Deficits in early emotional reactivity in alexithymia

Alexithymia is characterized by a difficulty in identifying and describing one's emotions. This study addressed the question of whether alexithymic tendencies are related to limited affective reactivity to briefly presented emotional stimuli. Skin conductance responses were assessed and backward masking was used to minimize elaborated processing of emotional pictures. Results indicated that alexithymic tendencies are associated with smaller electrodermal responses to briefly presented negative pictures. These effects were driven by difficulties in identifying and communicating emotions whereas externally orientated thinking was unrelated to affective reactivity. We conclude that there is an early processing deficit in response to negative stimuli in participants with high scores in alexithymia. Differences in the early emotional reactivity to arousing material could contribute to difficulties in emotional processes related to alexithymia.     

Automatic facial responses to briefly presented emotional stimuli in autism spectrum disorder

Emotion processing, including automatic facial mimicry, plays an important role in social reciprocity. Disruptions in these processes have implications for individuals with impaired social functioning, such as autism spectrum disorders (ASDs). Past research has demonstrated that ASDs are impaired in the recognition of briefly presented emotions and display atypical mimicry of emotions presented for protracted duration. Mimicry (electromyography; EMG) of briefly presented emotions was investigated in adults with ASDs. Concurrent measures of skin conductance and cardiac responses were used as markers of orientation and stimulus detection, respectively. A backward masking task was employed whereby the emotional face (happy, angry) was presented for 30 ms followed by a neutral face “mask”. An implicit comparison task required rapid gender identification. The ASD group failed to differentiate by valence in their EMG (zygomaticus, corrugator) and demonstrated atypical pre- and post-stimulus arousal. These findings may provide a potential mechanism for marked deficits in social reciprocity.     

Respiratory sinus arrhythmia as an index of emotional response in young adults

The relationship between respiratory sinus arrhythmia (RSA) and valence and arousal remains unclear. In the present study, the associations between emotion responses and tonic or task-related changes in RSA were assessed. Specifically, the sensitivities of changes in interbeat interval, RSA, and skin conductance to the valence and arousal values of emotional stimuli were examined. This study also explored the association between tonic RSA and subjective, expressive, and physiological emotional responses. Response measures were collected from 56 adults during baseline and film-viewing periods. Tonic RSA was not significantly related to any of the response measures. Increased skin conductance and decreased RSA were associated with arousal independent of valence. Interbeat interval was related to affective valence and not arousal. These findings suggest that RSA may be a useful adjunct to skin conductance measures in assessing emotional arousal.     

Orienting response elicitation by personally significant information under subliminal stimulus presentation: Demonstration using the Concealed Information Test

Considerable evidence suggests that subliminal information can trigger cognitive and neural processes. Here, we examined whether elicitation of orienting response by personally significant (PS) verbal information requires conscious awareness of the input. Subjects were exposed to the Concealed Information Test (CIT), in which autonomic responses for autobiographical items are typically larger than for control items. These items were presented subliminally using two different masking protocols: single or multiple presentation of the masked item. An objective test was used to verify unawareness to the stimuli. As predicted, PS items elicited significantly stronger skin conductance responses than the control items in both exposure conditions. The results extend previous findings showing that autonomic responses can be elicited following subliminal exposure to aversive information, and also may have implications on the applied usage of the CIT.     

Emotional electrodermal response in coma and other low-responsive patients

Emotional processing in coma remains an open question. Skin conductance responses to emotional and neutral auditory stimuli were recorded in 13 low-responsive patients (12 of whom were in coma). A differential response between emotional and neutral stimuli was found, which significantly correlated with the Glasgow Coma Scale and the Cook and Palma score. These correlations indicate that emotional processing can occur in coma patients with relatively high clinical scores of reactivity.     

Electrocortical and electrodermal responses covary as a function of emotional arousal: a single-trial analysis

Electrophysiological studies of human visual perception typically involve averaging across trials distributed over time during an experimental session. Using an oscillatory presentation, in which affective or neutral pictures were presented for 6 s, flickering on and off at a rate of 10 Hz, the present study examined single trials of steady-state visual evoked potentials. Moving window averaging and subsequent Fourier analysis at the stimulation frequency yielded spectral amplitude measures of electrocortical activity. Cronbach's alpha reached values >.79, across electrodes. Single-trial electrocortical activation was significantly related to the size of the skin conductance response recorded during affective picture viewing. These results suggest that individual trials of steady-state potentials may yield reliable indices of electrocortical activity in visual cortex and that amplitude modulation of these indices varies with emotional engagement.     

Backward masking and skin conductance responses after conditioning to nonfeared but fear-relevant stimuli in fearful subjects

The present study examined two issues. Are skin conductance responses conditioned to fear-relevant stimuli, as contrasted with responses conditioned to fear-irrelevant stimuli, elicited after merely an automatic, nonconscious analysis of the stimulus content? Do fearful subjects show better conditioning to nonfeared but fear-relevant stimuli (e.g., conditioning to spiders in snake-fearing subjects) than do nonfearful subjects? Subjects afraid of snakes, but not of spiders, or vice versa (n= 32) and nonfearful subjects (n= 32) were shown either fear-relevant stimuli (snakes or spiders and rats) or fear-irrelevant stimuli (flowers and mushrooms) in a differential conditioning paradigm, where one of the stimuli was followed by an electric shock. During a subsequent extinction phase, the conditioned stimuli were presented under backward masking conditions, preventing their conscious recognition. Consistent with our hypothesis, during the masked extinction of the conditioned stimuli, differential skin conductance responses to conditioning and control stimuli remained only for subjects conditioned to fear-relevant stimuli. Both fearful and nonfearful control subjects had significantly larger differential electrodermal responses to fear-relevant than to fear-irrelevant stimuli. However, contrary to our hypothesis, fearful subjects did not show enhanced conditionability to their nonfeared but fear-relevant stimuli as compared with nonfearful control subjects.     

The pupil as a measure of emotional arousal and autonomic activation

Pupil diameter was monitored during picture viewing to assess effects of hedonic valence and emotional arousal on pupillary responses. Autonomic activity (heart rate and skin conductance) was concurrently measured to determine whether pupillary changes are mediated by parasympathetic or sympathetic activation. Following an initial light reflex, pupillary changes were larger when viewing emotionally arousing pictures, regardless of whether these were pleasant or unpleasant. Pupillary changes during picture viewing covaried with skin conductance change, supporting the interpretation that sympathetic nervous system activity modulates these changes in the context of affective picture viewing. Taken together, the data provide strong support for the hypothesis that the pupil's response during affective picture viewing reflects emotional arousal associated with increased sympathetic activity.     

The effect of emotional and attentional processes on blink startle modulation and on electrodermal responses

Emotional accounts of startle modulation predict that startle is facilitated if elicited during aversive foreground stimuli. Attentional accounts hold that startle is enhanced if startle-eliciting stimulus and foreground stimulus are in the same modality. Visual and acoustic foreground stimuli and acoustic startle probes were employed in aversive differential conditioning and in a stimulus discrimination task. Differential conditioning was evident in electrodermal responses and blink latency shortening in both modalities, but effects on magnitude facilitation were found only for visual stimuli. In the discrimination task, skin conductance responses, blink latency shortening, and blink magnitude facilitation were larger during to-be-attended stimuli regardless of stimulus modality. The present results support the notion that attention and emotion can affect blink startle modulation during foreground stimuli.     

Effects of trial order and differential conditioning on acquisition of differential shock expectancy and skin conductance conditioning to masked stimuli

Research suggests that when people are fear conditioned to masked spiders and snakes (electric shocks are contingent on only spiders or snakes), they acquire a conditional skin conductance response and can predict the occurrence of shocks even though they are unable to identify the masked spiders and snakes. Because in prior studies trial order was not completely random, it is unclear if findings were due to the contingencies from differential conditioning or a restricted trial order or both. When participants were assigned to four groups to disentangle effects of trial order and differential conditioning to masked pictures in acquisition, effects were obtained only for trial order. These findings demonstrate that trial order can result in conditioning. However, because effects were observed even for participants who reported unawareness of the contingency from trial order, results are consistent with the notion of hunches or gut feelings.     

Right hemisphere representation of autonomic conditioning to facial emotional expressions

In this experiment, a lateralized right hemisphere effect was found for electrodermal associative learning to facial emotional expressions. Sixty-two subjects were presented simultaneously with a slide of a happy face in the right or left visual half field (VHF) and a slide of an angry face in the opposite VHF. Four groups were formed by the combination of the two VHF positions of angry/happy faces and the administration/omission of shock unconditioned stimuli. The results showed that simultaneous presentation of the angry face to the right hemisphere and the happy face to the left hemisphere, together with shock, resulted in a strong conditioned association with the angry face and a relatively weak association with the happy face. Furthermore, simultaneous presentation of the angry face to the left hemisphere and the happy face to the right hemisphere, together with shock, resulted in a relatively weak association with both stimuli. No significant differences were found for the no-shock control groups. The present results confirm previous findings of a right hemisphere advantage for representation of associative learning.     

Relationship between evoked skin-conductance response and evaporative-water-loss response following acoustic stimulation

The relationship between changes in skin conductance s.c. and skin evaporative water loss e.w.l. has been studied. s.c. and e.w.l. have been recorded simultaneously from adjacent palmar skin areas of volunteers who were exposed to acoustic stimulation. s.c. has been recorded using a constant-voltage method. e.w.l. was recorded by evaporimetry, a measurement method which has high sensitivity and a short response time compared with previously used methods. The results show good correlation between the responses, indicating that the same mechanism controls both variables. The response in e.w.l. is delayed compared with the s.c. response.     

Effects of picture content and intensity on affective physiological response

This study evaluated the effects of affective intensity and thematic content of foreground photographic stimuli on various physiological response systems. This was accomplished by assessing responses to pictures that varied systematically in these parameters. Along with overall effects of picture valence reported in previous work, we found effects of thematic content (i.e., specific nature of objects/events depicted) for all measures except heart rate. In addition, we found that the magnitude of startle blink, skin conductance, and corrugator muscle reactions increased with increasing affective intensity of pictures. Additionally, for these three measures, intensity effects also interacted with effects of picture content. These results indicate that stimulus parameters of intensity and thematic content exert separate-and in some cases interactive-modulatory effects on physiological reactions to emotional pictures.     

Startle potentiation during anticipation of a noxious stimulus: Active versus passive response sets

The startle reflex response increases during aversive stimulus processing. This study examined whether differing response sets affected startle potentiation during anticipation of an aversive event. Two groups received a noxious noise blast following a 6-s warning cue. Subjects in the active group could press a switch to stop the noise; yoked passive subjects received the same noises with no control. Subjects in a yoked control group heard a soft tone following cue offset. Acoustic startle probes were presented during some of the warning periods and during some of the intertrial intervals. The major finding was that the active and passive groups did not differ in startle potentiation. In comparison with controls, startle reactions for both groups were larger and faster during the warning cue than between trials. The results suggest that the startle reflex indexes defensive response mobilization independently of specific task demands.     

Oxytocin response in a trust game and habituation of arousal

Oxytocin may be implicated in various sophisticated human processes, including attachment, trust, social perception, memory, and fear regulation. In this study, we explored the relationship between plasma oxytocin level measured after a task requiring intimate trust (secret sharing) and habituation of autonomic arousal (skin conductance response) in sixty healthy volunteers. Results revealed that oxytocin was elevated in the trust-related condition relative to a neutral baseline. In a cognitive stress condition (mental arithmetic task), there was no significant oxytocin elevation relative to the neutral condition. After controlling for age, gender, education, state anxiety and depression, we found a significant positive relationship between trust-related oxytocin level and habituation of autonomic arousal. This relationship was absent in the case of neutral (trust-unrelated) oxytocin level. These results suggest that the habituation of autonomic arousal is closely related to oxytocin released during trust-related social interactions.     

Differential conditioning to facial emotional expressions: effects of hemispheric asymmetries and CS identification

Previous studies on aversive learning have suggested a right hemispheric advantage for eliciting autonomic reactions to a masked conditioned facial stimulus (CS) depicting anger. The present study investigated the effects of visual field (VF), stimulus awareness, and emotional valence of the CSs on indicators of conditioning (bilateral SCRs, HR) using a differential conditioning paradigm (N = 41). In Group 1, four different negatively valenced facial expressions (CS+) but not four positively valenced CS- were associated with an unconditioned stimulus (US, aversive vocalization, 97 dB, 3 s) during acquisition. Group 2 received a treatment reversal with positive CS+ associated with the US. In a repeated measures design, CSs were presented with or without awareness during extinction (two weeks interval, order counterbalanced). SOAs were adapted for each subject and condition prior to the experiment so that identification performance was approaching chance level. The results revealed that both negative and positive facial expressions could be aversively conditioned providing evidence for a generalization of learning in the valence dimension. During extinction, preattentive negative CS+ presented to the left VF showed a trend towards greater electrodermal and cardiac reactions. However, no such effect emerged under full awareness of the CSs. These results confirm and further specify the nature of hemispheric asymmetries in emotional associative learning.     

Boosting up gamma-band oscillations leaves target-stimulus in masking out of awareness: Explaining an apparent paradox

Boost up gamma-band neuronal oscillations have been interpreted as a correlate of pertinent stimulus awareness. The validity of this observation-based conclusion can be rigorously tested if the basic methodological rule of investigating neural correlates of consciousness (NCC) is followed: the varying contents of consciousness should be contrasted with invariant stimulation. We asked whether reliable gamma-band oscillations recorded from primary visual cortex appear as signatures of target awareness in metacontrast masking with invariant stimulation parameters. Surprisingly, clear target-stimuli awareness was associated with less expressed gamma power. However, because when target awareness was effectively masked more gamma power of the EEG response was found, and because this gamma-boost emerged at the post-target time when mask information was presented, we were able to explain our results as target substitution in consciousness by mask representation due to enhanced mask processing.     

Face the Beast and Fear the Face: Animal and Social Fears as Prototypes for Evolutionary Analyses of Emotion

This paper applies a functional-evolutionary perspective to fear in the context of encounters with animals and threatening humans. It is argued that animal fear originates in a predatory defense system whose function is to allow animals to avoid and escape predators. Animal stimuli are postulated to be differentially prepared to become learned elicitors of fear within this system. Social fears are viewed as originating in a dominance/submissiveness system. The function of submissiveness is to avert attacks from dominating conspecifics. Signs of dominance paired with aversive outcomes provide for learning fear to specific individuals. Data which in general are interpreted as supportive of this conceptualization are reviewed. To explain the mechanism behind the causal relationships suggested in the evolutionary analysis, an information-processing model is presented and empirically tested. It is argued that responses to evolutionary fear-relevant stimuli can elicit the physiological concomitants of fear after only a very quick, “unconsciousness,’ or preattentive stimulus analysis. Support for this notion is presented from backward masking studies where it is demonstrated that conditioned autonomic responses to fear-relevant stimuli can be elicited even with masked stimuli.     

Emotion-processing deficit in alexithymia.

College undergraduates were identified as alexithymic or control, based on their scores on the Toronto Alexithymia Scale (TAS; Taylor, Ryan, & Bagby, 1985). All subjects were presented standardized emotion-eliciting color slides for 6 s while facial muscle, heart rate, and skin conductance activity were recorded. Stimuli were presented a second time while subjects were asked to provide emotion self-reports using a paper-and-pencil version of the Self-Assessment Manikin (SAM; Lang, 1980) and to generate a list of words describing their emotional reaction to each slide. Consistent with the definition of alexithymia as a syndrome characterized, in part, by a deficit in the identification of emotion states, high TAS subjects supplied fewer emotion-related words than did controls to describe their response to the slides. Alexithymics also indicated less variation along the arousal dimension of the SAM, produced fewer specific skin conductance responses and showed less heart rate deceleration to the slides, regardless of category. No valence-related differences between alexithymic and control subjects were noted.     

The roles of stimulus novelty and significance in determining the electrodermal orienting response: interactive versus additive approaches

Two competing approaches for the roles of stimulus significance and novelty in determining orienting responses (ORs) were tested and compared. According to the first, ORs to significant stimuli are determined by sets and expectations and are relatively independent of the contrast between the test stimulus and preceding stimuli, whereas responses to nonsignificant test stimuli are products of a Sokolovian match/mismatch process. According to an alternative approach, novelty and significance contribute independently and additively to the OR. Stimulus significance and novelty were independently manipulated in two experiments, and the electrodermal component of the OR was measured while sequences comprising compound pictorial or verbal stimuli were presented. Each sequence included a test stimulus that was either significant or neutral and was preceded by several control stimuli. Novelty was manipulated by varying the contrast between the test and the control stimuli. The results revealing no interaction between stimulus significance and novelty were interpreted as supporting the theory proposed by Cati and Ben-Shakhar (1990).