Reliability of electrodermal habituation measures under two conditions of stimulus intensity

The present study investigated test-retest reliability of habituation of the evoked skin conductance response. Subjects received 20 presentations of a 1000-Hz, 3-sec tone at the same time of day on two separate occasions, separated by an interval of 97–160 days. Thirteen subjects received stimuli of 90 dB, while for 24 subjects, stimulus intensity was 70 dB. Interstimulus interval was 21 sec for both groups. Both absolute rate of habituation and trials to criterion displayed moderate reliability, and the relationships between habituation measures and other aspects of electrodermal activity were in agreement with previous findings.     

GSR as reflection of decision-making under conditions of delay

A total of 15 healthy individuals of both sexes, aged from 18 to 30 years, were studied. The subjects were presented a series of three audio signals in each of two conditions. Under condition A the subject made a fist immediately after the third signal if all the three sounds were identical; under condition B, a fist was made if at least one sound was different from the other two. The GSR was particularly pronounced when the decision to make or not to make a fist was made under conditions where action was delayed.     

Force gradients in stimulus generalization

Pigeons were trained to peck with differing force requirements on a key specially designed to measure and control force of pecking without changes in the mechanical threshold. Following training on a key illuminated by a single wavelength, a generalization test was given. Force and rate gradients were obtained. Force gradients were shown to have a form similar to rate gradients. The slope of the force gradients was a direct function of the force of responding at the conclusion of training. Rate gradients were independent of the force of responding.     

A generalization of stimulus sampling theory

A modification of stimulus sampling theory is presented. The restriction that each stimulus element is conditioned to one and only one response is replaced with the notion of a scale of conditioning for each element. This variation provides a context in which such variables as reward magnitude and motivation can be viewed as determiners of behavior. Some experimental results on multiple response problems also have a natural interpretation in terms of these ideas.     

Instructions and stimulus categorizing in a measure of stimulus generalization

In Experiment I, three groups of 20 Ss each were exposed to a light of 550 mμ (yellowish-green) for 60 sec and then viewed a random sequence of wavelengths with instructions to respond only to the original color. The instructions given the three groups were worded differently in an attempt to vary the strength of a set-to-discriminate assumed to be created by this procedure. The three groups produced similar gradients, each with a peak of responding at 540 mμ, in agreement with Kalish's (1958) published gradient for the 550 mμ standard stimulus value. It was suggested that the nature of the task is such that a strong discriminatory set is produced regardless of the wording of the instructions.

A temporal analysis of the gradient as it develops during the testing revealed that initially the peak of responding occurs at 550 mμ; but as testing progresses, it shifts gradually in the direction of the shorter wavelengths (purer greens). Experiment II was performed to test the generality of the phenomenon of regression to the primary color. Two groups of 20 Ss each were tested for generalization following exposure to 510 mμ (bluish-green) and 525 mμ (pure green), respectively. We predicted that the 510 mμ gradient would reveal a progressive shift toward the longer wavelengths (purer greens), whereas the 525 mμ gradient would show no tendency to shift. The results were strikingly in accord with these predictions.

We concluded that although a physiological process could not be ruled out, the verbal labeling of the standard stimulus value may well be responsible for the regression of the gradient toward the primary color.

     

Response patterning during stimulus generalization in the rat

Nine rats were trained to bar press in the presence of a clicking sound of 6.67 cps (S(D)) for 1-min variable-interval food reinforcement randomly alternated with a clicking sound of 20 cps (S(Delta)) signifying extinction. After a criterion of 90% of total responses in the presence of the S(D) was obtained, a generalization test was administered, including values of 6.67, 10.00, 13.33, and 20.00 cps, with responses in the presence of the S(D) continuing to be reinforced during testing. The test yielded a gradient of response strength with rate highest in the presence of the S(D) and decreasing with increasing distance from this value. An interresponse time (IRT) analysis of responding during generalization testing revealed no systematic differences in modal IRT category or in median IRT to the different test stimuli. Mean IRT was lowest in the presence of the S(D) and increased systematically with increasing distance from this value, supporting the hypothesis that the generalization gradient of response rate is primarily the result of an increasing proportion of "long" IRT responses to stimuli increasingly distant from the S(D).