The effect of temporal distribution in relation to constant frequency of stimuli on habituation of the orienting reaction

The lack of empirical evidence for faster habituation with the regular presentation of stimuli suggests that it is not the constancy of presentation of stimuli, but rather the rate of stimulation--defined as the reciprocal of the harmonic mean of the interstimulus intervals--that determines the speed of habituation. Using alternation of 10-70 and 30-50 sec and a constant sequence of 40 sec, three different rates of stimulation were realized. The hypothesis of faster habituation of skin conductance reactions with higher rates of stimulation was not confirmed. However, a consistent pattern of skin conductance reactions, with an increase in reaction after long intervals and a decrease after short intervals, was found, especially in the group with alternating intervals of 10 and 70 sec. The analysis of an additional group with a random sequence of intervals showed that the response pattern did not result simply from the expired time since last stimulus, i.e., a simple mechanical effect. The possibility of anticipating the stimuli and differing information content of the stimuli are discussed as possible determining factors.     

GSR amplitude instead of GSR magnitude: Caveat emptor!

Size of GSR made by 300 Ss to 20 repetitions of a visual stimulus is presented as mean magnitude and mean amplitude, illustrating that the amplitude method (averaging only those responses which are greater than zero) is susceptible to distortion resulting from a systematic elimination of Ss who initially make small responses. From trial to trial, the amplitude function comes more and more to be due to the behavior of Ss who initially make large responses. Even though the latter Ss’ responses actually reduce across trials, the amplitude function rises. Magnitude (including zeroes) docs not suffer from this distortion. It is suggested that the definition of a zero response is the source of the problem.     

Paired comparison scaling of reaction potential in two different experiments on habituation

Thurstone’s method of paired comparisons was employed to obtain scaled values of reaction potential from two completely different experimental situations involving response decrement. The first was one in which the GSR was measured on 10 repeated presentations of a visual stimulus (N= 89). The second involved 80 presentations of ordinary visual scenes; the S looked at each scene as long as he wished before switching to the next (i.e., looking time was measured. N=80). Scaling reaction potential by Thurstone’s method provided a common operational definition for both sets of data and permitted their direct comparison in identical units. Both measures showed substantial decrement in reaction potential across stages, with the GSR scale values dropping steeply from the first to the second trial and. thereafter, following a course of decline similar to the looking time scale values. Tlie correlation of the two sets of scale values was essentially linear and equalled 0.90.     

Autonomic concomitants of discriminative avoidance and punishment training in the monkey

TwoCebus albifrons monkeys were trained to press a back-lighted panel to postpone a brief electric shock to the tail using a Sidman avoidance schedule (SS = 40 sec, RS = 40 sec). After 25 training sessions, a discriminative schedule was introduced, with the Sidman avoidance continuing in the presence of one discriminative stimulus and punishment introduced in the presence of the other. The discriminative stimuli were colors on the panel. Discriminative training also involved 25 sessions, each with a random sequence of 6 avoidance and 6 punishment segments, with 30 sec intervals between the segments. Plantar skin conductance and heart rate were recorded along with the panel-pressing behavior. The two monkeys adjusted to the discriminative schedule quite differently from one another. One animal responded at a high level and avoided very well (during avoidance) but was punished frequently (during punishment). The other animal responded less frequently and received many shocks during avoidance but almost none during punishment. The animal that showed less ability to inhibit responding (and received about four times as many shocks overall) appeared to have discriminated better temporally in spacing its responses during avoidance training. The monkey whose panel-pressing behavior resulted in more shocks also tended to show a higher tonic level of autonomic arousal. However, within-animal differences in shock frequency (between avoidance and punishment) were not similarly related to autonomie arousal. The animal that received fewer shocks overall (but more during avoidance) showed greater arousal during punishment. The animal that received more shocks overall (but fewer during avoidance) showed no arousal differences between avoidance and punishment.     

Notes from "Pavlov's Wednesdays": sensory preconditioning.

Sensory preconditioning was first demonstrated in Pavlov's laboratory in 1931/32, rather than discovered by Brogden in 1939. Pavlov included nonassociative controls, forward pairing of the indifferent stimuli before reinforcing the second one with shock, and he avoided the development of inhibition to the compound by using a moving visual stimulus and a sound like that of scurrying mice, which both had persistent orienting reactions. Pavlov concluded that the indifferent stimuli were associated by temporal contiguity similar to human associations between successively spoken works. He did not consider the possibility of mediation via the orienting reactions.     

Avoiding heterosexist bias in psychological research

The authors describe various ways that heterosexist bias can occur in scientific research and suggest ways that social and behavioral scientists can avoid it. Heterosexist bias is defined as conceptualizing human experience in strictly heterosexual terms and consequently ignoring, invalidating, or derogating homosexual behaviors and sexual orientation, and lesbian, gay male, and bisexual relationships and lifestyles. The deleterious scientific, social, and ethical consequences of such biases are discussed. Questions are provided for researchers to use in evaluating how heterosexist bias might affect their own selection of research questions, sampling, operationalization of variables, data collection, protection of participants, and dissemination of results. Suggestions also are offered for reducing heterosexist bias in academic journals, in textbooks, and in colleges and universities.     

Blocking and unconditioned response diminution in human classical autonomic conditioning

This paper summarizes the results of three experiments on blocking and unconditioned response diminution in human SCR conditioning. Recent theories of conditioning propose that reduced processing of the unconditioned stimulus due to conditioning results in reduced unconditioned response magnitude and in blocking of conditioning of a second conditioned stimulus when it is in compound with the previously conditioned stimulus. In these experiments, clear evidence of diminution of the unconditioned response was obtained in all three studies, but blocking was found only in the third study, which employed a within-subject design and in which the blocking was observed only after at least one extinction trial on both the blocked and nonblocked stimuli. Order of testing was not a factor in this delayed blocking effect. These results do not support the view that blocking occurs because of reduced processing of the unconditioned stimulus in the unconditioned response diminution sense.