The Effects of Paced Tapping on Heart Rate, Skin Conductance, and Muscle Potential

The use of a tapping response as an indicant of interest or preference in studies of the physiological correlates of attitude and attitude change is discussed. The physiological effects of paced tapping, using rates that might be employed in attitudinal studies, were examined under conditions free of attitudinal import. Major findings were: (1) There is no significant difference in the effect on HR with rates up to 3/sec. (2) There is no significant difference in the effect on SCL with rates up to 7/sec. (3) When raw EMG scores are used as the basis of analysis no significant differences are found with rates up to 3/sec; however, when the square root transform of this variable is used, a significant effect is found for all rates used in at least one of the phases of the experiment. The results, taken as a whole, indicate the possibility of either controlling or mathematically compensating for the physiological effect of the tapping response, per se, in attitudinal studies.     

Anxiety and the Habituation of the Skin Conductance Response

The effect of threat of shock on the habituation of the skin conductance response (SCR) to a series of auditory stimuli was assessed. Skin resistance and heart rate were recorded during the presentation of 20, 1 sec, 1000 Hz tones in a control session and in a session at the end of which subjects were led to expect a painful electric shock. The effects of the threat of shock consisted of recovery of the SCR and an increase in skin conductance level and heart rate. They were restricted to the period during which subjects believed the shock to be imminent. Two possible reasons for the SCR recovery were offered, one in terms of Lader and Mathews' (1968) ‘maximal habituation’ hypothesis and a second in terms of a change in the stimulus complex.     

Interaction of a Motor Response, and Reaction Time and Time Estimation Tasks, on Heart Rate and Skin Conductance

The influence of motor responding and typical psychophysiological tasks on heart rate was tested by manipulating motor requirements of reaction time (RT) and time estimation (TE) tasks. Thirty-four volunteers were assigned randomly to four groups. Two groups squeezed a hand dynamometer at the start of a trial and the other two groups squeezed at the finish of the trial. The force of the squeeze was also manipulated: either 3 kg (3) or 7 kg (7). The four groups were Start 3, Start 7, Finish 3, and Finish 7. All subjects participated in the TE and RT tasks. The dependent variables were measurements of forearm flexor muscle tension, heart rate and skin conductance. It was found that the manipulations of when and with what force a person squeezed the dynamometer resulted in reliable group differences in muscle tension. The magnitude of acceleratory components of the triphasic (acceleration-deceleration-acceleration) cardiac response was amplified by tension. The magnitude of the deceleratory component seemed to depend on both muscle tension and stimulus processing. Except for the magnitude of the response-bound deceleration, RT and TE produced very similar heart rate responses, and skin conductance did not differ among groups. The data were interpreted as providing evidence that motor response acts as an amplifier for the phasic HR produced by common psychological paradigms.     

Heart Rate and Skin Conductance in Anticipation of Shocks With Varying Probability of Occurrence

In Experiment I,Ss in each of four groups were given 8 shocks in either 8, 11, 16, or 32 trials, confounding probability with number of trials. Each trial was a countdown period of 30 sec, with an ITI of 30 sec. There were no shock probability effects using either heart rate (HR) or skin conductance (SC), with respect either to average within trial changes or to average pre-shock levels relative to rest. In every group after a large acceleration in Trial 1, HR subsided and stabilized; SC rose steadily throughout the session. In Experiment II, Ss in each of four groups were given either 5, 10, 15, or 20 shocks in 20 trials, confounding probability with number of shocks. In addition to the large HR acceleration in the first trial, there were in this case between-group differences in HR, which were a direct function of number and probability of shocks. Skin conductance did not discriminate the groups, though it rose in all groups both within and across trials. Experiment III, a partial replication of Experiment II, showed that the HR differences in Experiment II failed to repeat when the shock intensity was reduced; and SC no longer increased over trials.     

Attention and Vigilance: Performance and Skin Conductance Response Changes

The skin conductance response component of the orienting reflex was used to measure changes in attention during vigilance performance in order to test several hypotheses which have related aspects of vigilance performance to the occurrence and habituation of orienting or observing responses. Subjects detected irregularly presented visual signals among similar visual events during two 30-min tasks. Skin conductance responses were analyzed in epochs of time immediately preceding and following signals and in nonsignal-related time epochs. Magnitudes of skin conductance responses declined in both signal-related epochs (pre and post), but this decrement was correlated with performance changes only in the post-signal epoch. There was no decrement in SCR magnitudes during the nonsignal-related epochs. Skin conductance response magnitudes were significantly larger both before and after detected signals compared to misses. The data support the hypothesis that changes in vigilance performance over time are related to habituation of the orienting reflex evoked by signals. They also suggest that attentional processes preceding signals are related to successful detections.     

Effects of Changes in Verbal Stimuli on the Skin Conductance Response Component of the Orienting Response

This paper presents three experiments which were designed to investigate the effects of changes in verbal stimulus meaning on magnitude of the skin conductance response (SCR) component of the orienting response (OR). In Experiments 1 and 2, subjects received 12 visual presentations of a single word stimulus followed by a test trial involving change. The results of Experiment 1 (N = 48) indicated that a test stimulus which constituted change in meaning and taxonomic category induced larger responses than did a change in meaning alone, which in turn induced larger responses than did a control condition of no change. Experiment 2 (N = 64) investigated the effects of both semantic and acoustic changes and the results indicated that only semantic changes resulted in test trial SCRs which were larger than those in the control condition. Experiment 3 (N = 48) investigated the effects on SCR magnitude of within- and between-taxonomic category shifts following habituation training with 4 examples of the category. In this case, only the between-category change resulted in SCRs which were larger than those in the control condition of no change. The results of all three experiments were interpreted as support for Sokolov's (1963) claim that the meaning of verbal stimuli is encoded during habituation. Moreover, the results of Experiment 1 indicate that responsiveness on a change trial is a positive function of the amount of change, while the results of Experiment 3 suggest that when a number of examples of a word class are employed during habituation, the semantic characteristics of that class are encoded.     

Interactions of Marijuana and Induced Stress: Forearm Blood Flow, Heart Rate, and Skin Conductance

To examine the interaction of marijuana and an induced state of stress, on both subjective and physiological measures, two groups of 15 subjects each were given a mental arithmetic task to perform. The sequence of events was 10 min each of pre-stress, stress, post-stress, intoxication (about 20 min), pre-stress, stress, post-stress. In the intoxication phase, one group smoked marijuana containing 14 mg Δ⁹-THC while the other group smoked a placebo. The dependent variables were forearm blood flow (FBF), heart rate (HR). and skin conductance (SC), and a subjective measure of stress–the Multiple Affect Adjective Checklist (MAACL). The results revealed all physiological variables to be reactive to the stress task. In addition, marijuana intoxication produced reliable increases in both pre-stress HR and FBF, and yet the physiological response to the post-intoxication stress period showed no significant decrement when compared In the placebo group. Discussion of these results centered around marijuana's effects on tonic and phasic reactivity.     

Skin Conductance Responses in Unmedicated Recently Admitted Schizophrenic Patients

Skin conductance responses to repeated identical stimuli (11 or 21 tones, 85dBA, 1000 Hz, 1-sec duration, sine wave, fast onset) were studied in unmedicated recently admitted RDC diagnosed patients (13 schizophrenic and five paranoid psychotic) and in age- and sex-matched controls. Subjects were classified as nonresponders, fast habituators, habituators, and nonhabituators. The distribution did not differ between patients and controls. There were no nonresponders among the patients and no evidence of bimodality. Schizophrenic patients had more skin conductance responses than controls and a more irregular response course. Analyses of heart rate responses excluded defensive responses, but no conclusions could be drawn as to whether startle or orienting responses had been elicited. The patients had psychophysiological signs of high arousal. They were in an early phase of their illness, with “positive” psychotic symptoms. The absence of nonresponding may be related to the type of patients studied and the characteristics of the stimuli used (high intensity, fast onset tones).     

Stimulus Omission and Dishabituation of the Skin Conductance Response

Three experiments investigated the effects on the skin conductance response of S2 omission following 15 S1-S2 presentations. These effects were examined at omission and on the following S1-S2 (re-presentation) trial. In Experiment 1 (N = 36), S1 was a 5-sec slide of a snake and S2 was 1 sec of either 65 or 105 dB white noise. The S1-S2 interval was 4 sec. Both frequency and amplitude of omission responses were a positive function of S2 intensity, and responding to S2 re-presentation was reliably higher than on the preomission trial. Experiment 2 (N = 36) used the same S1, an S2 of 105dB, and two additional groups which controlled for stimulus omission and spontaneous recovery. Omission of S2 again produced increased responding to its re-presentation. In Experiment 3 (N = 72), S1 and S2 were moderately intense tones (80dB) and lights (1089 cd/cm². The procedure for the experimental and two control groups was essentially the same as in Experiment 2, except that S1 modality was counterbalanced across subjects. The experimental group displayed significantly larger responses to S2 on the re-presentation trial than the control groups regardless of its modality. The results are discussed in terms of theories of habituation with special emphasis on the concept of priming utilized by Wagner (1976) and Öhman (1979).     

Generalization of Habituation of Skin Conductance Responses to Multidimensional Sequences of Stimuli

This study presents a generalized approach to the problem of habituation to complex sequences of stimuli. Ninety-five subjects were requested to choose one of four cards, showing a blue triangle (BT), a blue square (BS), a red triangle (RT), or a red square (RS). Subjects then heard a prerecorded sequence of the stimulus elements blue (B), red (R), triangle (T), and square (S), in various predetermined orders. Skin conductance responses were recorded during stimulus presentations. Four theoretical models were formulated, and compared for their abilities to describe the habituation process in the present experiment. The models differ in how they define the stimulus categories within which habituation generalizes. The model which defines the stimulus categories by “chosen” versus “non chosen” elements gave the best fit to the data.     

Some Antecedents of Directional Fractionation: Effects of "Intake-Rejection," Verbalization Requirements, and Threat of Shock on Heart Rate and Skin Conductance

Following recent contradictory claims in the literature regarding the phenomenon of directional fractionation, the present study was designed to investigate variables related to this differential patterning of autonomic response. Heart rate (HR) and skin conductance (SC) were recorded from 89 male students who either attended to flashing lights or worked a subtraction problem under threat-of-shock or no-shock conditions. Effects of instructions to verbalize later were also investigated. While significant task differences were demonstrated which were consistent with the directional fractionation hypothesis, instructions to verbalize later affected neither HR nor SC. Threat of shock significantly elevated HR during the task only for Ss attending to flashing lights. However, threat of shock significantly raised HR and SC levels immediately after instructions (and preceding the task) when combined with instructions for subtraction. Results were contrary to arousal theory, supportive of Lacey's theory of an “intake-rejection” dimension, and contrary to Campos and Johnson's verbalization findings.     

Skin Conductance Responses to Stimulus "Energy" Decreases Following Habituation

Two experiments are reported in which a reduction in tone intensity or duration followed habituation. Experiment I, which employed 120 subjects, assessed the effects of type of stimulus change (intensity or duration) and trial of change (trial 5 or trial 22) on orienting response (OR) recovery. Experiment II employed 131 subjects, and examined the effects of reduction of stimulus intensity on trial 22 or after subjects reached a predetermined habituation criterion. Experiment I demonstrated OR reappearance following the offset of a shortened stimulus. The combined findings of Experiments I and II suggest that the effects of reducing stimulus intensity depend on when the change is made. In Experiment I, reducing stimulus intensity on trial 5 led to a significant decrease in OR magnitude. In Experiment II, increases in OR magnitude were produced by reducing stimulus intensity either after reaching a criterion or after 21 habituation trials. These findings suggest a Sokolovian view of the development of the generalization gradient of habituation. Results also revealed large individual differences in responding to the stimulus change in Experiment II. Multiple regression analyses of these data were therefore conducted, which allowed two further conclusions to be drawn: First, initial electrodermal state can be used to predict responding on the stimulus change trial. Second, with long habituation training (21 trials), the role of the initial state variables diminishes while other variables representing change over the experimental session become more prominent in predicting responding to stimulus change.     

The Latency Distribution of the Skin Conductance Response as a Function of the CS-UCS Interval

Latency distributions were obtained for the skin conductance response, by blocks of 5 trials, for groups (N = 13) conditioned with CS-UCS intervals of 3.5, 5.5, 7.5, 10.5, 15.5, and 20.5 sec. Another group (N = 13) received 5, 10, 15, 20, 25, and 30 trials respectively with a .5 sec CS-UCS interval. For all blocks of 5 trials, in the extended CS-UCS groups, the modal response occurred in the 2–3 sec latency range characteristic of the orienting response (OR). There was no significant difference in OR frequency as a function of the CS-UCS interval. There was no systematic increase in response frequency with repeated trials in any of the latency ranges scored. No significant difference in acquisition was obtained as a function of the CS-UCS interval in the extended CS-UCS groups for either frequency or for magnitude. Performance of the (composite) .5 sec CS-UCS group was superior to that of the extended groups. This difference was not attributable to differential OR frequency. The PC group also exhibited a modal response in the 2–3 sec (OR) latency range. Response frequency in the OR latency range was lower in the PC group than in the conditioned groups, but response frequency outside of the OR range was higher in the PC groups than in the conditioned groups.     

Augmenting-Reducing of the Visual Evoked Potential as a Function of Changes in Skin Conductance Level

In the first of two experiments four visual evoked potential (VEP) measures of augmenting-reducing were made consecutively within a single test session on each of 10 student volunteers, on whom palmar skin conductance, taken as an index of arousal, was also monitored continuously. Regression slopes relating VEP amplitude to stimulus intensity for any given individual were found to vary considerably over the session, some subjects changing from augmenting to reducing (or vice versa) during testing. Further analysis of the within-subject data indicated that shifts in augmenting-reducing were related to changes in skin conductance level (SCL) and to the range of SCL over which individuals were operating in relation to the group. Thus, subjects in the high SCL range shifted toward relative reducing as their conductance level increased and those in the low SCL range toward relative augmenting. These effects were exactly replicated in a second experiment using a further 10 subjects and a virtually identical procedure. It was concluded that augmenting-reducing is partly state-dependent, though in a manner which is systematic enough to warrant its further investigation in studies focusing on the dynamic aspects of stimulus modulation.     

Bilateral Skin Conductance and Skin Potential in Schizophrenic and Normal Subjects: The Identification of the Fast Habituator Group of Schizophrenics

Chronic schizophrenics from three different hospitals were compared to normal subjects on skin conductance parameters. In addition to “Responders” and “Nonresponders” as reported by Gruzelier and Venables (1972), a group of “Fast Habituator” schizophrenics was found. These subjects produce one or at most two responses before habituation in an orienting series. The SC waveform of fast habituator subjects shows long latency, slow risetime and long recovery, although the amplitude of response is within normal limits.     

Overextinction of the Evoked Skin Conductance Response: An EEG Study

The present study was designed to investigate Sokolov's (1963) proposal that overextinction of the orienting response (OR) is related to sleep onset. A series of 80 auditory stimuli was presented to 22 male and female Ss. Although re-evocation of the skin conductance response (SCR) component of the OR occurred, in the majority of Ss, after 40–50 stimulus presentations, this was not accompanied by any change in cortical alertness as measured by integrated EEG output in three frequency bands (2–4, 4–8, and 8–13 Hz). However, the results did indicate that Ss displaying SCR return required more stimulus presentations before initial SCR habituation and displayed more spontaneous fluctuations in skin conductance during the prestimulus period than did non-return Ss. Within the return group, latency of SCR return was negatively related to both spontaneous activity during the prestimulus period and number of stimuli to initial habituation.     

Imagery Vividness Affects Habituation Rate

In order to investigate the effect of individual differences in imagery vividness on habituation rate, 14 subjects were threatened with receiving and then imagined receiving an electric shock. Subjects first habituated to a tone which was then used as an auditory signal for the shock threat and the imagined shock. The skin conductance response (SCR) was used to follow the course of habituation. Results demonstrated that subjects with non-vivid imagery habituated to the tone more rapidly than subjects with vivid imagery when the tone was associated with imagining an electric shock. Implications of this finding for therapeutic techniques using instructed imagery are discussed.     

Reaction Time and Heart Rate Between the GET SET and GO of Simulated Races

The results of three experiments are reported in which simulated race situations, i.e., GET SET—5 sec—GO, were used to examine the anticipatory HR response and RT. The first study involved sprinting up a flight of stairs and the second and third a bicycle sprint. The typical pattern of phasic HR found was acceleration until 1 sec prior to GO and then deceleration. Tonic HR appeared to be a function of the degree of anticipated physical effort. Muscle potential, recorded in the first experiment, appeared to he related to HR. No systematic relationship was found between HR and RT.     

Interactive Effects of Stimulus Probability and Significance on the Skin Conductance Response

The present study deals with the effects of stimulus significance and stimulus probability on skin conductance responses (SCRs). Eighty subjects (“informed” group) chose a numbered card, and 60 subjects (“uninformed” group) chose a blank card. All subjects were presented with a series of stimuli in the form of questions about numbers. The relative frequencies of the relevant (chosen) numbers were manipulated. The results showed expected effects of stimulus relevance and stimulus probability on SCRs. A more interesting result was an interaction of stimulus significance and relative frequency, meaning that the probability effect (greater responsivity to the less frequent stimulus) was stronger when the series of stimuli was comprised of relevant and neutral stimuli, than when two different neutral stimuli were used. This latter result was interpreted in terms of generalization of habituation. It was suggested that the relevance manipulation interferes with the generalization of habituation process.     

Effects of Potentially Phobic Conditioned Stimuli on Retention, Reconditioning, and Extinction of the Conditioned Skin Conductance Response

Discriminative classical conditioning of skin conductance responses (SCRs) was studied in 163 college students as a function of four variables: CS type (potentially phobic versus neutral conditioned stimuli), Sex of the subject, Interstimulus interval (ISI) during conditioning (.5 versus 8 s), and Retention interval between conditioning and retention assessment (1 versus 6 months). CS type did not affect acquisition, retention, or reconditioning of the differential conditioned responses. The effect of CS type was highly significant during extinction, with differential SCRs to CS+ and CS- being greater with potentially phobic conditioned stimuli. This was true for both sexes, both the .5-s and the 8-s ISI, and after a 1-month or a 6-month retention interval. Moreover, SCRs conditioned to phobic conditioned stimuli with the .5-s ISI persisted even after subjects' cognitive expectancy of the UCS, which was measured on a trial-by-trial basis, had completely extinguished. The results indicate that the effect of potentially phobic conditioned stimuli on the conditioned skin conductance response is unique to resistance to extinction-they affect not learning but unlearning of the autonomic response.