A developmental study of choice reaction time: the effect of two forms of stimulus degradation on encoding.

To assess the effects of environmental enrichment, 156 normal, full-term institutionalized infants were randomly assigned to Group I (30 min per day of supplementary vestibular stimulation), Group II (30 min per day of supplementary vestibular-plus-verbal stimulation), or Group III (untreated controls). Stimulation began at about the age of 12 days and continued until the children were adopted, approximately 6 weeks later. Children were assessed at regular intervals on the Gesell Developmental Schedules, until the age of 27 months. Group comparisons revealed no significant treatment effects.     

Studies in observational paired-associate learning: Informational,social, and individual difference variables

Four experiments examined the relative importance of informational (proportion of correct responses and kinds of errors emitted by a model), social (model competency, sex of model, video vs. audio taped model), and individual difference (sex of subject, grade) variables in observational paired-associate learning. In Experiments I–III, vicarious subjects received cycles of study-model-test trials, while direct subjects were given the same sequences with intervening test or stimulus familiarization trials. In Experiment IV, vicarious subjects received cycles of study-test-model-test trials, while direct subjects received the cycles with a test trial replacing the model trial. No confirmation was provided on test and model trials. Whereas the effects attributable to social and individual difference variables were generally negligible, mere accuracy of the model's responses repeatedly covaried with performance on the last test trial of each cycle. Conditional analyses established that (1) vicarious facilitation is comparable across cycles and localized in items responded to incorrectly on immediately preceding test trials, and (2) observers learn fewer incorrect than correct model responses. Vicarious groups performed at reliably higher levels than direct subjects on model correct but not incorrect items. The results strongly suggest a close correspondence between direct and vicarious verbal learning principles and mechanisms.     

Transfer of a response controlling stimulus duration across discrimination problems

In the acquisition phase, pigeons learned to peck at a changeover key to shorten the duration of S? but not of S+ presented on the food key in a discrimination problem. In the transfer phase, the significance of S+ and S? was changed through extinction of both, equal reinforcement, or discrimination reversal, while the changeover key was not available. Transfer tests then showed appropriate modification of the changeover response. Similar transfer was demonstrated across orthogonal stimulus dimensions. Further analytic studies showed that this transfer of the changeover response did not depend upon mediation due to differential response rates to the food key. This research strategy enriches the study of the “second learning process” by providing an indicator of stimulus control in all phases of the procedure. Direct transfer between different problems also indicates that discriminative stimuli, although physically dissimilar, have the same “psychological value” for the subject.     

Immediate and delayed reinforcers for flavor preferences in rats

When rats received, on alternate days, one flavored saccharin solution for 5 min and a differently-flavored saccharin solution for 60 min, they showed no consistent preference between the flavors. On the other hand, when they received one flavor in a concentrated saccharin solution and a different flavor in a dilute one, they preferred the first flavor in tests with saccharin concentration held constant; also, rats learned to prefer a flavor immediately followed by a concentrated saccharin solution to one followed by nothing. They showed no consistent preference, however, between a flavor followed 30 min later by a concentrated saccharin solution and one followed by nothing; but they learned to prefer a flavor followed 30 min later by a dextrose solution to one followed by nothing. In other words, consummatory responding did not reinforce flavor preference, sweet taste did so with immediate but not delayed reinforcement, and nutrition did so even with delayed reinforcement.     

Asymptotic reinforced responding as a function of the operant level of the instrumental response

The relationship between operant level (base rate) and asymptotic reinforced instrumental responding was investigated in several contingencies in which licking was contingent upon running, under different FR schedules. For Group I the relationship was examined by selecting rats who naturally differed in their running base rates and for which the licking base rates were equivalent. For Group II the relationship was examined by selecting rats with equivalent running and licking base rates, but whose running rates were eventually made to differ by manipulating wheel-torque requirements. Asymptotic reinforced instrumental responding was found to be linearly related to pre-contingent running base rates, for all FR schedules, and independent of the procedures used to obtain differing running base rates. The results support Premack's contention that asymptotic reinforced instrumental responding is a joint function of the reinforcing response and the operant level of the instrumental response.     

One-way characteristic performance of rats under two-way signaled avoidance conditions

In Experiment 1, the conflict in a two-way active avoidance was reduced by allowing rats to avoid one of two levels of shock by running onto a safe platform which covered one half of the grid floor. Performance characteristics of one-way avoidance were obtained regardless of the shock intensity. Groups with no platform showed poor performance. Experiment 2 suggested that the facilitatory effect of the platforms was not due to the cue associated with platform removal. These results suggest that (a) rats can quickly learn to enter a spatially aversive location, (b) fast avoidance learning may be obtained in a two-way setting, and (c) rats seem capable of selective association of environmental and aversive stimuli.     

On the failure of transfer of control from separately conducted Pavlovian conditioning to free-operant avoidance conditioning in rats

In Experiment 1, presentation of a tone previously correlated with foot shock produced an increase in the rate of rats' foot-shock avoidance responding, while presentation of a tone previously correlated with tail shock had no reliable effect on the rate of foot-shock avoidance responding. In Experiment 2, a tone correlated with tail shock elicited heart-rate conditioned responses, but had no reliable effect on the rate of subsequent foot-shock avoidance responding. In Experiment 3, presentation of a tone previously correlated with foot shock, and a tone previously correlated with tail shock in separate groups produced increases in the rate of tail-shock avoidance responding. In Experiment 4, a tone correlated with tail shock in one setting accelerated tail-shock avoidance responding in a second setting. Interaction between US and negative reinforcer modifiability by skeletal responding may contribute to the pattern of results obtained.     

Belief similarity and attitude similarity as determinants of interpersonal attraction

It was predicted that attraction would be a function of both attitude similarity and belief similarity, but that attitude similarity would have the greater influence. In Expt I, 60 subjects were presented with strangers that were either similar or dissimilar on attitude and on belief. Attraction was a positive function of both attitude similarity (p < .05) and belief similarity (p < .01). Experiment II replicated and extended Expt I with the addition of a 50% similar group for both attitude and belief. Attraction was a positive linear function of both attitude similarity (p < .001) and belief similarity (p < .02); departure from linearity was not significant. Attitude similarity also had greater effects on other aspects of interpersonal evaluation than belief similarity. The results were discussed in terms of the locus of reinforcement of attitude similarity and of belief similarity.     

Generality and topic specificity of cognitive styles

A multitrait-multimethod strategy was used to assess eight structural properties of cognition applied to several classes of objects by 88 university students in Boulder, Colorado, United States, and 80 university students in Kyoto and Otsu, Japan. Each cognitive style was found to display some degree of generality over object classes and also some degree of class specificity. It is concluded that cognitive style depends on the subject, the class of objects considered, and an interaction between the two.     

The meaning of observed violence: Real vs. fictional violence and consequent effects on aggression and emotional arousal

Sixty male subjects were either attacked or treated neutrally by a confederate, after which each saw a videotape of two men fighting. Subjects were informed that fight was either real or fictitious or were given no explanation of it. Subjects who had previously been attacked and had observed the fight under a set to perceive it as real were subsequently more punitive in their treatment of the confederate than subjects in all other conditions. The combination of prior attack and observation of real violence also sustained blood pressure (BP) at near the level produced by the attack, whereas BP of attacked subjects in the other conditions declined during the time the fight was observed. Palmar sweat measures revealed that observation of real violence was more arousing than observation of fictitious fighting. The results are discussed in terms of the effects that the reality of observed violence has on emotional arousal.