Effects of differentially modeled stimuli on vicarious autonomic arousal

The present study examined effects of variations in modeled pain cues on level of vicarious arousal, using heart rate and blood-volume amplitude as psychophysiological measures. Students were assigned randomly to one of four groups in which they either (a) underwent directly the cold-pressor test, (b) observed a model exposed to the cold-pressor test and expressing pain by facial and bodily movements, (c) heard only the modeled verbal expressions of pain, or (4) observed the model express neither verbal expressions nor physical movements while undergoing the painful stimulation. The results show aversive stimulation increases heart rate whereas vicarious aversive stimulation produces reductions in heart rate. The deceleration of heart rate was not found in response to all three forms of modeling. Both direct and vicarious aversive stimulation produced decreases in the amplitude of vasomotor responses. The size of the decrement between direct stimulation and the minimal modeling condition of vicarious arousal showed significant differences, but differences between direct stimulation and the maximal modeling condition were not significant. The vasoconstriction was found in response to two forms of modeling.     

Enhancement of conditioned autonomic responses in monkey when preshock signals occasion operant suppression.

Classical pairings of a sound stilulus with shock elicited larger magnitude and more rapidly conditioned autonomic responses when subjects were responding on variable-interval schedules for food than when they were eating freely available food. The difference was not attributable to changes in control values of heart rate and blood pressure, or to alterations in motor activity, but appeared related to operant suppression.     

One-trial learning and superior resistance to extinction of autonomic responses conditioned to potentially phobic stimuli.

Human subjects were exposed to pictures of potentially phobic (snakes) and supposedly neutral (houses) objects as conditioned stimuli (CSs) in a Pavlovian conditioning experiment with shock as unconditioned stimulus (US), and skin conductance and finger pulse volume as dependent variables. The skin conductance responses conditioned to phobic stimuli were acquired after one CS-US pairing, and showed practically no extinction, whereas the responses to neutral stimuli showed very little resistance to extinction after both 1 and 5 reinforcements. The superior resistance to extinction of the phobic condition was interpreted to be a specific associative effect. In general, the skin conductance acquisition data showed tendencies similar to those during extinction. For finger pulse volume responses, however, there were very weak conditioning effects, and no effect of stimulus.     

Differentiation between vicarious instigation and classical conditioning of electrodermal responses

In past research of vicarious conditioning when a conditioned stimulus (CS) was repeatedly presented both to a model and an observer, the observer's reaction to the CS may have been the result of a vicariously conditioned reaction to the CS, as well as a vicariously instigated reaction to the inferred emotional state of the model who anticipates the reception of a noxious stimulus when the CS is presented. In order to partial out these two reactions, the present experiment employed 32 subjects of both sexes who took part in a two-group study of differential, vicarious classical conditioning of skin conductance responses. In one of the group, the tones serving as CS+ and CS- and which preceded the aversive and non aversive events to the mode, were presented over earphones to both the confederate model and the observer subject. In the second group, only the subjects had earphones on and were led to believe that the model was not aware of the CS presentations. This eliminated the possibility of vicariously instigated reactions. Although the conditioning effects produced in the present study were somewhat weak, results clearly showed equal levels of vicarious instigation and conditioning in the two groups. These results indicate that the potential confounding of these two reactions studies has not significantly affected result or conclusions from previous studies.     

Heart-rate and electrodermal orienting responses to visual stimuli differing in complexity

Orienting response (OR) theory predicts that amount of information in the stimulus, or stimulus complexity, should be an important determinant of OR elicitation and habituation, more intense and more slowly habituating ORs being expected to complex than to simple stimuli. This prediction was tested in an experiment where subjects were exposed to simple and complex visual stimuli in randomized order, while heart-rate and skin conductance were measured. Complex stimuli evoked a more pronounced deceleratory heartrate response than did simple stimuli. However, the two conditions did not differ in rate of habituation of this response. For skin conductance responses, on the other hand, the complex stimulus took more trials than the simple stimulus to reach habituation, whereas the two conditions did not differ in response magnitude. Thus, the hypothesis of more intense orienting to complex stimuli was supported by the heart-rate data, and that of slower habituation to complex stimuli, of the skin conductance data.     

The skin-flushing response: autonomic, self-report, and conditioned responses to repeated administrations of alcohol in Asian men

This study examined the skin-flushing response in Asian men, which is a low-risk factor for alcoholism. Asian men who did and did not flush to alcohol consumed 0.5 g/kg ethanol during three sessions with alcohol, and placebo in a fourth session. The results indicated that: (a) Asian men who flushed to alcohol showed pronounced cardiovascular changes that did not exhibit differential tolerance over 3 sessions, (b) there were surprisingly few self-reported mood differences in response to alcohol between those who did and did not flush, and (c) finger-pulse amplitude decreased and self-ratings of "boastful" increased significantly in response to placebo challenge in those men who did not flush. These results raise questions about the psychological mechanisms by which the skin-flushing response inhibits the development and expression of alcoholism.     

The relation of vicarious to direct instigation and conditioning of electrodermal responses

Abstract.— Three groups with 16 Ss each and run in pairs, participated in a differential, successive components, long interstimulus interval conditioning paradigm with the skin conductance response as dependent variable. For the problem solving group the task was described as guessing which of two lamps (CS₂s) would follow after two different tones (CS₁s). In the observer group they were further informed that the other subject in the pair, the model, would receive shocks at CS+ offset, which actually was the case for the model group. Skin conductance responses were scored in five intervals during and after the non-overlapping presentation of the two CSs with a duration of 8 sec each. The results indicated no differentiation in any interval for the problem-solvers, and parallel instigation to shock and threat of shock, and conditioning in the observer and model groups, with the exception of conditioning in the 1st interval for observers only. The results were interpreted as parallel instigation and conditioning between vicarious and direct learning, the reported difference being due only to different UCS-intensities causing a blocking of first-order conditioning in the model but not in the observer group.     

Manipulating affective state influences conditioned appetitive responses

Affective states influence how individuals process information and behave. Some theories predict emotional congruency effects (e.g. preferential processing of negative information in negative affective states). Emotional congruency should theoretically obstruct the learning of reward associations (appetitive learning) and their ability to guide behaviour under negative mood. Two studies tested the effects of the induction of a negative affective state on appetitive Pavlovian learning, in which neutral stimuli were associated with chocolate (Experiment 1) or alcohol (Experiment 2) rewards. In both experiments, participants showed enhanced approach tendencies towards predictors of reward after a negative relative to a positive performance feedback manipulation. This increase was related to a reduction in positive affect in Experiment 1 only. No effects of the manipulation on conditioned reward expectancies, craving, or consumption were observed. Overall, our findings support the idea of counter-regulation, rather than emotional congruency effects. Negative affective states might therefore serve as a vulnerability factor for addiction, through increasing conditioned approach tendencies.