Electrodermal Reactions Research Articles

Standardization of infrasounds and low-frequency noises for health benefits on humans

Annoyances from low-frequency noises and infrasound are effects of using technologies, transportation, manufacturing equipment, and large air-condition systems. Present developed procedures for evaluations of annoyance of low-frequency noise (LFN) on humans and occupational health are based on international and national standards. Comparisons show that there is a large difference between permitted values of acoustic pressure levels used. These standards are based on levels of thresholds heard by the human auditory system and subjective observations of impacts from vibrations of infrasound waves on the human body. A newly discovered phenomenon shows a follow-up effect in the brain and is an important reason to check and investigate attenuation of infrasound, especially near and below 10 Hz. Previous investigations showed that nonlinear reaction is observed according to the external infrasound field pressure on the human body. New studies need to investigate electrical reactions of the human brain and electrodermal reactions by influences of infrasound. [Work supported by the Kosciuszko Foundation, Inc., an American Center for Polish Culture, with Funding provided by the Alfred Juzykowski Foundation and KBN Warsaw.]

Automatic checkout systems to monitor driver's vigilance.

A concept for designing automatic checkout systems to prevent drivers from falling asleep is presented. It is shown that such systems should use the frequency of electrodermal reactions (EDR), which is governed by changes in skin resistance. Such changes have a time constant of several seconds. To detect these reactions, a special technique was developed. Experimental investigations yielded the quantitative characteristics of EDR changes associated with decreased vigilance. It was found that, when a person started to fall asleep, the EDR frequency diminished. An EDR-based system was developed to assess the alertness level. Such a system may be employed to prevent drivers from falling asleep.

Sex differences in electrodermal activity in wakefulness of a different level

Electrodermal activity or skin galvanic response (changes in skin electrical resistance [1-3]) is one of the best-known electrophysiological phenomena widely used in psychophysiological studies and practice. This activity can be differentiated into a tonic component with the time constant of several minutes and a phasic electrodermal reaction (EDR) with the time constant of several seconds. The latter is associated with an orienting reflex and appears either in response to a stimulus or without evident stimulation (nonspecific or spontaneous EDRs). However, after the reliability of electrodermal indices was questioned [4], they are less frequently used. Many studies have reported the presence of sex differences in some electrodermal parameters [5-15], but some others found no such differences [ 16-18]. This discrepancy can be explained by differences in both analyzed indices and experimental procedures [3].

Affective reactions to acoustic stimuli

Emotional reactions to naturally occurring sounds (e.g., screams, erotica, bombs, etc.) were investigated in two studies. In Experiment 1, subjects rated the pleasure and arousal elicited when listening to each of 60 sounds, followed by an incidental free recall task. The shape of the two-dimensional affective space defined by the mean ratings for each sound was similar to that previously obtained for pictures, and, like memory for pictures, free recall was highest for emotionally arousing stimuli. In Experiment 2, autonomic and facial electromyographic (EMG) activity were recorded while a new group of subjects listened to the same set of sounds; the startle reflex was measured using visual probes. Listening to unpleasant sounds resulted in larger startle reflexes, more corrugator EMG activity, and larger heart rate deceleration compared with listening to pleasant sounds. Electrodermal reactions were larger for emotionally arousing than for neutral materials. Taken together, the data suggest that acoustic cues activate the appetitive and defensive motivational circuits underlying emotional expression in ways similar to pictures.

The hypothesis of the nature of electrodermal reactions

Long-term studies of electrodermal activity (EDA) in the activation-relaxation cycles, including simultaneous recording of skin resistance and temperature, were conducted. The new facts observed (a rapid drop in conductance after electrodermal response (EDR), a frequent absence of a correlation between skin resistance and EDR frequency, the conditions for correlation between the dynamics of resistance and temperature) are difficult to explain within the framework of the most generally accepted hypothesis of the formation of all EDA components by the secretory region of the eccrine sweat glands. They testify in favor of the hypothesis of the existence of two systems of EDA regulation that are largely independent. According to the hypothesis, the thermoregulation function is mainly mediated by the continuous release of a secretion resulting in tonic changes in resistance. EDR occur in response to emotions and are associated with thermoregulation, but only slightly. They are determined by the properties of the excretory region of the gland. The phase of decrease in resistance is accompanied by narrowing of the ducts caused by myoepithelial cells on activation, possibly adrenergic, of the sympathetic nervous system.

Comparison of electrodermal constant voltage and constant current recording techniques using the phase angle between alternating voltage and current

If electrodermal activity is recorded with direct current, constant voltage and constant current measurements result in different dependencies of electrodermal reactions on the actual electrodermal level. The present study demonstrates empirically that such a problem does not exist when instead the phase angle changes between alternating current and voltage are obtained. Forty subjects were subjected to a 20-trial habituation series on two different occasions, in which electrodermal level variations were induced by room temperature changes. A multiplexing system was used to enable quasi-simultaneous constant current and constant voltage recording under both direct and alternating current measurement conditions. If the alternating current technique was applied and electrodermal responses were expressed as changes of phase angle between voltage and current, electrodermal recordings with constant voltage and with constant current provided equivalent results, even if electrodermal levels were considerably different. Therefore, using the phase angle method instead of the conventional direct current methods will finally resolve the problem of differential level dependency in electrodermal recording. A further advantage will be that electrode and skin polarization are prevented by the use of alternating current.

Comparison of electrodermal constant voltage and constant current recording techniques using the phase angle between alternating voltage and current

If electrodermal activity is recorded with direct current, constant voltage and constant current measurements result in different dependencies of electrodermal reactions on the actual electrodermal level. The present study demonstrates empirically that such a problem does not exist when instead the phase angle changes between alternating current and voltage are obtained. Forty subjects were subjected to a 20-trial habituation series on two different occasions, in which electrodermal level variations were induced by room temperature changes. A multiplexing system was used to enable quasi-simultaneous constant current and constant voltage recording under both direct and alternating current measurement conditions. If the alternating current technique was applied and electrodermal responses were expressed as changes of phase angle between voltage and current, electrodermal recordings with constant voltage and with constant current provided equivalent results, even if electrodermal levels were considerably different. Therefore, using the phase angle method instead of the conventional direct current methods will finally resolve the problem of differential level dependency in electrodermal recording. A further advantage will be that electrode and skin polarization are prevented by the use of alternating current.

707 The peculiarities of electrodermal reactions accompanying the changes of alertness in humans

Three experiments were run revealing that peripheral cues exert an alerting and orienting effect. Novel is the finding that peripheral cues induce a (hidden) tendency to respond to the cued side, which interacts with the response tendency elicited by the subsequent following target. Compatible S-R mappings revealed either a reversed or no response tendency in cue conditions as compared to uncued conditions. Incompatible mappings mostly showed a decrease in response tendencies under influence of the peripheral cue. An increase of the interval between the cue and the target up to 500 ms resulted in a return to the baseline condition (without cue). The findings for the compatible mappings may be interpreted in terms of an extra recoding operation that was induced by peripheral cues. Inconsistencies found for incompatible S-R mappings might be attributed to the dual presence of recoding operations on account of the cue and the target.

705 Hypothesis about the nature of electrodermal reactions

This paper focussed on how electrophysiological autonomic data may contribute to better understand neural substrates of emotional processing. The utility of autonomic electrophysiological markers for assessing emotional and cognitive processes is presented in the context of an important bodily arousal interface. Components of general autonomic control are reviewed and relevant neural modulations of specific autonomic variables were discussed. The role of autonomic feedback on central processes is emphasized and neural influences on autonomic activities as an index of arousal dimension, the electrodermal activity (EDA), are outlined. An overview of brain mechanisms governing generation and control of EDA is presented, and the contribution of electrodermal parameters as indices of emotional activation illustrated by data related to diurnal emotional reactivity and to non consciously subjective emotionality. Conclusions highlight the role of electrical autonomic expressions as tools to explore emotional components of mind-body-mind relationships.

Jealousy, general creativity, and coping with social frustration during the menstrual cycle.

Sensitivity to feelings of jealousy in women (n = 16) at three phases of their menstrual cycle differing in serum hormone concentrations (menses, preovulatory phase, midluteal phase) was investigated. Nonspecific electrodermal activity indicating sympathetic excitation was measured while subjects listened to stories and imagined situations inducing (i) nonsexual jealousy (the partner forms a deep emotional attachment to another woman), (ii) sexual jealousy (the partner has sexual intercourse with another woman), and (iii) no jealousy (social interaction lacking intense emotionality). Subjective ratings of the intensity of jealousy during both stories of jealousy were also assessed. In addition, changes in cognitive coping abilities, in general, and in the context of socially frustrating events, were assessed by tests of divergent thinking (creativity) and the Rosenzweig Picture Frustration Test. Frequency of nonspecific electrodermal reactions was generally enhanced during the preovulatory phase. This increase was particularly strong when the women listened to stories inducing nonsexual jealousy, i.e., a story characterized by cues of a complete loss of the partner's investment. Rated jealousy tended to be enhanced during the ovulatory phase, especially after the story of nonsexual jealousy. These changes in emotionality were paralleled by an improved divergent thinking performance and less aggressive coping with socially frustrating events around the time of ovulation.

Electrodermal and subjective reactions to fear-relevant stimuli under threat of shock

Three experiments investigated normal subjects' reactions to pictures of fear‐relevant stimuli (snakes, spiders, guns) and control stimuli (e.g., flowers, rabbits) under threat of electric shock. First‐interval electrodermal responses (FTRs) and shock expectancy ratings were recorded. Experiment 1 demonstrated larger FTRs and expectancy ratings to fear‐relevant stimuli, with and without threat of electric shock. In Experiment 2, trait anxious subjects showed elevated expectancy ratings that were additive with the bias associated with fear‐relevant stimuli. Experiment 3 demonstrated that reactions to fear‐relevant stimuli were not an artefact of the expectancy rating task. There were no substantial differences between biological and technological fear‐relevant stimuli. Overall, the experiments confirm that fear‐relevant stimuli elicit larger reactions in the absence of any specific manipulation, such as conditioning. The results are most consistent with cognitive models that emphasise learning rather than genetic factors, and that attribute electrodermal reactions to elevated expectancy of aversive events.

Effect of intertrial intervals on recovery and amplitude of electrodermal reactions

Convincing findings have been published about the importance of prior activity on electrodermal recovery. However, these studies mainly used tone tasks as an experimental paradigm. The present research investigated the influence of prior activity by changing the intertrial intervals (ITI) in cognitive and reaction time tasks. Results indicated that ITI had no effect on amplitude but had a significant effect on recovery time, a longer ITI period producing a longer recovery curve. No correlation was found between recovery and amplitude. Analysis also indicated that variable intervals should not be recommended between the tasks. These observations emphasize the importance of prior activity on electrodermal recovery in more complex tasks.

Continuous recordings of impedance and phase angle during electrodermal reactions and the locus of impedance change.

The relatively few studies that use alternating current (AC) in exosomatic electrodermal recording techniques focus on tonic measurement but not on phasic measures. AC methods of phasic measurement, however, are most useful in testing electrical models of the electrodermal response. Problems arising from AC recording of fast electrodermal changes are discussed, and an appropriate measurement concept for continuous recording of impedance and phase angle is developed. This enables tonic values of both parameters to be offset in order to sufficiently amplify small changes. An AC frequency of 100 Hz was used in recording electrodermal activity in 10 subjects during an habituation series of 80dB 1000 Hz tones. Comparison of transformed curves showed that the main component of electrical changes accompanying electrodermal response is a shift in conductance while susceptance shows only small fluctuations. According to a widely accepted simple electrical model of skin, these results indicate that electrodermal responses take place mainly in the resistive element which parallels the capacitance associated with the stratum corneum, but that other components may be involved too.

Psychometrische En Elektrodermale Aspecten Van Het Illusionaire Correlatie-Fenomeen: Enkele Paradoxale Gegevens

[Psychometric and Electrodermal Aspects of Illusory Correlations: Paradoxal Results] Recent studies by Mincka and Tomarken (1989) show that high-fear subjects tend to overestimate the covariation of fear-relevant stimuli and aversive outcomes, i.e., report an illusory correlation. These authors suggest that illusory correlations play a crucial role in the etiology and maintenance of anxiety disorders. Yet, the fact that high-fear subjects report illusory correlations does not necessarily imply that illusory correlations predispose to or maintain anxiety. To clarify this issue, an experiment (N = 24) was carried out in which normal, unselected subjects were confronted with a quasi-random series of three types of stimuli (snake or spider, mushroom, and flower). Stimuli were followed an equal number of times by three types of outcomes (tone, electric shock, nothing). Electrodermal reactions (SCRs) to the stimuli were recorded trough-out the experiment which contained 27 trials. Post hoc, subjects were asked to give conditional probability-estimates of all stimulus/outcome combinations. Two groups were then formed. One group (n = 10) consisted of subjects who reported an illusory correlation. The second group (n = 14) consisted of the remaining subjects. The illusory correlation-group displayed an overestimation only for the snake (spider)/shock association. Surprisingly enough, subjects in this group had significantly lower FQ scores and tended to have lower SCRs to snakes (spiders) than control subjects. It is hypothesized that the association between anxiety and illusory correlation is either positive or negative depending on the number of trials, with a small number of trials resulting in a negative association (due to hypervigilance of high-fear subjects) and a large number of trials resulting in a positive association (due to strong apriori judgments of these subjects). Alternative interpretations of the present pattern of results are discussed.

Interpretation of homophones related to threat in anxiety states.

In previous studies, we have established that anxiety states are characterized by an attentional bias that favors the processing of threatening stimuli. In the present study we extend this finding to ambiguous stimuli, specifically, homophones with spellings that correspond to either a threatening or a neutral meaning. As predicted, clinically anxious subjects used the threatening spellings relatively more than did controls, whereas recovered subjects were intermediate in this respect. Threatening words were associated with greater skin conductance responses than were neutral words, but the groups did not differ in their electrodermal reactions to homophones. We take these findings as evidence that, although the different meanings of ambiguous stimuli may be processed in parallel by all subjects, an interpretive bias operates such that anxiety-prone individuals tend to become preferentially aware of the more threatening meaning of such events.

Are stress responses influenced by cognitive appraisal? An experimental comparison of coping strategies.

An investigation of the role of cognitive appraisal in emotional responses was carried out, in which psychological and physiological reactions to a distressing film were recorded in three groups of volunteers. Subjects in the intellectualization condition were given instructions to appraise the film in a detached, analytic fashion. The sensation-focusing group were asked to focus on physical sensations and to experience them fully, and controls were given no specific instructions. Heart rate, skin conductance and respiration rate were monitored continuously, while ratings of psychological distress and physical sensations were collected periodically. No significant differences were found in the subjective or physiological reactions of the intellectualization and control groups, thus failing to replicate previous reports. Sensation focusing led to a diminution of cardiac and electrodermal reactions, but did not affect subjective experience. Limitations to the concept of cognitive appraisal are suggested, while explanations of the results are offered in terms of external vs. internal deployment of attention, and desynchrony of emotional responses.

Moderating Effects of Trait Anxiety on Electrodermal Reactions in Different Learning Conditions

This study examined the control of the effects of trait anxiety on GSR during a problem-solving task under different conditions. Of 84 subjects, 39 men and 49 women of mean age 21 yr., 42 were classified as high in anxiety, 42 as low in anxiety. Subjects solved concept-formation tasks at different degrees of difficulty under one of three learning conditions. Low tone, unpleasant loud tone, and unpleasant electric shock provided the three kinds of error feedback. For the ‘low tone’ and ‘electric shock’ as feedback on errors significant differences in GSR values resulted for groups high and low in anxiety with the latter showing higher scores. The relevance of physiological patterns in multidimensional activation theories for research on anxiety is discussed.

Biofeedback-assisted relaxation in the control of reactions to a challenging task and anxiety-provoking film

This experiment was designed to evaluate the use of a combined relaxation- and biofeed-back-training procedure in the regulation of psychophysiological reactivity to laboratory stressors. Twenty volunteers participated in the 3-session experiment, comparing relaxation plus skin conductance biofeedback (Training) with simple instructions to relax (Control). During Session 1. subjects tried to solve a series of visual puzzles and watched an anxiety-provoking film, and were then assigned to treatments on the basis of electrodermal reactions to the film. The relaxation methods were practised in Sessions 2 and 3. and were followed by a second film excerpt and series of tasks. Heart rate (HR), skin conductance level (SCL) and ratings of tension and relaxation were recorded throughout. No differences in physiological or self-report variables emerged during quiet relaxation. However, during the post-treatment administration of Stressors, SCL was augmented in the Control group, while remaining near pre-treatment values in the Training condition. This effect was confined to SCL, since HR and self-reported tension did not distinguish the groups post-treatment.

Voluntary control of cardiovascular reactions to demanding tasks

Three groups of 10 normotensives participated in a study exploring voluntary control of cardiovascular reactions to cognitive tasks. Pulse transit time (TT), interbeat interval (IBI), skin conductance level, and respiratory variables were monitored throughout one introductory and four experimental sessions. The groups were matched on the basis of initial TT and IBI responses to the taxing arithmetic and reasoning tasks. During experimental sessions, one group (FB) was provided with visual analogue TT feedback, while the REL group was given detailed relaxation instructions. A third group (CON) performed the same sequence of tasks but was not instructed to modify cardiovascular reactions at any point. Training in voluntary control was carried out in resting (no-task) conditions, and during task administration. Both treatment groups showed lower cardiovascular reactions than controls in task trials. Only REL subjects lengthened TT in no-task conditions, while both FB and REL groups showed smaller cardiovascular reactions than CON during the tasks. Effects were confined to cardiovascular variables, since respiratory and electrodermal reactions during task administration were similar in all groups. The effects of treatments were especially marked among the most reactive subjects.

Electrodermal reactions to opposite types of autogenic training imagery

An experiment was conducted to determine the effects of autogenic and ‘opposite autogenic’ verbal formulae upon electrodermal activity. In a between-subjects design, 15 unpracticed volunteers listened to and followed tape recorded imagery suggestions for relaxation and quietude, heaviness and warmth in the extremities, warmth in the central area of the body, coolness of the forehead, and calmness and regularity of breathing and circulation; 15 additional volunteers were exposed to opposite suggestions. Frequency of spontaneous GSRs, cumulative peak amplitude of spontaneous GSRs, and basal skin resistance levels were measured during 2 min epochs before and after the suggestions. Directionally appropriate changes occurred in all three electrodermal measures; these changes were significant for the two GSR measures and approached significance for the BSR measure. The autogenic suggestions produced greater and more reliable visceral effects than did the ‘opposite autogenic’ suggestions.