Gastric myoelectrical activity as an index of emotional arousal.

Autonomic nervous system parameters such as electrodermal activity, heart rate, and facial EMG have been utilized extensively as measures of emotional arousal. One measure that has rarely been employed in this setting is gastric myoelectrical activity, despite the fact that "gut feelings" have an obvious and even profound role in everyday emotional life. It has been shown that the gastrointestinal system changes wall tonus and contraction rate during stressful tasks. However, the effects of emotionally salient stimuli on gastrointestinal motility have scarcely been studied. In the current study, emotional film clips designed to elicit happiness, disgust, fear, sadness, or no emotion (neutral) were presented to 16 normal participants. Electrogastrogram (EGG), skin conductance, and heart rate were measured while the participants viewed the film clips, and participants rated subjective arousal intensity and pleasantness of the film clips. We found that emotional film clips reliably induced the intended subjective feeling states. Also, EGG peak amplitudes in fear, disgust, sadness and happiness were higher than in the no emotion condition. There was a strong positive correlation (r=0.64) between EGG peak amplitude and subjective ratings of arousal. This is the first evidence that gastric myoelectrical activity is strongly correlated with arousal ratings to emotionally salient stimuli, and it suggests that EGG may add useful information about how the body contributes to the phenomenology of emotion and feeling.     

Insomnia does not affect heart rate changes when young adults watch humorous films: An exploratory study

Emotional reactivity in insomnia is affected both subjectively and on a physiological level for negative emotional material, but little is known about reactions to positive stimuli. We here investigated whether in younger adult insomnia patients, presentation of short humorous films would lead to heart rate decreases during and after film viewing, as compared to heart rate changes when falling asleep. Investigating 20 participants with DSM‐5‐diagnosed insomnia and 18 participants without insomnia, we found that heart rate decreased when falling asleep, increased when watching humorous films and returned to normal values afterwards for all participants. Film‐related heart rate increases were strongly related to humour ratings of the films. No differences were found between those with and without insomnia on subjective ratings of the films, film‐related heart rate changes or when falling asleep. We conclude that the experience of positive daily life stimuli in younger adults is not affected by insomnia in our study, despite insomnia having a known more profound effect on negative stimuli. Future studies exploring insomnia‐related autonomous nervous system responses combining different neurophysiological modalities should confirm our findings.     

Intact physiological response to arousal with impaired emotional recognition in alexithymia

BACKGROUND: The purpose of the present study was to clarify the relationship between the recognition of emotion and physiological response to emotion (i.e. arousal) in alexithymia. METHODS: This study investigated differences in physiological arousal state, as measured by continuous heart rate, electrodermal activity (EDA) and self-reported emotional intensity before and after exposure to an emotionally arousing or neutral videotape among 41 high- or low-alexithymic young adult participants. RESULTS: Across subjects, emotionally negative stimuli produced increased physiological arousal. However, high-alexithymic participants exposed to the arousing videotape did not report increased subjective emotional intensity, as did low-alexithymic participants. In addition, the baseline EDA of high-alexithymic participants was significantly higher than that of the low-alexithymic participants. CONCLUSIONS: Results support the prediction that alexithymia leads to a decoupling between subjective and physiological arousal when exposed to emotionally negative stimuli. This decoupling may increase alexithymic individuals' risks for stress-related illness.     

Autonomic, neuroendocrine, and subjective responses to emotion-inducing film stimuli.

The aim of the present study was to investigate differential emotional response patterns to film stimuli by multimodal assessment of subjective, autonomic and endocrine variables. Scenes of two films, chosen to induce different affective states, were presented to 20 male subjects. Changes in mood and perceived bodily sensations, autonomic activity (heart rate and skin conductance) and one endocrine parameter (salivary cortisol) were measured. Analyses revealed that the films elicited differential mood patterns. The cartoon film, which induced a pleasant, amused state, was accompanied by very few changes in bodily sensations, a temporary decrease in heart rate, and a rapid decrease in electrodermal activity. The suspense film, which elicited a marked reduction in joyfulness and relaxation together with an enhancement in irritation, differed from that pattern primarily by marked changes in several bodily sensations, an increase in electrodermal activity, and a temporary decrease in heart rate. There were no film-dependent cortisol changes. The results together with evidence from other emotion induction experiments support the usefulness of film segments in eliciting mild to moderate affective states and their concomitances. They particularly point to the relevance of bodily sensations as an emotional response component.     

Physiological reactivity as a predictor of performance in a vigilance task

The experiment was designed to determine the value of measures of physiological activity as predictors of performance in a vigilance task. Subjects, for whom resting (EEG, heart rate, and skin conductance) and response (electrodermal) measures were available, were given an auditory vigilance task. Overall vigilance performance was significantly correlated with one measure of electrodermal habituation, latency of response to the first of a series of stimuli, and total number of responses to stimuli. None of the measures of resting physiological activity were significantly related to vigilance performance. The results are discussed in terms of Mackworth's (1969) theory of vigilance.     

The psychophysiology of mixed emotional states

How to conceptualize mixed emotional states is a central issue in the field of affective science. Nondifferentiation, additive, and emergence accounts of mixed emotions make divergent predictions regarding physiological responses in mixed emotions. To test these predictions, 43 women watched film clips that elicited amusement, disgust, or mixed emotions while feeling self‐report, facial electromyography, cardiovascular, electrodermal, and respiratory measures were assessed. Simultaneous self‐reports of amusement and disgust confirmed elicitation of a mixed emotional state. Physiologically, mixed emotions differed from pure amusement and pure disgust both in intensity and pattern. This suggests a distinct physiological response of the mixed emotional state, as predicted by the emergence account of mixed emotions. Implications for emotion theory and research are discussed.     

Cardiac responses associated with affective processing of unpleasant film stimuli.

The autonomic basis of cardiac reactions to unpleasant film stimuli was investigated. Film clips depicting major surgery, threats of violence, and neutral material were presented to 46 subjects. Self-report measures of emotion were obtained, as well as heart rate, respiration rate, respiratory sinus arrhythmia, T-wave amplitude and skin conductance level. Resting vagal tone was estimated in a paced breathing task prior to film viewing. Spontaneous blink rate was also taken as a measure of visual engagement during film viewing. Coherent increases in sympathetic activation accompanied the film containing violent threats, whereas the surgery film yielded greater electrodermal activation, as well as heart rate deceleration and T-wave increase. These data support the hypothesis of differential autonomic response patterns to specifically unpleasant material. As compared with threat and neutral films, greater blink rate inhibition was observed during the surgery film. Individual differences in parasympathetic cardiac control measured at rest were able to discriminate cardiac response patterns during film viewing.     

The psychophysiology of mixed emotional states: Internal and external replicability analysis of a direct replication study

The replicability of emotion‐related physiological changes constitutes a fundamental issue in affective science. We undertook a direct replication of the physiological differentiation of amusement, disgust, and a mixed emotional state as previously reported (Kreibig, Samson, & Gross, 2013). In the current study, 48 women watched 54 amusing, disgusting, and mixed emotional film clips while cardiovascular, electrodermal, and respiratory measures were obtained. Primary analyses indicated physiological differentiation of the mixed emotional state from amusement and disgust. We evaluated (a) the probability that future replications of the current study would yield similar results using bootstrapped confidence intervals of effect sizes, and (b) the stability of results of physiological reactivity between actual replications using correlation and regression analyses. Findings suggest replicable differentiation of amusement, disgust, and a mixed emotional state.     

Cardiovascular, electrodermal, and respiratory response patterns to fear- and sadness-inducing films

Responses to fear- and sadness-inducing films were assessed using a broad range of cardiovascular (heart rate, T-wave amplitude, low- and high-frequency heart rate variability, stroke volume, preejection period, left-ventricular ejection time, Heather index, blood pressure, pulse amplitude and transit time, and finger temperature), electrodermal (level, response rate, and response amplitude), and respiratory (rate, tidal volume and its variability, inspiratory flow rate, duty cycle, and end-tidal pCO(2)) measures. Subjective emotional experience and facial behavior (Corrugator Supercilii and Zygomaticus Major EMG) served as control measures. Results indicated robust differential physiological response patterns for fear, sadness, and neutral (mean classification accuracy 85%). Findings are discussed in terms of the fight-flight and conservation-withdrawal responses and possible limitations of a valence-arousal categorization of emotion in affective space.     

Individual Differences in Fear and Autonomic Reactions to Affective Stimulation

Klorman et al. (1975) found that mutilation-fearful persons reacted with heart rate speeding to mutilation slides and to neutral stimuli. The within-subject design of that study suggested that these paradoxical reactions to neutral slides may have been due to subjects' anticipation of phobic materials. In the present work, 84 female subjects, categorized by a standardized questionnaire as high or low in fear of mutilation, viewed one of three types of slides: 1) mutilated bodies; 2) persons and objects in incongruous or humorous poses; or 3) standard photographs of persons, objects, and landscapes. Mutilation materials evoked cardiac acceleration and high subjective tension in fearful subjects vs bradycardia and moderate tension in low-fear subjects. Neutral and incongruous slides prompted similar reactions from both fear groups: heart rate deceleration and low tension. Low-fear subjects shown mutilation slides tended to exceed the groups receiving nonaversive stimulation in magnitude of cardiac deceleration. Extensive analyses of respiratory activity showed that these differential heart rate reactions were not attributable to breathing. Mutilation stimuli evoked greater skin conductance responses than nonaversive slides, but there were no electrodermal differences as a function of fear relevance. The lawful relationship uncovered in the present research between cardiac reactions and individual differences in fear supports our suggestion that anticipation may have played a role in our earlier work.     

Paranoid-nonparanoid differences--psychophysiological parallels.

It was predicted that the psychological differences between paranoids and nonparanoids would be parallelled by differences in psychophysiological responses to stimuli varying along both informational and motivational dimensions. Skin conductance and heart rate responses to stimuli in a guessing task were measured in a group of paranoid patients and compared with those from non-paranoid and non-patient controls. A group of nonschizophrenic patients on phenothiazine medication served as drug-matched controls. Skin conductance level, response frequency and amplitude data are reported; heart rate response changes were examined by means of times series analysis and reported as first and second deceleration and first and second acceleration components. It was predicted that paranoid patients would show a greater increase in skin conductance measures with cognitive demand, and an increase in acceleratory components of the heart rate to increases in motivational variables. The normal pattern of greater electrodermal responding to the negative stimuli than the positive, and greater heart rate acceleration to the positive stimuli but not the negative (Fowles, 1980) was predicted to be reversed in schizophrenic patients, and possibly more marked in paranoids. Cognitive manipulations showed the predicted increase in electrodermal and heart rate responding in normal controls. The paranoid subjects showed a similar increase as a function of task demands, but there was no significant difference between the other groups. Motivational manipulations produced increased skin conductance responding and increases in heart rate acceleration components in normal controls, this was not parallelled in the patient groups. All subject groups failed to show greater electrodermal activity to negative than to positive stimuli. Normal controls showed significant heart rate acceleration to positive as compared to negative stimuli, this pattern was reversed in paranoid patients.     

Electrodermal lability as an indicator for subjective sleepiness during total sleep deprivation

The present study addresses the suitability of electrodermal lability as an indicator of individual vulnerability to the effects of total sleep deprivation. During two complete circadian cycles, the effects of 48h of total sleep deprivation on physiological measures (electrodermal activity and body temperature), subjective sleepiness (measured by visual analogue scale and tiredness symptom scale) and task performance (reaction time and errors in a go/no go task) were investigated. Analyses of variance with repeated measures revealed substantial decreases of the number of skin conductance responses, body temperature, and increases for subjective sleepiness, reaction time and error rates. For all changes, strong circadian oscillations could be observed as well. The electrodermal more labile subgroup reported higher subjective sleepiness compared with electrodermal more stable participants, but showed no differences in the time courses of body temperature and task performance. Therefore, electrodermal lability seems to be a specific indicator for the changes in subjective sleepiness due to total sleep deprivation and circadian oscillations, but not a suitable indicator for vulnerability to the effects of sleep deprivation per se.     

Psychophysiological responses to pain: Further validation of the nociceptive flexion reflex (NFR) as a measure of nociception using multilevel modeling

Physiological reactions to noxious stimuli are often used to make inferences about pain, but few studies have thoroughly examined the intra- and interindividual relationships between them. In the present study ( N =104), multilevel analyses was used to assess relations between physiological (nociceptive flexion reflex magnitude [NFR], blink reflex magnitude, skin conductance response [SCR], heart rate [HR]) and subjective reactions to electrocutaneous stimuli. All physiological reactions were significant predictors of ratings when entered alone, explaining 1% (SCR) to 29% (NFR) of the variance; but only NFR, blink, and HR were significant in a multivariate predictor model. Significant interindividual variability in slopes was found for blink and HR, but not NFR. A final trimmed model that included NFR, blink, and the blink random slope explained 35% of the variance in ratings.     

The Inhibition of Cardiovascular Responses to Mental Stress Following Aerobic Exercise

The effects of exercise on subsequent psychophysiological responses to mental stress were assessed in a study of 30 normotensive male volunteers. Participants were randomly allocated to three experimental conditions--20-min exercise at 100 Watts (high exercise), 20-min exercise at 25 Watts (low exercise), or 20-min no exercise (control). After a recovery period of 20 min, all subjects performed a mental arithmetic task for four 5-min trials. Blood pressure and heart rate were monitored continuously using a Finapres, and respiration and electrodermal activity were also recorded. Baroreceptor reflex control of heart rate was assessed using power spectrum analysis. Exercise produced consistent increases in systolic blood pressure, heart rate, and subjective tension, together with reductions in systemic resistance and baroreflex sensitivity. The systolic and diastolic blood pressure and heart rate reactions to mental arithmetic were significantly blunted in the high exercise compared with control conditions, with the low exercise group showing an intermediate pattern. Subjective responses to mental stress were unaffected by prior exercise. The pattern of hemodynamic response was not a result of changes in baroreflex sensitivity. The mechanisms underlying this result are discussed in relation to the discrepancies between subjective and physiological responses to mental stress, and the implications for the use of exercise in stress management.     

The impact of cardiac perception on emotion experience and cognitive performance under mental stress

Mental stress evokes several physiological responses such as the acceleration of heart rate, increase of electrodermal activity and the release of adrenaline. Moreover, physiological stress responses interact with emotional and behavioral stress responses. In the present study we provide evidence that viscero-sensory feedback from the heart (cardiac perception) is an important factor modulating emotional and cognitive stress responses. In our study, we compared participants with high versus low cardiac perception using a computerized mental stress task, in which they had to respond to rapidly presented visual and acoustic stimuli. Additionally, we assessed physiological responses (heart rate, skin conductance). Participants high in cardiac perception reported more negative emotions and showed worse task performance under the stressor than participants low in cardiac perception. These results were not moderated by physiological responses. We conclude that cardiac perception modulates stress responses by intensifying negative emotions and by impairing cognitive performance.     

Controlling the emotional heart: Heart rate biofeedback improves cardiac control during emotional reactions

When regulating negative emotional reactions, one goal is to reduce physiological reactions. However, not all regulation strategies succeed in doing that. We tested whether heart rate biofeedback helped participants reduce physiological reactions in response to negative and neutral pictures. When viewing neutral pictures, participants could regulate their heart rate whether the heart rate feedback was real or not. In contrast, when viewing negative pictures, participants could regulate heart rate only when feedback was real. Ratings of task success paralleled heart rate. Participants' general level of anxiety, emotion awareness, or cognitive emotion regulation strategies did not influence the results. Our findings show that accurate online heart rate biofeedback provides an efficient way to down-regulate autonomic physiological reactions when encountering negative stimuli.     

Food deprivation and emotional reactions to food cues: implications for eating disorders.

Two studies examined emotional responding to food cues. In experiment 1, normal college students were assigned to 0-, 6- or 24-h of food deprivation prior to presentations of standard emotional and food-related pictures. Food deprivation had no impact on responses elicited by standard emotional pictures. However, subjective and psychophysiological reactions to food pictures were affected significantly by deprivation. Importantly, food-deprived subjects viewing food pictures showed an enhanced startle reflex and increased heart rate. Experiment 2 replicated the food deprivation effects from experiment 1, and examined participants reporting either a habitual pattern of restrained (anorexia-like) or binge (bulimia-like) eating. Food-deprived and binge eater groups showed startle potentiation to food cues, and rated these stimuli as more pleasant, relative to restrained eaters and control subjects. The results are interpreted from the perspective that startle modulation reflects activation of defensive or appetitive motivation. Implications of the data for understanding eating disorders are considered.     

Confrontation with blood and disgust stimuli precipitates respiratory dysregulation in blood-injection-injury phobia

Blood-injection-injury (BII) phobia patients sometimes faint during exposure to relevant stimuli. However, mechanisms and timing of physiological adjustments in BII phobia remain poorly understood. In a larger sample of 60 patients and 20 controls, we sought to replicate findings of a prior study demonstrating the role of hyperventilation in the phobic response. We also investigated the timing of respiratory adjustment across an extended exposure recovery period. In addition, because intense disgust is commonly reported by patients, responses to surgery films were compared to a pure disgust film. End-tidal PCO₂ dropped significantly while volume and flow increased during the surgery film in patients compared to controls and to other emotional films except disgust. Patients recovered quickly following the disgust film but not the surgery film. PCO₂, volume, and flow parameters showed robust associations with anxiety, disgust, and physical symptoms. Findings suggest that respiratory adjustments during and after phobic exposure may provide a critical missing link in the understanding of the psychophysiology of this singular disorder, including why fainting often occurs after the stimulus is removed.