Electrodermal Activity Responses Research Articles

P03-425 - Electrodermal activity in response to a set of mental tasks in caregivers of persons with autism spectrum disorders

IntroductionAnalysing reactivity to laboratory stressor in lab is a valid model for understanding how people act in real-life situations. Electrodermal activity is a good index of emotionality, which has not been analysed in caregivers of persons with Autism Spectrum Disorders (ASDs).Objectives and aimsThis work aims to compare the response of electrodermal activity to mental stress between caregivers of ASDs people and controls, as the former could show a different response due to their particular situation characterised by a state of continuous alert.MethodsParents of both genders of people with (n = 44) or without (n = 42) ASDs carried out a set of different mental tasks. Skin Conductance Level (SCL) was continuously registered before, during, and after the tasks. Skin Conductance Responses (SCR) were obtained from SCL levels using Acqknowledge software.ResultsFor SCL, a significant effect of “gender” and of “period x group” and “period x group x gender” interactions was observed. SCL was higher in men than in women and in controls when compared to caregivers. Controls presented more SCL Reactivity than caregivers, being these results were replicated in men (who also showed worse recovery in controls) but not in women. In caregivers, men showed lower SCR Reactivity than women.ConclusionsCaregivers of ASDs showed a lower electrodermal reactivity to mental stress than controls, and this effect was stronger in men. These results could reflect a lower reactivity to stressful situations in caregivers and, consequently, a loss of the adaptative potential of the stress response in this population.

Electrodermal activity in response to empathic statements in clinical interviews with fibromyalgia patients

Objective To study patients’ electrodermal response (1) to an interviewer's empathic statements vs. inattention to emotional concerns and (2) to the emotional content in clinical interviews. Methods Patients with fibromyalgia ( n = 48) were given a clinical interview in a randomized 2 × 2 design, in which interviewer empathic or inattentive behavior (scenario A) and the emotional or neutral content of the interview (scenario B) were manipulated. Electrodermal activity (EDA) was measured during the interview. The patients’ affective state (PANAS) and patient satisfaction were also assessed. Results In scenario A a significant main effect of empathy was found, indicating an increased tonic EDA (skin conduction level, SCL) during the empathy condition ( p < .05). In scenario B there was a main effect of empathy ( p < .01) and a significant empathy × content interaction effect ( p < .01). There was a strong positive association between empathy and patient satisfaction ( p < .0001). Conclusions Empathic statements by the interviewer were associated with increased SCL in patients, most so in interviews with emotional content. Practice implications Psychophysiological variables such as EDA may be applied in clinical communication research on emotional communication, but the limitations of such measures should also be recognized.

Electrodermal complexity during the Stroop Colour Word Test

Several recent studies suggest that quantitative description of signal complexity using algorithms of nonlinear analysis could uncover new information about the autonomic system that is not reflected using common methods applied to measures of autonomic activity. With this aim we have performed complexity analysis of electrodermal activity (EDA) assessed in 106 healthy university students during rest conditions and non-conflicting and conflicting Stroop task. Complexity analysis applied to EDA was performed using Skinner's algorithm for pointwise correlation dimension (PD2). Results have shown that EDA responses during the Stroop Colour Word test are related to significantly increased or decreased complexity. Particularly significant result is that PD2 has a unique ability to predict to an extent the change in EDA response to stress i.e. that subjects with low initial PD2 tended to respond to experimental stress by its increase and subjects with high initial PD2 values tended to respond by its decrease. This response was not found in EDA measures where increase of the EDA presented predominant response to experimental stress in majority of the subjects. These findings suggest that PD2 is more sensitive to subtle aspects of functionally and spatially distributed modulatory influences of various parts of the brain that are involved in the EDA modulation and provides novel information in comparison to traditional methods.

Brain activation patterns underlying fast habituation to painful laser stimuli

A painful experience is modified by processes like habituation/antinociception or sensitization. Altered habituation may be one characteristic of chronic pain syndromes. In the present study we sought to investigate the functional magnetic resonance imaging (fMRI) blood oxygen level dependent (BOLD) correlate of rapid habituation to pain using simultaneous single trial electrodermal activity (EDA)/fMRI measurements. A total of N = 32 healthy subjects have been investigated. Subjects received painful laser stimulation of the left hand. The fMRI BOLD response was measured simultaneously with continuous EDA recordings. Single trial EDA responses to laser stimulation habituated over time with substantial subject-to-subject differences in the degree and speed of habituation. fMRI BOLD habituation was assessed by contrasting the first half of the experiment against the second half and was found in primary and secondary somatosensory cortices, the insula and the anterior cingulate cortex (ACC). We hypothesized that single trial EDA habituation would reflect BOLD habituation which was investigated separately in subjects with ‘faster’ ( N = 15) and ‘slower’ ( N = 14) EDA habituation. Significant habituation of the BOLD signal was only found in subjects with ‘faster’ EDA habituation that was accompanied by a signal increase in the rostral ACC and the periaqueductal grey. Furthermore, subjects with faster EDA habituation provided lower pain ratings. Therefore the EDA habituation profile to painful stimulation may constitute a pain-related (endo)phenotype and may be an informative additional endpoint measure in fMR-imaging of pain, especially when people suffering from chronic pain states in which pain processing is often altered are studied.

Sequential unfolding of novelty and pleasantness appraisals of odors: Evidence from facial electromyography and autonomic reactions.

We investigated the effects of odors on appraisal processes and consequent emotional responses. The main goal was to test whether an odor is detected as novel or familiar before it is evaluated as pleasant or unpleasant. Participants performed a recognition task in which they were presented with pairs of unpleasant or pleasant odors (sample and target odors). Within a pair, the sample and target were either identical or different to assess participants' novelty detection; unpleasant and pleasant target odors were contrasted to examine participants' appraisal of intrinsic pleasantness. We measured facial expressions using electromyography and physiological reactions using electrocardiogram and electrodermal activity in response to odors. The earliest effects on facial muscles and heart rate occurred in response to novelty detection. Later effects on facial muscles and heart rate were related to pleasantness evaluation. This study is the first to demonstrate the existence of a sequence of appraisal checks for odors eliciting emotional reaction.

Fluctuations in electrodermal activity reveal variations in single trial brain responses to painful laser stimuli — A fMRI/EEG study

Pain is a complex experience with sensory, emotional and cognitive aspects. It also includes a sympathetic response that can be captured by measuring the electrodermal activity (EDA). The present study was performed to investigate which brain areas are associated with sympathetic activation in experimental pain; an issue that has not been addressed with fMRI (functional magnetic resonance imaging) thus far. Twelve healthy subjects received painful laser stimulation to the left hand. The event-related fMRI BOLD (blood oxygen level dependent) response was measured together with simultaneous EEG (electroencephalography) and EDA recordings. Laser stimuli induced the expected EDA response, evoked EEG potentials and BOLD responses. Single trial EDA amplitudes were used to guide further analysis of fMRI and EEG data. We found significantly higher BOLD responses in trials with high EDA vs. low EDA trials, predominantly in the insula and somatosensory cortex (S1/S2). Likewise, in the EEG we found the N2 laser evoked potentials to have significantly higher amplitudes in trials with high vs. low EDA. Furthermore EDA-informed BOLD modeling explained additional signal variance in sensory areas and yielded higher group level activation. We conclude that the sympathetic response to pain is associated with activation in pain-processing brain regions, predominantly in sensory areas and that single trial (EDA)-information can add to BOLD modeling by taking some of the response variability across trials and subjects into account. Thus, EDA is a useful additional, objective index when pain is studied with fMRI/EEG which might be of particular relevance in the context of genetic- and pharmacoimaging.

Separating deceptive and orienting components in a Concealed Information Test

The Concealed Information Test (CIT) requires the examinee to deceptively deny recognition of known stimuli and to truthfully deny recognition of unknown stimuli. Because deception and orienting are typically coupled, it is unclear how exactly these sub-processes affect the physiological responses measured in the CIT. The present study aimed at separating the effects of deception from those of orienting. In a mock-crime study, using a modified CIT, thirty-six of seventy-two subjects answered truthfully (‘truth group’), whereas the other thirty-six concealed their knowledge (‘lie group’). Answering was delayed for 4 s after item presentation. Electrodermal activity (EDA), respiration (RLL), and phasic heart rate (HR) were recorded. A decomposition of EDA responses revealed two response components; the response in the first interval was expected to indicate orienting, stimulus evaluation, and answer preparation, whereas the response in the second interval was assumed to reflect answer-related processes. Inconclusively, both EDA components differentiated between ‘probe’ and ‘irrelevant’ items in both groups. Phasic HR and RLL differed between item classes only in the ‘lie’ group, thus reflecting answer-related processes, possibly deception, rather than merely orienting responses. The findings further support the notion that psychophysiological measures elicited by a modified CIT may reflect different mental processes involved in orienting and deception.

Examining the influence of fame in the presence of beauty: an electrodermal ‘neuromarketing’ study

Abstract The use of famous and/or attractive models in brand marketing is ubiquitous yet little work, if any, has been carried out examining differences in their efficiency in driving subsequent consumer behaviour. Such brand platforms have an emotional selling proposition (ESP) that refers to the unique personality and image attributes that a particular endorsement generates. However, celebrity endorsers are also more than likely to be considered attractive and thus differences in the ESP (if any) would be very small. Such differences in an emotional response could be measured by a participant's electrodermal activity (EDA). This is a psychophysiological response, measurement of which is sensitive enough to detect differences engendered by a particular brand platform's ESP. In the present study, EDA measurements were recorded from participants who were shown advertisements containing a target product within four different types of endorsement platforms depicting models who were either famous/non‐famous or attractive/average looking. The results showed that average looking celebrity endorsers produced a greater EDA response than any of the other conditions including the attractive looking celebrity endorsers. Furthermore, this effect was only revealed from recordings taken from the left hand side of the participants. Given that the right side of the brain would orchestrate any EDA responses recorded from the subjects' left side, the current results suggest a dedicated neural response for celebrity endorsed brand platforms. Future work examining the relationship between the specific EDA signature and consumer preferences is discussed. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Electrodermal activity as a possible physiological marker for acupuncture

Change in amplitude of skin potential is one of the physiological indicators of electrodermal activity (EDA) and has been associated with the onset of a variety of sensory, cognitive and emotional stimuli. This study investigated the EDA physiological response to manual acupuncture. A group of 60 healthy female volunteers were recruited into the study of which 30 were randomly assigned to a control group (no acupuncture) and 30 to the experimental group (received acupuncture). The experimental group attended three sessions in which acupuncture intervention consisting of unilateral manual stimulation of acupuncture points LU7 and KD6. Results showed that the insertion, stimulation and withdrawal of the acupuncture needles were associated with significant changes in EDA. The insertion of the needle was associated with the highest change in skin potential while the three consecutive manipulations of the needles showed a decline in EDA amplitude, thought to be consistent with physiological habituation. Anxiety level and previous familiarity with acupuncture did not influence outcomes. It is postulated that the change in EDA during needle insertion is non-specific to the type and the function of acupuncture points; however, EDA response may be associated with the precise location of the acupuncture point. If further studies confirm such findings, then EDA may become a valuable physiological marker for the acupuncture phenomenon.

Increased oscillatory theta activation evoked by violent digital game events

The authors examined electroencephalographic (EEG) oscillatory responses to two violent events, the player character wounding and killing an opponent character with a gun, in the digital game James Bond 007: NightFire. EEG was recorded from 25 (16 male) right-handed healthy young adults. EEG data were segmented into one 1-s baseline epoch before each event and two 1-s epochs after event onset. Power estimates (microV(2)) were derived with the fast Fourier transform (FFT) for each artefact free event. Both of the studied events evoked increased occipital theta (4-6Hz) responses as compared to the pre-event baseline. The wounding event evoked also increased occipital high theta (6-8Hz) response and the killing event evoked low alpha (8-10Hz) asymmetry over the central electrodes, both relative to the pre-event baseline. The results are discussed in light of facial electromyographic and electrodermal activity responses evoked by these same events, and it is suggested that the reported EEG responses may be attributable to affective processes related to these violent game events.

Effect of Movements on the Electrodermal Response after a Startle Event

In this work the effect of quasi-stationary movements on the electrodermal activity (EDA) after a startle event has been investigated and evaluated. In previous EDA research there is a discrepancy between the use of controlled environment studies and daily life surveys. This paper aims to address this by expanding the knowledge about EDA in real life applications. A minimally obtrusive body-worn measurement device was designed and produced that simultaneously records EDA and finger movements. During this study, five subjects walked at different speeds and listened to startling sound events. The EDA response to these startle events was analyzed for different walking speeds using crosscorrelograms and cumulative frequency plots. The measured response to the startle event is consistent with the signal characteristics described in the literature. The results show that the faster a person is walking the more the signal property of the phasic part of the EDA is approaching a uniform distribution. However, even at a walking speed of 6 km/h the effect of the startle event is statistically still visible in the EDA (p < 0.05). The presented work offers a good understanding of the EDA while walking at different speeds. Although the artefacts evoked by walking cannot be determined directly, information on the movement can be useful. Depending on the walking speed a measurement about the reliability of peak detection could be introduced.

Dissociated autonomic regulation during stress and physical complaints

In order to evaluate the relevance of individual differences in the regulation of autonomic subsystems to psychosomatic processes, reactivity of the autonomic nervous system to an emotional stressor was related to the occurrence of physical complaints. In contrast to most other studies, the measures were related to the degree of actually experienced stress. In a large sample (n=111), electrodermal activity (EDA) and heart rate variability (HRV) were obtained at rest and during emotional stress. Physical complaints were assessed by a standardized symptom checklist providing subscales for different physiological systems. Subjects who were actually stressed by the stress induction procedure but showed only weak reactivity of EDA, and subjects who were only slightly stressed but showed a marked EDA response reported a high amount of gastrointestinal complaints. A greater decrease of high-frequency HRV from the rest to the stress condition was associated with reports of relatively more cardiovascular complaints. Findings indicate that the link between regulation of EDA and gastrointestinal functions has to be localized in higher brain structures and support the hypothesis that minor autonomic dysregulation may represent one pathway linking negative affect and the development of physical disorders.

Altered electrodermal response to facial expression after closed head injury

Summary : The objective was to determine whether diffuse damage to orbital and ventromedial regions of the prefrontal cortex usually associated with moderate-to-severe closed head injury (CHI) would affect the ability to perceive and respond to socially relevant information. Methods : Participants with CHI and age-matched non-injured controls were presented with faces that varied with respect to emotional expression while electrodermal activity (EDA) was monitored. Cognitive and general adaptive functioning was also assessed. Results : CHI was associated with a failure to increase EDA in response to negative facial expressions and with reduced ability to identify negative expressions, especially fear. The groups differed on other signs of orbital/medial prefrontal damage such as anosmia and in general social adaptability and awareness-of-deficit as measured by the Brock Adaptive Functioning Questionnaire. Conclusions : CHI affected the ability to identify and respond to negative facial expression. Addressing these deficits may enhance rehabilitative efforts within the social domain.

Emotional Cognition without Awareness after Unilateral Temporal Lobectomy in Humans

To investigate the function of the amygdala in human emotional cognition, we investigated the electrodermal activity (EDA) in response to masked (unseen) visual stimuli. Six epileptic subjects were investigated after unilateral temporal lobectomy. Emotionally valenced photographic slides (10 negative, 10 neutral) from the International Affective Picture System were presented to their unilateral visual fields under either subliminal or supraliminal conditions. An interaction between hemispheres and emotional valences was found only under the subliminal conditions; greater EDA responses to negative stimuli compared with neutral ones were observed when stimuli were presented to the intact hemispheres. The findings suggest that nonconscious emotional processing is reflected in EDA in a different manner from conscious emotional processing. Medial temporal structures, including the amygdala, thus appear to play a critical role in the neural substrates for this automatic processing.

Electrodermal activity in schizophrenia: a quantitative study using a short interstimulus paradigm

Background: Electrodermal activity in response to short interstimulus interval (ISI) stimulation allows aspects of information processing to be examined, but such paradigms cause skin conductance responses (SCRs) to overlap. A signal decomposition method was developed and employed to score the overlapped SCRs. This is the first application of the method to the study of schizophrenia. Methods: Electrodermal activity of 30 medicated patients with schizophrenia and 50 normal controls was obtained using a conventional auditory oddball paradigm with an ISI of 1.3 sec. Tonic skin conductance level (SCL), phasic SCRs, SCR temporal dynamics, and a range of SCR variables in response to target tones were examined. Results: The schizophrenic group showed reduced response rate, proportion of responders, SCR amplitude, rise time, peak latency, and steady-state response amplitude over the trial compared with controls. There were no between-group differences in SCL or SCR onset time. Conclusions: The combined use of a conventional short ISI paradigm and the new SCR scoring method demonstrated new facets of electrodermal hyporeactivity in medicated patients with schizophrenia. The hyporeactivity could not be attributed to changes in tonic arousal or dysfunctions in peripheral sympathetic nerve conductance.

The effects of length of interstimulus interval on psychophysiological responses and on self-reported arousal

The effects of temporal distribution of noise stimuli were measured by means of psychophysiological responses and a self-reported arousal inventory. Three groups received either 120, 30 or 10 stimuli within a 90 min session (average interstimulus interval either 45 sec, 3 min or 10 min). Results indicated a linear relationship between interstimulus interval (ISI) length and electrodermal activity (EDA) and peripheral vascular responding. The group with the shortest ISI habituated fastest. Progressively less habituation occurred as the ISI became longer. The group with the longest ISI had a significantly larger cardiac deceleration than either of the other groups. There was no relationship between the three ISI groups with regard to subjectively experienced arousal. However, persons scoring high on the Stress factor on the inventory showed larger EDA responses and a larger cardiac acceleration than persons scoring low, regardless of original group affiliation. Results are discussed in terms of habituation, orienting, and defense, and are viewed as confounding some of the assumptions widely held by researchers interested in human responses to noise.

Hemispheric asymmetry and emotion: Effects of nonverbal affective stimuli

The purpose of the present study was to investigate the cerebral processing of affect by measuring the electroencephalographic activity of the frontal lobes and electrodermal activity in response to a series of nonverbal affective stimuli. Cognitive and sensorimotor processes were minimized by employing a design that did not require subjects to perform any task other than attending to the stimuli. Summated frontal alpha activity was determined during nonemotional, positive, and negative stimuli. Changes in bilateral skin conductance were also measured during the presentation of the stimuli. Results demonstrated that there was bilateral activation of the frontal lobes in response to the positive affective stimuli. The level of activation of the frontal lobes was the same in response to both negative and nonemotional stimuli. There was no evidence of hemispheric asymmetry or gender-related differences in patterns of activation. Furthermore, there was no evidence of lateralization in the skin conductance response magnitude.

Electrodermal characteristics in psychosomatic patient groups

Specific autonomic reaction patterns in different psychosomatic patient groups have been by several authors. In our study 50 male hypertensive patients and 47 male duodenal ulcer patients both in the early mild reversible stage of disease were compared with 65 male control persons to determine distinguishing features of electrodermal activity in response to a sequence of verbal, acoustic and colour stimuli. The two patient groups show opposite characteristics in respect to the initial skin resistance level, response amplitude and non-specific responses. Slower recovery can be seen only in an emotionally disturbing situation in the duodenal ulcer group. On the contrary, in orienting situations the control persons tend to show slower electrodermal recovery. According to the results of factor analysis, the components of electrodermal activity belong to 3 different factors, underlining the relative independence of these parameters. The first factor contains the electrodermal amplitude values. The temporal characteristics of electrodermal responses belong to two different factors, the first being in connection with the orienting situation and the second with the emotionally disturbing situation. The longer recovery in orienting situations is associated positively with facilitating achievement anxiety and negatively with debilitating achievement anxiety. The anxiety and neurosis scores belong to the third factor in connection with the prolonged electrodermal responses in emotionally disturbing situations. Anxiety and depression scores are higher in both patient groups, in accordance with the results of earlier studies. The parameters of electrodermal responses were analyzed as a function of psychological characteristics.