Electrodermal Measures Research Articles

The Effects of Noise and Simulated Conductive Hearing Loss on Physiological Response Measures During Interactive Conversations.

The purpose of this work was to study the effects of background noise and hearing attenuation associated with earplugs on three physiological measures, assumed to be markers of effort investment and arousal, during interactive communication. Twelve pairs of older people (average age of 63.2 years) with age-adjusted normal hearing took part in a face-to-face communication to solve a Diapix task. Communication was held in different levels of babble noise (0, 60, and 70 dBA) and with two levels of hearing attenuation (0 and 25 dB) in quiet. The physiological measures obtained included pupil size, heart rate variability, and skin conductance. In addition, subjective ratings of perceived communication success, frustration, and effort were obtained. Ratings of perceived success, frustration, and effort confirmed that communication was more difficult in noise and with approximately 25-dB hearing attenuation and suggested that the implemented levels of noise and hearing attenuation resulted in comparable communication difficulties. Background noise at 70 dBA and hearing attenuation both led to an initial increase in pupil size (associated with effort), but only the effect of the background noise was sustained throughout the conversation. The 25-dB hearing attenuation led to a significant decrease of the high-frequency power of heart rate variability and a significant increase of skin conductance level, measured as the average z value of the electrodermal activity amplitude. This study demonstrated that several physiological measures appear to be viable indicators of changing communication conditions, with pupillometry and cardiovascular as well as electrodermal measures potentially being markers of communication difficulty.

Listener characteristics differentially affect self-reported and physiological measures of effort associated with two challenging listening conditions

Listeners vary in their ability to understand speech in adverse conditions. Differences in both cognitive and linguistic capacities play a role, but increasing evidence suggests that such factors may contribute differentially depending on the listening challenge. Here, we used multilevel modeling to evaluate contributions of individual differences in age, hearing thresholds, vocabulary, selective attention, working memory capacity, personality traits, and noise sensitivity to variability in measures of comprehension and listening effort in two listening conditions. A total of 35 participants completed a battery of cognitive and linguistic tests as well as a spoken story comprehension task using (1) native-accented English speech masked by speech-shaped noise and (2) nonnative accented English speech without masking. Masker levels were adjusted individually to ensure each participant would show (close to) equivalent word recognition performance across the two conditions. Dependent measures included comprehension tests results, self-rated effort, and electrodermal, cardiovascular, and facial electromyographic measures associated with listening effort. Results showed varied patterns of responsivity across different dependent measures as well as across listening conditions. In particular, results suggested that working memory capacity may play a greater role in the comprehension of nonnative accented speech than noise-masked speech, while hearing acuity and personality may have a stronger influence on physiological responses affected by demands of understanding speech in noise. Furthermore, electrodermal measures may be more strongly affected by affective response to noise-related interference while cardiovascular responses may be more strongly affected by demands on working memory and lexical access.

Selective preservation of changes to standing balance control despite\xa0psychological and autonomic habituation\xa0to a postural threat

Humans exhibit changes in postural control when confronted with threats to stability. This study used a prolonged threat exposure protocol to manipulate emotional state within a threatening context to determine if any threat-induced standing behaviours are employed independent of emotional state. Retention of balance adaptations was also explored. Thirty-seven adults completed a series of 90-s standing trials at two surface heights (LOW: 0.8 m above ground, away from edge; HIGH: 3.2 m above ground, at edge) on two visits 2–4 weeks apart. Psychological and autonomic state was assessed using self-report and electrodermal measures. Balance control was assessed using centre of pressure (COP) and lower limb electromyographic recordings. Upon initial threat exposure, individuals leaned backward, reduced low-frequency centre of pressure (COP) power, and increased high-frequency COP power and plantar/dorsiflexor coactivation. Following repeated exposure, the psychological and autonomic response to threat was substantially reduced, yet only high-frequency COP power and plantar/dorsiflexor coactivation habituated. Upon re-exposure after 2–4 weeks, there was partial recovery of the emotional response to threat and few standing balance adaptations were retained. This study suggests that some threat-induced standing behaviours are coupled with the psychological and autonomic state changes induced by threat, while others may reflect context-appropriate adaptations resistant to habituation.

Effectiveness of Noise-Attenuating Headphones on Physiological Responses for Children With Autism Spectrum Disorders.

Objective: The purpose of this study was to evaluate the proof of concept of an intervention to decrease sympathetic activation as measured by skin conductivity (electrodermal activity, EDA) in children with an autism spectrum disorder (ASD) and auditory hypersensitivity (hyperacusis). In addition, researchers examined if the intervention provided protection against the negative effects of decibel level of environmental noises on electrodermal measures between interventions. The feasibility of implementation and outcome measures within natural environments were evaluated.Method: A single-subject multi-treatment design was used with six children, aged 8–16 years, with a form of Autism (i.e., Autism, PDD-NOS). Participants used in-ear (IE) and over-ear (OE) headphones for two randomly sequenced treatment phases. Each child completed four phases: (1) a week of baseline data collection; (2) a week of an intervention; (3) a week of no intervention; and (4) a week of the other intervention. Empatica E4 wristbands collected EDA data. Data was collected on 16–20 occasions per participant, with five measurements per phase.Results: Separated tests for paired study phases suggested that regardless of intervention type, noise attenuating headphones led to a significance difference in both skin conductance levels (SCL) and frequency of non-specific conductance responses (NS-SCRs) between the baseline measurement and subsequent phases. Overall, SCL and NS-SCR frequency significantly decreased between baseline and the first intervention phase. A protective effect of the intervention was tested by collapsing intervention results into three phases. Slope correlation suggested constant SCL and NS-SCR frequency after initial use of the headphones regardless of the increase in environmental noises. A subsequent analysis of the quality of EDA data identified that later phases of data collection were associated with better data quality.Conclusion: Many children with ASD have hypersensitivities to sound resulting in high levels of sympathetic nervous system reactivity, which is associated with problematic behaviors and distress. The findings of this study suggest that the use of noise attenuating headphones for individuals with ASD and hyperacusis may reduce sympathetic activation. Additionally, results suggest that the use of wearable sensors to collect physiological data in natural environments is feasible with established protocols and training procedures.

Does Co-Occurring Anxiety Modulate ADHD-Related Cognitive and Neurophysiological Impairments?

Objective: This study investigates whether anxiety modulates cognitive-performance, electrophysiological and electrodermal processes that we previously found impaired in individuals with ADHD. Method: Self-reported anxiety symptoms, cognitive-electrophysiological measures of response inhibition, working memory, attention, conflict monitoring, error processing, and peripheral arousal during three cognitive tasks were obtained from 87 adolescents and young adults with ADHD and 169 controls. We tested the association of anxiety symptoms with each measure and whether controlling for anxiety symptoms attenuates the ADHD–control difference for each measure. Results: Individuals with ADHD showed significantly elevated anxiety symptoms compared with controls. Only commission errors on a Continuous Performance Test (measuring response inhibition) were significantly associated with anxiety symptoms and only among controls, with the ADHD–control difference in this measure remaining significant. Conclusion: Using a wide range of cognitive, electrophysiological, and electrodermal measures, our investigation suggests, overall, limited malleability of these impairments in individuals with ADHD irrespective of their levels of anxiety.

Adaptation of emotional state and standing balance parameters following repeated exposure to height-induced postural threat

Height-induced postural threat influences standing balance control. However, it is unknown if minimizing individuals’ emotional response to threat moderates this relationship. This study repeatedly exposed individuals to height-induced postural threat to determine if reducing the emotional response to threat influences standing balance control. Sixty-eight young adults completed a series of standing trials at LOW (0.8 m above ground, away from edge) and HIGH (3.2 m above ground, at edge) postural threat conditions. Emotional state was assessed using self-report and electrodermal measures. Standing balance was assessed through analysis of centre of pressure (COP) movement and lower leg electromyographic activity. Individuals’ emotional response to threat was attenuated following repeated threat exposure. However, threat-induced changes in standing balance were largely preserved. When initially threatened, individuals leaned backward and demonstrated smaller amplitude and higher frequency of COP adjustments; these balance outcomes did not change following repeated threat exposure. Only high frequency COP oscillations (>1.8 Hz) and ankle muscle co-contraction showed any adaptation; regression analyses showed that these behavioural adaptations were accounted for by a combination of emotional and cognitive state changes. This suggests that some threat-induced standing balance changes are more closely linked with the emotional response to threat than others, and are therefore amendable to intervention.

Increase in Electrodermal Activity on Acupuncture Points of Lymphatic, Lung, Nervous, Endocrine and Heart Meridians after Running Exercise, a Single Case Study

Background: Electrodermal measurement of acupuncture points has been correlated to physiologic and pathologic conditions with clinical and laboratory studies. Emerging evidence indicates that in addition to therapeutic effect, acupuncture points may also have diagnostic properties. However, physiologic basis of this phenomenon is still unknown. Objective: To determine how electrodermal activity of acupuncture points on hands and feet responds to exercise-induced sympathetic stress and how electrodermal measurement correlates to skin temperature. Materials and Methods: A 20-minute running exercise with a moderate intensity based on Borg Rating of Perceived Exertion Scale was carried out with one healthy male subject for 15 sessions. Electrodermal activity of acupuncture points was tested before and after exercise with a meridian testing system, Electroacupuncture According to Voll. Bio signs including heart rate, breathing rate, blood oxygen level and skin temperature for forehead, hands and feet were also measured. Result: Significant increase in electrodermal activity for five hand meridians, including Lymphatic, Lung, Nervous system, Endocrine systems and Heart, was observed after exercise. There was no significant change for the rest of hand meridians and foot meridians. Significant increase in foot skin temperature and decrease in hand and forehead temperature were also observed after exercise. The change in skin temperature for hand and foot was inversely related to that of electrodermal measures. Conclusion: Despite the limitations, the finding of the study is consistent with expected physiologic responses to the stress due to running exercise and it is feasible to conduct clinical studies with larger sample size to further study the change of electrodermal activity of acupuncture points after exercise. It also suggests that electrodermal testing of acupuncture points may be useful to detect stresses from corresponding organs and tissues. More clinical and mechanistic studies are warranted.

Developmental dynamics of autonomic function in childhood.

There is a paucity of developmental data examining the stability of autonomic function during childhood, and even less is known regarding the extent of coordination between autonomic branches. To address this, autonomic measures of sympathetic (cardiac pre-ejection period, PEP; electrodermal activity, and EDA) and parasympathetic (respiratory sinus arrhythmia and RSA) function were collected from 339 children annually from kindergarten to second grade. Physiology was quantified into 31 epochs 30s in length, across a series of baselines and emotion-inducing films. Rank-order stability was observed for all three indices, but was higher for cardiac than electrodermal measures. A series of multilevel models was used to identify the proportion of variance in psychophysiological function attributable to the individual (trait), visit (potential developmental change), or epoch (reactivity to task). Both PEP and RSA had sizeable components of individual-level variance, with PEP showing very small variance attributable to experimental task. In contrast, variance in EDA was largely attributable to task epoch. Variance decompositions of the parasympathetic-sympathetic coordination (e.g., RSA-EDA) suggest that the branches of the autonomic system are prototypically cooperative, but evidence did not indicate traitlike stability or linear developmental change. The extent of coordination was moderated by emotional context, indicating that autonomic coordination varies dynamically within individuals. These findings have implications for future work attempting to identify the contextual, experiential, and demographic factors that modulate developmental trajectories of autonomic function and coordination, and for examination of how developmental changes in autonomic psychophysiology are related to or predict behavioral trajectories across a range of psychological domains.

P24. Psychology of Monosynaptic T (tendon) and H (Hoffmann) Reflexes (MSR) – History, results and relevance

Soon after monosynaptic reflexes were discovered (Erb 1875, Westphal 1875) studies concerning supraspinal influences including psychophysiological effects were carried out. A survey of methods with some historical illustrations and results of experiments from nearly a century of research is given. Lombard (1887, AmJPsychol, vol. one) was the first to show tonic variations of the ‘knee jerk’ due to psychophysiological influences, whereas Bowditch and Warren (1890) showed phasic activation with sophisticated techniques, allowing short time registration within the range of 0 to about 2000 ms after different kinds of stimuli. Lee and Kleitmann (1923) and Tuttle (1924) investigated effects of sleep and sleep deprivation. Paillard (1955) introduced simultaneous registration of T and H reflexes of the triceps surae into psychophysiological research. T reflexes were more reactive than H reflexes, in general, but one proband could reduce T and even H reflexes in a kind of biofeedback when watching the oscilloscope. Bathien and his group (1969, 1971) found increased T and H reflexes under intense attention (rsp. increased H reflexes only with highest activation). Brunia (1970, 1971ff) described significant elevations only of T reflexes during a vigilance task, and variations under different other experimental conditions including drugs. Sczesni and Kröner (1985) registered changes of T reflexes (as well as GSR parameters) under task conditions an in relaxation in probands practicing Autogenic Training (AT) compared to naïve persons, but failed to prove differences between the groups. It was shown that eliciting MSR, which of course is slightly ‘invasive’, but monotonous, was not considerably disturbing. Considering patients’ states of activation in everyday clinical examination is relevant, but MSR studies were also useful in psychophysiological research. MSR are the first parameters used in psychophysiological studies (introduced even before electro dermal measures, SCL and GSR). Changes can represent tonic as well as phasic psychological influences on the spinal level. T-reflexes are more variable than H-reflexes, but the latter also react. The differences were explained by a higher reactiveness of γ than of α motoneurons to influences from the reticular formation. Psychophysiological MSR studies were no longer carried out in the recent years, presumably because of the vast technical equipment needed, rather than other limitations.

Attend or defend? Sex differences in behavioral, autonomic, and respiratory response patterns to emotion–eliciting films

Sex differences in emotional reactivity have been studied primarily for negative but less so for positive stimuli; likewise, sex differences in the psychophysiological response-patterning during such stimuli are poorly understood. Thus, the present study examined sex differences in response to negative/positive and high/low arousing films (classified as threat-, loss-, achievement-, and recreation-related, vs. neutral films), while measuring 18 muscular, autonomic, and respiratory parameters. Sex differences emerged for all films, but were most prominent for threat-related films: Despite equivalent valence and arousal ratings, women displayed more facial-muscular and respiratory responding than men and pronounced sympathetic activation (preejection period, other cardiovascular and electrodermal measures), while men showed coactivated sympathetic/parasympathetic responding (including increased respiratory sinus arrhythmia). This indicates a prototypical threat-related defense response in women, while men showed a pattern of sustained orienting, which can be understood as a shift toward less threat proximity in the defense cascade model. Clinical implications are discussed within a socio-evolutionary framework.

Embodied neurofeedback with an anthropomorphic robotic hand.

Neurofeedback-guided motor imagery training (NF-MIT) has been suggested as a promising therapy for stroke-induced motor impairment. Whereas much NF-MIT research has aimed at signal processing optimization, the type of sensory feedback given to the participant has received less attention. Often the feedback signal is highly abstract and not inherently coupled to the mental act performed. In this study, we asked whether an embodied feedback signal is more efficient for neurofeedback operation than a non-embodiable feedback signal. Inspired by the rubber hand illusion, demonstrating that an artificial hand can be incorporated into one’s own body scheme, we used an anthropomorphic robotic hand to visually guide the participants’ motor imagery act and to deliver neurofeedback. Using two experimental manipulations, we investigated how a participant’s neurofeedback performance and subjective experience were influenced by the embodiability of the robotic hand, and by the neurofeedback signal’s validity. As pertains to embodiment, we found a promoting effect of robotic-hand embodiment in subjective, behavioral, electrophysiological and electrodermal measures. Regarding neurofeedback signal validity, we found some differences between real and sham neurofeedback in terms of subjective and electrodermal measures, but not in terms of behavioral and electrophysiological measures. This study motivates the further development of embodied feedback signals for NF-MIT.

Comment: Where is the Theory? A Critical Comment on Multiple Arousal Theory

Multiple arousal theory suggests that there is more than one arousal system and that the activity of the multiple arousal systems can be observed using electrodermal measures at various body sites. The ideas expressed by multiple arousal theory are interesting but they do not constitute a theory. The absence of a specific definition of arousal and the lack of testable predictions prevent multiple arousal theory from constituting a useful theoretical framework for focussed empirical research.

Autonomic responses to lateralized cold pressor and facial cooling tasks.

Asymmetry in central nervous system (CNS) control of autonomic nervous system (ANS) activity, a widely debated topic, was investigated via lateralized presentation of two ANS challenges: cold pressor, which elicits primarily sympathetic activation, and facial cooling, a predominantly vagal task. Seventy-three university students (37 female) engaged in these tasks while cardiovascular and electrodermal measures were acquired. Compared to right-side cold pressor, left cold pressor elicited generally larger cardiac, blood pressure, and skin conductance responses, but did not evoke asymmetric changes in heart rate variability. Facial cooling elicited significant increases in vagally mediated heart rate variability, but they were also not lateralized. These findings are consistent with reports of right hemisphere dominance in sympathetic regulation, but indicate that CNS vagal control is relatively symmetric. These results are framed in terms of polyvagal theory and neurovisceral integration two influential models of CNS-ANS integration in the service of adaptive environmental engagement.

Can yoga practices benefit health by improving organism regulation? Evidence from electrodermal measures of acupuncture meridians.

Objectives:To document and explain Yoga's effects on acupuncture meridian energies. To understand mechanisms behind Yoga's efficacy by testing links between yoga and traditional Chinese medicine.Materials and Methods:The study compared two groups of yoga practitioners: Novice and experienced. Novices consisted of 33 volunteers from a Swami Vivekananda Yoga Anusandhana Samsthana (S-VYASA) yoga instructor training module and the experienced practitioners were 20 resident SVYASA students. The intervention was 3 weeks of a yoga training program, new for the novices, but the lifestyle of the experienced group, who were therefore assessed only once. Novices were assessed on day 2 and 23 of their program at SVYASA's Yoga Medicine Hospital, making their data a pre-post, self-as-control, prospective study. Main outcome measures were mean acumeridian energy levels assessed by AcuGraph3 measures of electrodermal resistance at acupoints; additionally, gender differences, standard deviations (SDs) of all measures, and comparison of post and experienced group data.Results:Averaged energy levels significantly improved in all 24 meridians (maximum P = 0.032, 4-P < 0.01, and 19-P < 0.001). Females improved more than males (P < 0.05), both ending at similar levels to experienced practitioners, whose SDs were lower than novices on 19/24 meridians (mean F = 3.715, P = 0.0022), and 4/5 average variables.Conclusions:AcuGraph3 electrodermal measures contain substantial information, P << 0.00001. Yoga-lifestyle practice can increase and balance acumeridian energies; long-term practice decreases group SD's. These three suggest reasons why yoga practice impacts health: One, increased prana levels are important; two and three, improved physiological regulation is the key. Further studies relating traditional Indian and Chinese medical systems are needed.

Psychophysiological detection of concealed information shared by groups: An empirical study of the searching CIT.

This study focused on the application of the Concealed Information Test (CIT) to situations in which the crime-related information is shared by a group of suspects but is not available to the investigators (a method known as the "searching CIT," or SCIT). Twenty-two groups, each comprising 4 to 7 participants (115 in total), planned 1 of 2 mock crimes (kidnapping or bank robbery). While planning the crime, each group decided on 5 crime-related critical items (e.g., the city in which the bank was located). Each critical item was chosen from a predefined set of 4 alternatives. At a second stage, the SCIT was administered individually and each participant was tested on the 2 crimes-the actual planned crime, in which the participant was "guilty," and the unplanned crime, in which the participant was "innocent." Two algorithms, adopted from Breska, Ben-Shakhar, and Gronau (2012), were applied to detect the critical items and to differentiate between "guilty" and "innocent" participants. Findings revealed that differentiation efficiency based on electrodermal and respiration measures was identical to that obtained with the standard CIT when applied to large groups, but lower, although significantly greater than chance, when applied to differentiate between small groups.

Inter-operator Variability of Electrodermal Measure at Jing Well Points using AcuGraph 3

Recent studies have found that many factors, both biological and operator induced, influence electrodermal measurements. Here, we report on operator variability for a series of measurements made by four operators at Jing-Well points on 132 individuals of both sexes (68 males and 64 females) by using the AcuGraph 3 ‘Digital Meridian Imaging Tool’: Operator 1 (16 males, 12 females), Operator 2 (18 males, 13 females), Operator 3 (15 males, 21 females), and Operator 4 (19 males, 18 females). The individuals studied were attending a yoga therapy program for type 2 diabetes mellitus and were assessed on the 1st day of treatment. Large inter-operator variations in overall acumeridian energy readings were observed. For individual meridians, the AcuGraph 3 measure differed by up to 42 points for minimum values and 67 points for maximum values. After normalization, the data showed similar patterns between different acumeridians. This suggested that variations were caused by operators applying different pressures when making measurements. Thus, inter-operator variability should be considered when interpreting electrodermal measurements made by several different operators. Unless inter-operator variability is taken into account, actual values may not have meaning; only then can readings for the same population taken by different operators be evaluated correctly.

Linking components of event-related potentials and autonomic measures of the orienting reflex

This study examined autonomic measures and event-related potentials (ERPs) associated with elicitation and habituation of the basic Orienting Reflex (OR). Subjects received 16 innocuous tones with intensity alternating between 60 and 80dB, at long inter-stimulus intervals. There was no stimulus-related task, so we could examine the effects of stimulus novelty and intensity in the absence of task demands. Cardiac, respiratory, peripheral vasoconstriction, and electrodermal measures were recorded, as well as continuous EEG. Single-trial ERPs were obtained, and components extracted by Principal Components Analysis were examined for potential response fractionation in the central indices of stimulus processing. The predicted fractionation of autonomic measures was obtained: cardiac deceleration showed no systematic change with intensity or trials, respiratory pause showed a substantial main effect of trials but no intensity effects, peripheral vasoconstriction showed intensity but no trials effects, and electrodermal responses showed substantial main effects of trials and intensity. A range of intensity and novelty effects were obtained in components identified as the N1, P3a, P3b, Novelty P3, and the classic Slow Wave. The different stimulus–response profiles of the ERP components are discussed in relation to the autonomic response profiles within the context of a sequential processing theory of OR elicitation.

Electrodermal activity reliably captures physiological differences between wins and losses during gambling on electronic machines

Differential patterns of physiological arousal to win and loss events during gambling is central to psychological conceptualizations of gambling behaviors but is poorly researched. We recorded heart rate (HR) and skin conductance responses (SCRs) to wins and losses while 23 healthy participants played for small incentives on a simulated electronic gambling task. Wins produced large SCRs whereas losses did not, and large wins produced larger SCRs than small wins. Electrodermal measures also correlated with reward responsiveness on a personality measure and with ratings of excitement during gambling. HR evidenced a slight deceleration before event outcomes, and the rebound HR was larger after wins than after losses. The study demonstrates that physiological changes to gambling events can be reliably captured, and that these changes are sensitive to differential outcomes. These findings establish a foundation for future research in field settings.

Separation anxiety disorder in children: disorder‐specific responses to experimental separation from the mother

Separation anxiety disorder (SAD) is one of the most common anxiety disorders in childhood and is predictive of adult anxiety disorders, especially panic disorder. However, the disorder has seldom been studied and the attempt to distinguish SAD from other anxiety disorders with regard to psychophysiology has not been made. We expected exaggerated anxiety as well as sympathetic and respiratory reactivity in SAD during separation from the mother. Participants were 49 children with a principal diagnosis of SAD, 21 clinical controls (CC) with a principal diagnosis of anxiety disorder other than SAD, and 39 healthy controls (HC) not meeting criteria for any current diagnosis. Analyses of covariance controlling for age were used to assess sympathetic and parasympathetic activation (preejection period and respiratory sinus arrhythmia) as well as cardiovascular (heart rate, mean arterial pressure, total peripheral resistance), respiratory (total breath time, minute ventilation, tidal volume, end-tidal CO(2) , respiratory variability), electrodermal, and self-report (anxiety, cognitions, symptoms) variables during baseline, 4-min separation from, and reunion with the mother. Children with a diagnosis of SAD were characterized by elevated self-reported anxiety responses to separation and increased sympathetic reactivity compared with CC and HC groups. The SAD group also displayed greater vagal withdrawal and higher reactivity in multiple cardiovascular, respiratory, and electrodermal measures compared with the HC group, while corresponding responses were less in the CC group and not significantly different from the other groups. Separation from the mother elicits greater autonomic, respiratory, and experiential responses in children with SAD. Our findings based on brief experimental separation demonstrate differential subjective and physiological manifestations of specific anxiety diagnoses, thus supporting the validity of the diagnostic category of SAD.

Biofeedback and Epilepsy

Biofeedback is a noninvasive behavioral treatment that enables a patient to gain volitional control over a physiological process. As a treatment for epilepsy, biofeedback interventions were explored from as early as the 1970s, concentrating on sensory motor rhythm (SMR) as a neurophysiologic parameter. Whereas SMR biofeedback aims to modulate frequency components of the electroencephalography (EEG), slow cortical potential (SCP) biofeedback (which was introduced in the 1990s) focuses on the regulation of the amplitude of cortical potential changes (DC shift). In its application to epilepsy, biofeedback using galvanic skin response (GSR), an electrodermal measure of sympathetic activity, is a relatively new cost-effective methodology. The present article first reviews biofeedback using SMR and SCP, for which efficacy and neural mechanisms are relatively well characterized. Then recent data regarding promising applications of GSR biofeedback will be introduced and discussed in detail.