Sex differences and bilateral electrodermal activity

The present study was aimed at replicating the results of a previous work on sex differences and electrodermal asymmetry from our laboratory (Román,et al. 1987). Skin conductance was bilaterally recorded in a sample of 44 dextral volunteers (22 males and 22 females) during a stimulus-free period, and the performance of two tasks (verbal and spatial). Subjects were grouped into two groups of right-hand and left-hand dominance in their electrodermal responses (EDRs) in accordance with their laterality coefficient scores at rest. During the tasks subjects appeareed clearly differentiated by their lateralization in the magnitude and frequency of EDRs independently of gender: right-hand responders showed higher electrodermal activity on their right hand, while left-hand responders showed higher electrodermal activity on their left hand. Sex differences were not observed within each responsiveness pattern. The orientation of phasic electrodermal changes remained constant throughout the different conditions.     

An investigation of bilateral asymmetries in electrodermal activity

Research in cerebral laterality supports the idea that functional differences between the left and right hemispheres exist with respect to cognitive style and perceptual ability. Related research, which has examined autonomic nervous system (ANS) correlates of cerebral laterality, suggests that a component of the ANS, electrodermal activity (EDA), is also lateralized. Some findings in the literature report the occurrence of bilateral asymmetries in phasic and tonic EDA as a function of a left or right hemisphere preference for information processing. This experiment used normal male subjects who were either left or right movers in a test of Conjugate Lateral Eye Movement (CLEM). This selection procedure served to maximize a subject’s preference for either a right or left hemisphere mode of information processing. Bilateral EDA was recorded continuously while subjects performed a visual recognition task using word (left hemisphere) and shape (right hemisphere) stimuli. The data do not support the contention that performance on a procedure chosen to selectively activate a given hemisphere elicits asymmetric tonic and/or phasic EDA. The results show no significant difference in the frequency of elicited skin conductance responses under either of the experimental conditions. Bilateral tonic EDA rose continuously over time and did not vary in either hand as a function of task. The present results fail to offer support for either of the hypotheses which argue for I) increased contralateralexcitation with selective hemispheric activation, or 2) increased contralateralinhibition of the EDR with hemispheric arousal.     

Sex differences in the activity level of infants1

A gender difference in motor activity level (AL) is well established for children, but questions about the existence and nature of an infant sex difference remain. To assess these questions, we applied meta‐analytic procedures to summarize 46 infancy studies comprising 78 male–female motor activity comparisons. Our results showed that, as with children, male infants were more active than females. Objective measures of infant AL estimated the size of this difference to be 0.2 standard deviations, though subjective parent‐report measures estimated the difference to be smaller. We argue that this early sex difference in activity level is biologically based. However, socialization processes, such as gender‐differentiated expectations and experiences, in conjunction with further sex‐differentiated biological developments, amplify this early difference to produce the larger gender differences in activity found during childhood. Copyright © 1999 John Wiley & Sons, Ltd.     

Smoking,personality, and imagery preference in Relation to spontaneous bilateral electrodermal activity

Effects of smoking on spontaneous bilateral skin conductance were studied as a consequence of interactions with set and setting. Bilateral skin conductance was recorded in six men and six women who smoked and an equal number of nonsmokers on two different days. On the first day, spontaneous electrodermal activity was recorded before and after a 10-minute rest period during which half the smokers smoked a cigarette. On the second day, one week later, spontaneous activity was again recorded before and after a 10-minute rest period during which the remaining smokers smoked a cigarette. Nonsmokers did not smoke at any time. Following smoking there was a significant negative correlation between a preference for visual over nonvisual imagery and spontaneous skin conductance responsivity in the left as compared to the right hand. Correlations were significantly different in smokers and nonsmokers. Smokers showed significantly greater preferences for either visual or nonvisual imagery than nonsmokers. Nonresponding nonsmokers were higher on the psychoticism (P) scale of the Eysenck Personality Questionnaire (EPQ) than responding nonsmokers. Smokers scored higher on P than nonsmokers. Interactions between personality, cognitive style, and the experimental situation, set, and setting were discussed in relation to the arousing effects of nicotine.     

Effects of question type and experimenter position on bilateral differences in electrodermal activity and conjugate lateral eye movements

28 dextral males participated in a within-subjects experiment which tasted for the effects of question type (verbal versus spatial) and experimenter-position (in front of or behind the subject) on direction of conjugate lateral eye movements (LEMs) and bilateral differences in skin conductance responses (SCRs). Question dependent asymmetries were observed for LEM direction but not for SCR magnitude. Experimenter-position had no significant effect. The results for LEM direction are consistent with the hypothesis linking eye movements to the left or right with activation of the cerebral hemisphere contralateral to the direction of gaze. The results for SCR magnitude, given certain assumptions, can be reconciled with a hemispheric model of contralateral excitatory control of that system.     

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 Gray's anxiety theory.     

Sex and menstrual cycle differences in the habituation and spontaneous recovery of the electrodermal orienting reaction

Sex and menstrual cycle differences have been widely observed in electrodermal activity. The aim of this study was to investigate these differences in the electrodermal orienting reaction employing a habituation-spontaneous recovery procedure. According to previous research it was predicted that men and preovulatory women should show higher electrodermal responses, higher skin conductance levels, and slower habituation rates. Thirty-two subjects (16 males and 16 females) were presented with two series of tones, 10 in the first series and eight in the second, with a 4-min rest period between the two series. Half of the subjects received the same 5-sec tone (80 dB, 1000 Hz) in each presentation while the other half received 80-dB, 5-sec tones which varied randomly in frequency (100, 500, 1000 Hz). Women were divided into two groups; preovulatory (n = 7) and postovulatory (n = 8) according to their answers to a retrospective questionnaire. The mean response amplitude was higher in the group of males, who habituated later than females. Postovulatory women showed lower orienting reactions in the first series, and habituated faster than did preovulatory women in the two series. There were neither significant differences between males and females, nor between preovulatory and postovulatory women in tonic conductance levels. These results support the existence of greater electrodermal reactivity in males and in preovulatory women.     

Behavioral inhibition and electrodermal activity during deception

We tested the assumption that the act of inhibiting ongoing behavior requires physiological work. In a guilty knowledge test (GKT) paradigm, subjects were induced to attempt to deceive the experimenter on two separate occasions while electrodermal activity was measured. For 20 of the 30 subjects, overt behaviors (changes in eye movement and facial expression) were recorded during the second GKT. Results indicated that the incidence of behaviors decreased during their deceptive responses. This behavioral inhibition coincided with increases in skin conductance level. In addition to suggesting nonverbal correlates of deception, the results indicate that long-term behavioral inhibition may be a factor in psychosomatic disease.     

Sex differences in brain activity related to general and emotional intelligence

The study investigated gender differences in resting EEG (in three individually determined narrow alpha frequency bands) related to the level of general and emotional intelligence. Brain activity of males decreased with the level of general intelligence, whereas an opposite pattern of brain activity was observed in females. This difference was most pronounced in the upper-alpha band which is related to semantic memory processes. It was further found that highly intelligent males displayed greater decoupling of frontal brain areas, whereas highly intelligent females showed more coupling between frontal and parietal/occipital brain areas. Similar, but less significant differences were observed for the two area scores of strategic and experiential emotional intelligence. It appears that males and females have different resting EEG correlates of IQ.     

Pre-extinction of sensory preconditioned electrodermal activity

In the present study, sensory preconditioning of human electrodermal activity was demonstrated. In the first phase of the experiment, two pairs of neutral pictures of human faces were presented (A/B and C/D) sequentially. In the second phase, one picture of one pair was immediately followed by an electrocutaneous stimulus (B+), and one picture of the other pair was not (D-). In the third phase the other picture of each pair (A and C) was tested. The effect of A and C alone presentations (pre-extinction) between the first and the second phase was investigated. When only those participants that showed reliable B+/D- differentiation were considered, the extinction group did not show stronger conditioned electrodermal activity to A than to C, whereas the control group did. These findings suggest that sensory preconditioning of anticipatory/preparatory responding only occurs when the pre-conditioned stimulus (A) actually predicts the conditioned stimulus (B).     

Sex differences,sex-role orientation,and reward allocations

In study 1, 52 male and 52 female undergraduates allocated rewards to pairs of children for their performances in team and competitive situations. Males allocated rewards more equitably, especially when allocating to boys in competition, while females allocated rewards more equally. Boys, but not girls, who did more work received more rewards than their partner; and children with greater work inputs under competitive conditions received more rewards than children in team conditions. In study 2, the sex-role orientation of 60 college students was found to be related to their reward allocations. Males and females with a masculine sex-role orientation allocated rewards equitably, while individuals with a feminine sex-role orientation allocated rewards equally. Results indicated that sex and situational differences in reward allocations are affected by sex-role orientation and differential socialization practices by adults.Portions of study 1 were presented at the Midwestern Psychological Association Meeting, Chicago, May 1978.     

Bilateral electrodermal activity in waking man

Skin conductance responses were examined bilaterally in a group of 14 normal subjects. Twelve of them were right-handed and two were left-handed. All right-handed subjects exhibited asymmetry in skin conductance level and in skin conductance response during verbal-numerical and visual-imagery tasks. With the visual activity, larger responses were found in the left hand, while during the verbal task, larger responses were recorded from the right hand. The results were interpreted as evidence of hemispheric asymmetry of the electrodermal activity orienting response control mechanisms. More ipsilateral control for the right hand is predicted.     

Reduced electrodermal activity in psychopathy-prone adolescents

This study tests the hypothesis that psychopathy-prone adolescents show reduced anticipatory skin conductance responding. Electrodermal activity was recorded while participants anticipated and responded to a 105 dB signaled or unsignaled white-noise burst. Using an extreme groups design, the authors used Child Psychopathy Scale (D. R. Lynam, 1997) scores from a community sample of 335 male adolescents (age 16) to form control (n = 65) and psychopathy-prone (n = 65) groups. Significantly more psychopathy-prone participants were nonresponders in the signaled anticipatory (p = .014), signaled responsivity (p = .037), and unsignaled responsivity (p = .003) conditions compared with controls. Anticipatory hyporesponsivity of psychopathy-prone adolescents similar to the electrodermal hyporesponsivity found in psychopathic adults suggests that this autonomic impairment is present by adolescence and may predispose individuals to adult psychopathy.     

Sex differences in brain activity, personality and intelligence: a test of arousability theory

This report describes empirical tests of the theory that females have higher levels of behavioural and cerebral arousal than males and that these differences cause higher neuroticism scores in females, as well as lower female psychoticism scores and lower scores for females on the Gsar factor of intelligence. Data were obtained from 76 subjects, with equal numbers of males and females and with all adult ages represented. EEG responses to auditory stimulation were quantified in terms of the ‘amplitude, ‘rate of change of amplitude and ‘sweep variability factors obtained from a principal components analysis (PCA). Gf, Gc and Gsar intelligence scores were obtained from a PCA of sub-tests from the Wechsler Adult Intelligence Scale plus Ravens Advanced Progressive Matrices test. Personality differences were evaluated using the Neuroticism and Psychoticism scales of the Eysenck Personality Questionnaire (EPQ). Bivariate hypotheses relating sex to the arousal, intelligence and personality variables were confirmed. A PCA demonstrated that sex, neuroticism, Gsar, wakefulness and high frequency EEG activity all have high loadings on a common factor. These results are consistent with expectations generated by the cerebral arousability theory of personality and intelligence.     

Sex differences in functional brain activation during a lexical visual field task

Functional MRI was used to investigate sex differences in brain activation during a paradigm similar to a lexical-decision task. Six males and 6 females performed two runs of the lexical visual field task (i.e., deciding which visual field a word compared with a pseudoword was presented to). A sex difference was noted behaviorally: The reaction time data showed males had a marginal right visual field advantage and women a left visual field advantage. Imaging results showed that men had a strongly left-lateralized pattern of activation, e.g., inferior frontal and fusiform gyrus, while women showed a more symmetrical pattern in language related areas with greater right-frontal and right-middle-temporal activation. The data show evidence of task-specific sex differences in the cerebral organization of language processing.     

Sex differences in memory estimates,revisited

207 undergraduate students (95 men and 112 women) representing all four years in college provided estimates of memory performance before and after a recall task involving 80 stimuli (41) pictures and 40 words). The study was intended as a replication of the work of Ionescu in 2000 wherein men underestimated their performance on the picture items and women underestimated their performance on the words. No sex differences were found for correct recall totals, recall for pictures, recall for words, and total prerecall performance estimates. Although both men and women underestimated their pre- and postrecall performance, women underestimated their postrecall performance more than men. More importantly, men underestimated their performance on recall of pictures, whereas women underestimated their performance on the word items, thereby validating prior results with a larger sample. The possible bases for this phenomenon are still not clear.     

Sex differences in rats' response to novelty measured by activity and preference

Rats were familiarized to one compartment of a test box and then given access to this and a novel compartment. Females spent more time in the novel compartment than males did and this difference was found to be independent of a possible difference in familiarity with the familiar compartment arising from the females' higher frequency of ambulating and rearing with sniffing during familiarization. This is evidence of a sex difference in response to novelty independent of activity differences. Females also had shorter approach latencies to the novel compartment. These sex differences could reflect differences in either fearfulness or curiosity.