Janick Naveteur

Individual differences in electrodermal activity as a function of subjects' anxiety

The present study examines the relationships between electrodermal activity (EDA) and anxiety in an attention demanding task, by looking at the neuropsychology of individual differences. 261 normal volunteer female students completed the Cattell anxiety form, and only subjects with extreme anxiety scores (deciles 0, 1 and 2 on the one hand, N = 22; deciles 9 and 10 on the other hand, N = 24) were retained. Subjects were presented a set of 16 stimuli (8 neutral and 8 emotional slides) in a randomized order (different for each subject), of 35 msec and 1 sec duration and a randomized inter-stimuli time of average 45 sec. Skin conductance levels (SCLs), interstimuli spontaneous fluctuations (SSCRs), skin conductance response (SCR) amplitudes and electrodermal latencies were recorded, as well as skin temperature (ST). Highly anxious subjects showed significantly lower SCLs, lower SCR amplitudes, fewer interstimuli SSCRs and longer latencies than subjects with low anxiety, whereas ST did not differ between groups. These results, showing that in normal subjects there are individual electrodermal differences as a function of trait-anxiety scores, are discussed both in terms of individual differences in self-regulatory neural processes and in reference to Grays anxiety theory.

Diurnal variations of tonic electrodermal activity.

Diurnal variability of skin conductance level (SCL) was examined in two complementary experiments, simultaneously with variability of skin temperature (ST) and that of simple reaction time (RT) which was recorded as a behavioural index of arousal. In Experiment I, 6 subjects spent 6 days in the laboratory in homogeneous conditions. Three recording sessions, each lasting 2 h, began, respectively, at 9:00 a.m. (morning), 1:00 p.m. (afternoon) and 5:00 p.m. (evening). Results indicated that SCL increased linearly throughout the day. Experiment II was undertaken to test whether this effect could still be observed in more heterogeneous conditions. Subjects (n = 12) attended to their own activities between the two 30-min sessions beginning, respectively, at 9:30 a.m. and 6:00 p.m. during a single experimental day. Again, SCL was higher in the evening than in the morning. In both experiments the SCL pattern seemed to be asynchronous with ST and RT variations. Taken as a whole, these data bring additional evidence of temporal electrodermal variation, a phenomenon which should be further taken into account in EDA research.

Anxiety, emotion and cerebral blood flow

Regional cerebral blood flow was measured by the xenon inhalation technique using a DSPECT system, during neutral and emotional auditory stimulations. Subjects were 10 high and 10 low trait anxiety, right-handed females. State anxiety was retrospectively assessed. Results indicated a lower rCBF in the high trait or state anxiety subjects who presented also a global rCBF asymmetry in the right > left direction. Additionally, the emotional content of the stimuli interacted significantly with the side of the brain in the thalamic area.

Influence of eye orientation on pain as a function of anxiety

&NA; The effect of eye orientation on pain was investigated as a function Of the stimulus intensity and the subjects anxiety. Right‐handed female subjects received sequences of electric shocks gradually increasing in intensity. Unpleasantness threshold, pain threshold, tolerance threshold and pain range were obtained when eyes were directed towards a target LED situated in the direction of, or away from, the source Of stimulation, in the ipsior contralateral hemispace. Directing the eyes ipsilaterally to the stimulated hand yielded a lower unpleasantness threshold when the right hand was stimulated. No significant effect was observed in high trait anxiety subjects. These results are interpreted in terms of hemispatial attention bias. Moreover, an ipsilateral eye Orientation increased pain range but this effect reversed in the highest state anxiety subjects. These latter observations could reflect the interacting influences of both spatial attention and state anxiety in selecting the processing mode of painful stimuli.

Emotional stimuli in rapid serial visual presentation

Rapid serial visual presentations were used to investigate the processing of emotional and neutral words: Immediate recall and repetition blindness, i.e., the difficulty in detecting or reporting that a same stimulus has been repeated within a stream. In Experiment 1, using streams of words, recall performance proved to be higher for emotional items than for neutral ones and repetition blindness appeared stronger for emotional than for neutral words. In Experiment 2, two target words were displayed among strings of symbols and the lag (i.e., the number of stimuli intervening between the repeated words) was manipulated. A stronger repetition blindness for emotional words occurred at lag 1, reinforcing findings of Experiment 1. Two additional experiments were conducted to strengthen the emotional effects found. Results, discussed in the framework of the type‐token account, support the idea that the emotional load influences early stages of processing.

The effect of eye orientation on slowly increasing pain

The present study investigated the influence of eye orientation upon the experience of pain. Quasi continuous electrocutaneous stimuli which slowly increased in intensity were delivered to 32 healthy females volunteers. Participants were instructed to direct the eyes at locations that were ipsilateral or contralateral to the stimulated hand. Unpleasantness threshold and pain threshold were significantly higher when the eyes were oriented ipsilateral towards the stimulated hand. In a second experiment phase, the pain intensity increased until tolerance. There was no effect of eye orientation upon pain threshold and tolerance. Results of the first experimental part are in line with the counterintuitive idea that selective monitoring reduces pain distress. The lack of significant results in the second experiment phase is discussed in terms of statistical power and a change in coping induced by the expectation of high intensity pain.

CUTANEOUS THRESHOLDS AND ANXIETY: INFLUENCE OF EYE ORIENTATION AND LATERAL ASYMMETRY

This study investigated the combined influence of anxiety and eye orientation on cutaneous thresholds. The relationship between anxiety and the lateral differences was also examined. Right-handed subjects of low and high trait anxiety received weak electric shocks on either hand. Cutaneous thresholds were recorded when eyes were directed towards or away from the stimulated area. State anxiety was retrospectively assessed. As compared to a contralateral eye orientation, directing the eyes ipsilaterally to the stimulated area yielded lower thresholds for subjects low in trait anxiety. This effect was not observed for subjects high in trait anxiety. The benefit of the ipsilateral orientation was higher for subjects with lower state-anxiety scores as well. Besides, subjects low in trait anxiety presented a left-hand advantage which was not shown by those high in trait anxiety. The left-right difference in thresholds was also positively correlated with state anxiety. The eye orientation results are discussed in terms of anxiety-induced modification of spatial attention and the differential hand sensitivity findings in terms of hemispheric specialization.

Electrodermal asymmetry and vigilance in negative emotion, anxiety and stress

Bilateral electrodermal levels and responses were recorded during an emotional and neutral slide projection in high and low trait anxiety subjects. Half of the subjects of each group received reassuring instructions the other half received stressful instructions. Levels were more symmetrical in anxious subjects but asymmetry was not influenced by instruction type. In contrast, responses were more symmetrical in anxious subjects, were more symmetrical under stressful instructions but were more asymmetrical to the emotional than the neutral slides.

Electrodermal level asymmetry in a unilateral brain-damaged patient

The purpose of this article is to report on a patient with right frontal damage who exhibited a strong left > right asymmetry of skin conductance levels (SCLs). Comparison with a control group indicates that this asymmetry resulted only from a higher SCL on the left hand. Such a result suggests that the frontal lesion has induced a contralateral disinhibition and is consistent with the idea of a contralateral inhibitory control of tonic electrodermal activity in the case of a healthy hemisphere. Peripheral factors, such as sweating or temperature seem unrelated to the SCL asymmetry and a possible influence of motor weakness is also rejected following comparison with a second patient who presented the same motor disorder without atypical SCL asymmetry. In contrast to SCLs, no asymmetry in skin conductance response amplitudes was observed in the former patient. This discrepancy is in line with previous observations showing that tonic and phasic EDA could depend on different neurophysiological controls.