The influence of sex, gender, self-discrepancies, and self-awareness on anger and verbal aggressiveness among U.S. college students.

Among a sample of 445 U.S. college students, the authors examined the extent to which individual differences (e.g., sex, gender, self-discrepancies, self-awareness) explained anger tendencies and verbal aggressiveness. Regression analyses showed that (a) the tendency to repress anger (anger-in) was explained by masculinity, desire to be masculine, and public self-awareness, R2 = .19, F(11, 433) = 8.44, p < .001; (b) the tendency to express anger (anger-out) was explained by sex, masculinity, and public self-awareness, R2 = .17, F(11, 433) = 7.38, p < .001; and (c) willingness to be verbally aggressive was explained by sex, femininity, and private self-awareness, R2 = .32, F(11, 433) = 16.94, p < .001. In addition, different types of individual difference variables accounted for anger tendencies and verbal aggressiveness across sex and gender categories, suggesting that anger and verbal aggressiveness may be driven by different psychological processes across types of participants.

Cortisol and vagal tone responses to competitive challenge in preschoolers: associations with temperament.

Sixty-one 3- to 5-year-old nursery school children participated in a study of tempera ment and stress responses to competition. Each child individually participated in a competition against a familiar adult experimenter to determine who would win enough games to receive a prize. After initially winning three games (Win Period), the children lost the next three games (Lose Period), before winning the final games and receiving the prize. Salivary cortisol, vagal tone, affect and turn-taking behavior were measured in response to the competition and examined in relation to child temperament using a teacher-report version of the Child Behavior Questionnaire. Behavioral measures indicated that the procedures were emotionally engaging and the threat of losing was aversive. Surgency (extroversion) was positively correlated with positive affect during Win periods and tense/angry affect during the Lose period of the competition. Vagal tone decreased as the children began to play against the adult and children who were more tense/angry while losing showed additional suppression of vagal tone when they began to lose the competition. Most of the children did not show a cortisol response to the competition; however, the 15% who increased cortisol (responses >1 SD of classroom baselines) were described by teachers as more surgent and lower in effortful control. All but one of these children who increased in cortisol was male. Cortisol responsive children also displayed higher levels of tense/angry affect during the Lose period. Surgent, extroverted children appear to be vulnerable to competition stress.

Behavioral and physiological responsivity, sleep, and patterns of daily cortisol production in infants with and without colic.

To describe the behavioral and physiological responses associated with colic, the responses of 20 two-month-old infants with and 20 without colic were studied during a physical examination. Parents kept a diary of infant behaviors (including crying and fussing) for 3 days following the visit. Using Wessel, Cobb, Jackson, Harris, & Detwiler criteria, colic was defined as fussing/crying for 3 hr or more on each of the 3 days. Behavioral data coded by "blind" observers showed that during the physical exam, colic infants cried twice as much, cried more intensely, and were more inconsolable than were control infants. Despite these behavioral differences, heart rate, vagal tone, and cortisol measures indicated no appreciable difference in physiological responsivity for the two groups. At home, parents collected saliva cortisol samples at wakeup, midmorning, midafternoon, and evening for 2 days. In a finding similar to that shown by the laboratory data, the colic and control infants did not have different levels of daily average cortisol. These laboratory and home data provide no evidence of greater responsivity in the physiological substrate of difficult temperament for colic infants and are consistent with evidence of similarity in temperament once colic is resolved. At home, compared with control infants, colic infants did display a blunted rhythm in cortisol production. By diary, they also slept about 2 hr less per day than did control infants. Nighttime sleep was still significantly different when fussing/crying was statistically controlled. These data suggest that colic might be associated with a disruption or delay in the establishment of the circadian rhythm in activity of the hypothalamic-pituitary-adrenocortical axis and associated sleep-wake activity.

The start of a new school year: individual differences in salivary cortisol response in relation to child temperament.

Noon and evening salivary cortisol levels were examined in 70 elementary school children during the 1st week of a new school year. Samples were obtained on the 1st and 5th days of school and on weekend days. Delta cortisol scores were created to measure the change in children's levels on initial school days relative to weekend days. Temperament was assessed using Rothbart's Child Behavior Questionnaire, a parent report instrument. The three dimensions of surgency or extroversion, negative affectivity, and effortful control were examined. Positive correlations were obtained with Day 1 delta cortisol for negative affectivity and Day 5 delta cortisol for surgency. Contrary to the expectation that internalizing aspects of temperament (shyness, fearfulness) would be associated with larger increases in cortisol to the novelty and challenge of a new school year, these data indicate that larger increases in cortisol were observed in more extroverted children.

Individual differences in prefrontal activation asymmetry predict natural killer cell activity at rest and in response to challenge.

Reliable individual differences in electrophysiological measures of prefrontal activation asymmetry exist and predict dispositional mood and other psychological and biological indices of affective style. Subjects with greater relative right-sided activation report more dispositional negative affect and react with greater intensity to negative emotional challenges than their left-activated counterparts. We previously established that such individual differences in measures of prefrontal activation asymmetry were related to basal NK function, with left-activated subjects exhibiting higher levels of NK function than right-activated subjects. The present study was designed to replicate and extend these earlier findings. Subjects were tested in five experimental sessions over the course of 1 year. During the first two sessions, baseline measures of brain electrical activity were obtained to derive indices of asymmetric activation. During sessions 3 and 4, blood samples were taken during a nonstressful period in the semester and then 24 h prior to the subjects' most important final examination. During session 5, subjects were presented with positive and negative film clips 30 min in duration. Blood samples were obtained before and after the film clips. Subjects with greater relative right-sided activation at baseline showed lower levels of basal NK function. They also showed a greater decrease in NK function during the final exam period compared to the baseline period. Subjects with greater relative left-sided activation showed a larger increase in NK function from before to after the positive film clip. These findings indicate that individual differences in electrophysiological measures of asymmetric prefrontal activation account for a significant portion of variance in both basal levels of, and change in NK function.

Cortisol levels of young children in full-day childcare centers: relations with age and temperament.

Cortisol levels of 70 children, aged 39-106 months, were sampled at home and at their full-day childcare centers at two times of day, mid-morning and mid-afternoon. Parents and teachers completed questionnaires assessing child temperament (negative affectivity, surgency or extroversion, and effortful control) and aggressive behavior. The results replicated a previous study showing increases in cortisol levels over the day at childcare for preschool-aged children, while home levels followed the expected circadian decrease in cortisol from morning to afternoon for most children regardless of age. At childcare, 3- and 4-year olds were more likely to show elevations in cortisol by mid-afternoon than were older children. Controlling statistically for age, shyness for boys, and poor self-control and aggression for both sexes were associated with increases in cortisol over the day at childcare. The results suggest that younger children and those with more immature social skills may frequently experience elevations in cortisol as the day progresses in group care contexts.

Startle potentiation by threat of aversive stimuli and darkness in adolescents: a multi-site study.

In recent years, the startle reflex has become an exciting new tool to investigate affective responses to aversive stimuli in humans. The popularity of this methodology is largely based on the substantial amount of animal research available on this topic. Several procedures have been developed to examine startle potentiation in humans, but most studies have been carried out in adults and may not be appropriate for children or adolescents. The present study is a multi-site project (Yale University, Harvard University, and the University of Minnesota) investigating two new procedures to examine the potentiation of startle in adolescents. The subjects were 50 male and female aged 13-17 years old. One procedure examined fear-potentiated startle to the threat of an unpleasant airblast directed to the larynx. The second examined the facilitation of startle in darkness. Potentiation was found using each procedure and the degree of potentiation was similar across laboratories. These results suggest that both the threat of an airblast and darkness can reliably be used to examine startle potentiation in young subjects.

Dampening of the cortisol response to handling at 3 months in human infants and its relation to sleep, circadian cortisol activity, and behavioral distress.

The decrease in responsiveness of the hypothalamic-pituitary-adrenocortical (HPA) system is marked over the first months of life. Seventy-eight healthy infants (44 girls), 7 to 15 weeks old, were given a laboratory mock physical examination. Salivary cortisol samples were collected pre- and postexamination and at home. Behavioral state during the examination and home sleep/wake activity were measured. Subjects younger than 11 weeks showed an increase in pre- to postexamination cortisol, while older subjects did not. Further, there was no decrease in behavioral distress to the examination with age. Infants who showed an early- morning peak (EMP) in home cortisol levels were significantly older and were likely to be those who slept through the night. However, the presence of an EMP was not associated with a lack of cortisol response to the examination. The decrease in cortisol responsiveness witnessed around the age of 3 months is presumably due to other processes associated with age, and not with the expression of the day-night rhythm in basal cortisol.

Manipulating affective state using extended picture presentations.

Separate, extended series of positive, negative, and neutral pictures were presented to 24 (12 men, 12 women) undergraduates. Each series was presented on a different day, with full counterbalancing of presentation orders. Affective state was measured using (a) orbicularis oculi activity in response to acoustic startle probes during picture presentation, (b) corrugator supercilii activity between and during picture presentation, and (c) changes in self-reports of positive and negative affect. Participants exhibited larger eyeblink reflex magnitudes when viewing negative than when viewing positive pictures. Corrugator activity was also greater during the negative than during the positive picture set, during both picture presentation and the period between pictures. Self-reports of negative affect increased in response to the negative picture set, and self-reports of positive affect were greatest following the positive picture set. These findings suggest that extended picture presentation is an effective method of manipulating affective state and further highlight the utility of startle probe and facial electromyographic measures in providing on-line readouts of affective state.