Bilateral Asymmetry of Skin Conductance Responses During Auditory and Visual Tasks

Bilateral skin conductance (SC) was recorded while dextral subjects engaged in tasks designed to differentially engage the right (RH) and left (LH) hemispheres. Subjects compared strings of speech sounds (LH) and musical chords (RH). They also decided whether written words rhymed (LH) and viewed pictures of faces in a continuous recognition paradigm (RH). SCRs in the right hand were larger during the chords task than the syllables task. The left hand did not differ for the two stimuli. In the visual experiment a comparable effect was obtained in males only. SCRs in the left hand were larger for rhymes than faces; the right hand did not differentiate between stimuli. Sex differences in laterality are considered. Subjects who were more equally balanced in awareness of the two sides of their bodies and subjects with familial sinistrals were more likely to show task appropriate SC changes. Using rote repetition and visual imagery as mnemonics did not affect SC asymmetries.     

Effects of Cigarette Smoking on Bilateral Electrodermal Measures of the Orienting Reflex

Bilateral skin conductance was recorded in 6 male and 6 female smokers and in 6 male and 6 female nonsmokers on two different days. On the first day, a 10-min rest period during which 3 male and 3 female smokers smoked a cigarette was followed by a taped series of common and uncommon innocuous tone stimuli to which evoked responses were measured. Nonsmokers did not smoke prior to presentation of the tones. On the second day, one week later, evoked responding was again measured during two further presentations of the tone stimuli after a 10-min rest period during which the remaining smokers smoked a cigarette. During the first presentation, subjects listened to the tones as before. During the second presentation, subjects performed a pedal-press whenever they heard the uncommon tone in the series. Results showed that smoking depressed responding to common and uncommon tones on the first day, but elevated responding to both tones on the second day during the passive listening phase. During the pedal-press task, smoking selectively elevated responding to uncommon tones. Male smokers gave larger responses to uncommon tones in their left than right hands during the pedal-press task, especially after smoking. Results are interpreted in terms of nicotine-induced enhancement of the voluntary orienting reflex possibly mediated by the left frontal cortex.     

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.     

The Effect of Stimulus Significance on Skin Conductance Recovery

The relationship between skin conductance (SC) recovery time and stimulus meaning was investigated. Previous research has shown that a strong relationship between prestimulus electrodermal activity (prior activity) and recovery time makes it necessary to control prior activity before the relationship of recovery time and stimulus meaning can be evaluated properly. In this study prior activity was controlled by experimental design. We examined the effects of stimulus meaning on skin conductance recovery time and amplitude in 55 teenage and young adult subjects in a continuous performance paradigm. Tones were presented monaurally to left and right ears. Subjects were required to make a pedal press after any tone in the left or right ear that followed a right-ear tone. Recovery time was computed for left-ear and right-ear tones not requiring a press because they had been preceded by a left-ear tone. SC recovery was longer for signal (right-ear) than for nonsignal (left-ear) tones with the effects of prior SC activity and amplitude removed. These findings replicate those of a pilot study (Janes, 1982). We conclude that stimulus significance can affect SC recovery time and that in this paradigm differences in prior SC activity cannot account for the recovery time differences observed.     

Arousing and De-Arousing Effects of Cigarette Smoking Under Conditions of Stress and Mild Sensory Isolation

The arousing and de-arousing effects of smoking a 1.3 mg nicotine delivery cigarette, measured by changes in electrodermal, heart rate and EEG alpha responding, were examined under conditions of stress, induced by aversive white noise, and mild sensory isolation. Compared with sham smokers and a situation control group, smokers showed significant arousal elevations in all response systems under sensory isolation conditions, but mixed stimulant (heart rate response) and depressant (EEG, skin conductance response) effects under stress conditions. Possible reasons for these differential effects are suggested.     

Skin Conductance Responses in Huntington's Chorea Progeny

To test the assumption that limbic dysfunctioning in Huntington's Chorea (HC) would be reflected in abnormal skin conductance responses, 25 patients were examined.Only 2 of these patient showed normal skin conductance response. A further sample of 52 first generation, asymptomatic offspring of diagnosed HC patentes were tested. Seventeen of the at-risk subject were non-responders compared with 2 non-responders in the control sample of 26 subjects. The finding could be interpreted to favor the hypothesis that the presence of the pathogenic gene is correlated with electrodermal non-responding.     

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.     

Effects of Stimulus Omission and Stimulus Novelty on Dishabituation of the Skin Conductance Response

The present experiment (N=64) examined the effects of stimulus omission and stimulus novelty on dishabituation of the skin conductance response. During the training phase, subjects received 15 S1-S2 pairings. On trial 16, S2 was omitted for one group, replaced by an experimentally-novel stimulus for a second, and replaced by an experimentally-familiar stimulus for a third. The control group simply received a further S1–S2 pairing on trial 16. All groups received a further S1–S2 pairing on trial 17. Tone, white noise, light, and vibration served equally often as experimental events, and responses to S1 and to S2 on trial 17 constituted the data of primary interest. The data indicated that both stimulus omission and stimulus novelty on trial 16 produced dishabituation to S2 on trial 17, whereas presentation in an unexpected position of an experimentally-familiar stimulus did not. The results are discussed in terms of the concept of priming.     

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.     

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.     

The Status of Skin Conductance Recovery Time: An Examination of the Bundy Effect

The independent status of recovery of the skin conductance response has been an important assumption underlying work in which electrodermal responses to different task demands have been examined or in studies in which different psychopathological groups have been differentiated. Doubts on this issue have recently been raised by Bundy and Fitzgerald (1975). The present study examines data on this point from two samples and suggests that it is still worthwhile to treat SCR recovery as an independent variable.     

Stimulus Site Effects on Skin Conductance Responses From the Volar Surfaces

Pulse trains were applied separately to each forefinger and to each hallux of 23 Ss to assess stimulus site effects on the relative amplitudes of skin conductance responses recorded concurrently from each palm and from each plantar surface. A binaurally presented tone was used as a non-lateralized stimulus. Analyses of the ratio of response amplitudes from contralateral recording sites indicated that for both the upper and lower extremities, responses from the volar surface of the stimulated extremity were augmented in amplitude. Responses from the volar surface of the extremity ipsilateral to the stimulus and recording sites involved the same extremity. Analyses of the ratio of response amplitudes from the palmar and plantar surfaces on the same side of the body indicated that the specific effects of stimulation did not cross the body midline. The results were interpreted as indicating a regionally differentiated sympathetic outflow to the volar sweat glands that reflects the locus of cutaneous stimulation.     

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).     

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.     

The Relationship Between Skin Conductance Orienting the Allocation of Processing Resources

Information processing models of autonomic orienting suggest that the elicitation of an orienting response is associated with either the call for, or the actual allocation of, limited attentional processing resources. However, Dawson, Filion, and Schell (1989) reported a directional dissociation between elicitation of the skin conductance orienting response and resource allocation, as indexed by reaction time slowing on a secondary task. Although larger skin conductance responses were elicited by a task-relevant stimulus than by a task-irrelevant stimulus, reaction time showed the opposite pattern (i.e., greater slowing to secondary task probes presented shortly following the onset of the task-irrelevant stimulus). In the present report, we describe three experiments which examine the generality of this dissociation effect and test specific hypotheses regarding its nature. Results of the first two experiments revealed that the dissociation effect is observed reliably when the task-relevant and task-irrelevant stimuli consist of left ear and right ear tones or high and low pitched binaural tones, across a range of secondary task probe presentation times. However, the third experiment demonstrated that when task-relevant and task-irrelevant stimuli are presented to different sensory modalities (auditory and visual), orienting and resource allocation are both greater during the task-relevant than the task-irrelevant stimuli, thus eliminating the dissociation effect. These results support the hypothesis that the dissociation effect is due to a switch of attention initiated because of the physical similarity of the task-relevant and task-irrelevant stimuli, and suggest that there is a fundamentally positive relationship between skin conductance orienting and resource allocation under selective attention conditions.     

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.     

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.     

Active Circuits for Direct Linear Measurement of Skin Resistance and Conductance

Passive voltage-divider circuitries typically used for measuring skin resistance and conductance provide only indirect measures of these variables. Although the resulting errors of nonlinearity may not be critical for some research purposes, there is no reason why they should be tolerated, because it is possible to design simple active circuitry which avoids the errors by measuring skin resistance and conductance directly. Two such circuits are presented: a) a variable-gain voltage amplifier for direct linear measurement of skin resistance; and b) a current-to-voltage transducer for direct linear measurement of skin conductance. A combined working circuit, suitable for practical research applications, is also presented.     

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).