normal subjects. It is suggested that results from dichotic listening experiments cannot be used to predict performance on the same material in the visual modality. The physical characteristics of the stimulus, in both modalities, contribute to the pattern of hemispheric advantage and cannot be ignored in the interpretation of results from dichotic listening and tachistoscopic experiments.     

Hemispheric lateralization in 47,XXY Klinefelter's syndrome boys

Thirty-two boys with a 47,XXY karyotype were compared with chromosomally normal male controls in their performance on six tasks of hemispheric specialization. The results revealed that the 47,XXY subjects had smaller asymmetries on left hemisphere tasks and larger asymmetries on right hemisphere tasks than controls. Analyses of individual right and left side scores revealed that the atypical lateral asymmetries of the 47,XXYs were due to a shift toward greater right hemisphere involvement on four of the six measures. It was postulated that the slower fetal growth rates of the extra X chromosome group might contribute to their atypical hemispheric specialization and the failure of their left hemisphere to gain dominance over their right in language processing.     

Reciprocal heuristics: A discussion of the relationship of the study of learned behavior in laboratory and field

At the turn of the century, the initiators of laboratory study of animal learning advocated two very different approaches to the subject matter. Willard Small favored the investigation of learning in ecological settings appropriate to individual species. E. L. Thorndike treated the process of association formation in animals as a general one, best studied in situations distant from those to which subject species were adapted. The latter view dominated laboratory study of animal learning for 80 years. The consequent absence of ecological content from laboratory investigations of animal learning, together with recent expansion in knowledge of the behavior of free-living animals, has created opportunities for ecologically sound investigations of animal learning of the type first advocated by Small. Studies of taste-aversion learning, although introducing evolutionary issues into the study of animal learning, do not exemplify such an approach. Integration of field and laboratory studies of behavioral plasticity in animals requires a change in the methods used to select phenomena for analysis. Such integration does not often lead to identification of the behavioral processes underlying the development of particular behaviors observed in nature. Rather, its results are an increase in the variety of learning processes investigated in laboratory settings and enhanced understanding of the behavioral capacities of subject species.     

Memory and rehearsal characteristics of profoundly deaf children

This study examined whether a deficiency in spontaneous strategy use accounts for deaf children's verbal short-term memory performance. Various colors were presented for 3 s each, followed by a 15-s recall delay. The delay was either unfilled, or subjects were induced to rehearse or were prevented from rehearsing. Sixty-four deaf students from oral and total communication settings, 5 to 15 years of age, were tested. The spontaneous rehearsal of both deaf samples seemed to emerge later than the hearing sample's, and it was both inefficiently implemented and less effective in mediating recall than hearing children's. However, when rehearsal was prevented or was induced in all samples, the deaf recalled as well as, or better than, the hearing. Implications discussed include the need to compare both spontaneous and controlled strategy use in developmental memory studies, and the need to provide additional training for deaf children in the strategies of remembering, as opposed to the content material.     

Extinction of morphine analgesic tolerance

It has been suggested that the analgesic effect of morphine becomes attenuated over the course of successive administrations by a conditional, compensatory, hyperalgesic response elicited by the administration procedure, thus accounting (in part) for analgesic tolerance. On the basis of this associative model of tolerance, it would be predicted that established tolerance would be extinguished by placebo sessions. In experiments of apparently similar design (but conducted by different experimenters in different laboratories), data both confirming and refuting this prediction have previously been published. The present experiment, conducted jointly by the experimenters who reported the divergent findings, was designed to determine the reasons for the different results. It was found that placebo sessions do consistently attenuate morphine analgesic tolerance. Such extinction is not limited to the experimenter, drug preparation, rat strain, or apparatus used in the original, successful demonstration of the phenomenon, but rather is also demonstrable under conditions similar to those used in subsequent experiments which failed to demonstrate extinction of tolerance. Results of the present experiment suggest that the failures to demonstrate extinction of tolerance were attributable to insufficient extinction training.