Two successive learning situations were observed for four groups of 5s with differential electrodermal responding to two stimuli as the dependent variable. Major independent variables were interstimulus interval (ISI) (.5 sec. and 7.0 sec.), the presence or absence of CS-UCS pairing in the initial phase of training, and a reversal of stimulus relations between sessions for the group with initial CS-UCS pairings. The 5s were fully informed of stimulus relations. Both ISI groups showed discrimination learning in the initial phase, and for both groups, discrimination reversal was immediate. Results are discussed in terms of potency of verbal determiners of differential responding with electrodermal behavior and the effects of instructions on overall level of responding to stimuli.
A within-Ss comparison was made of two related procedures for negatively correlating a signal, or conditioned stimulus (CS), with a shock unconditioned stimulus (UCS) in differential conditioning of electrodermal responses (EDRs). One operation presented a nonreinforced stimulus (CS -) during reinforced trials for a second stimulus (CS+). The other reinforced a stimulus (CS+) whenever it occurred alone, but never reinforced a compound composed of that stimulus and a second (inhibitory) stimulus (CSA). The conclusion that the CS-and CSA developed inhibitory properties was based on three classes of results: (a) during acquisition, there was clear differential responding to stimuli positively and negatively associated with the UCS; (6) on transfer trials, smaller responses were given to compounds of excitatory and inhibitory stimuli than to the excitatory stimuli alone; and (c) subjective judgments of expectation of shock paralleled the EDRs.
Three experiments observed differential electrodermal responding to signal stimuli (CSs) by contrasting positive, random, and negative contingencies between the signals and strong stimuli (UCSs). Experimentation began as a test of the proposition that electrodermal response to a random signal (or CSR) would lie between the response to a reinforced or excitatory stimulus (CS+) and that to a nonreinforced or inhibitory stimulus (CS- or CSI). A clear intermediate position for CSR did not result. Instead it appeared that CSR was operating as a mildly excitatory signal. This led to a second experiment where response to pairs of stimuli with different contingent relations could be compared in independent samples. The pairs were CS+ and CS-, CS+ and CSR, and CSR and CS-. Differential responding was observed in all pairs and response to CSR was significantly larger in the group receiving CSR with CS- than it was in the group receiving CSR with CS+. A contingency contrast effect was suggested. A third experiment explored the implications of a contingency contrast effect by varying overall UCS density, the duration of "safety intervals," and the presence or absence of instructions about contingencies. The UCS density and instruction variables influenced the differential performance to CSR and CS-, a result that was interpreted as further evidence for a perceptual contingency-contrast effect. Some theoretical implications of such a contrast phenomenon are examined, as they apply to autonomic learning. The CS is interpreted as a signal supplying contingency information that is dependent upon a complex of factors in the stimulation environment.
The effects of three types of certainty information about aversive white noise stimuli on anticipatory and unconditioned electrodermal responses (EDRs) were studied in a group of 48 subjects within a paired stimulation paradigm. Event certainty was manipulated by making UCS occurrence predictable for some groups and not for others. Time certainty was manipulated by presenting constant interstimulus intervals (ISIs) to some groups and variable ISIs to others. Quality certainty was varied within groups by having UCS intensity predictable for one CS and not for others. All three types of certainty affected anticipatory and unconditioned response magnitudes. Event certainty alone resulted in significantly larger magnitUdes of anticipatory EDRs, while all three types of certainty tended to result in smaller magnitUdes of response to the aversive UCS. The three types of certainty tended to summate, producing larger anticipatory responses and smaller unconditioned responses in conditions with more different classes of certainty information.
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