Sensory information,fear level,and reactions to pain1

An experiment was conducted to investigate the conditions under which sensory information has beneficial versus detrimental value as preparatory information to assist individuals in coping with stress. Fourteen high fear and twelve low fear college women underwent exposure to the cold pressor test. Half of each fear group was provided with sensory information about the sensations produced by the cold pressor and half received a control message. Distress judgments made during the cold pressor showed (a) that sensory information effectively reduced distress for low fear women, but (b) sensory information exacerbated the distress of high fear women—at least during early portions of the cold pressor test. The data generally support Leventhal's (1979) perceptual-motor theory of emotion and have pragmatic implications for those persons who provide preparatory information to individuals anticipating a stressful encounter.     

Differential effect of ill-being and chronic stress on cradling behavior of first and multi-time parents

A preference for cradling infants on the left side has been demonstrated in women, as has a relation of reduced left-cradling and stress/negative affect. This relation has not yet been investigated in male participants. Due to less left-cradling in non-fathers compared to fathers it was suggested that fatherhood might have an influence on cradling behavior. The present study investigated the cradling preference of first- and multi-time parents before and after birth, and its relation to ill-being and stress. Results revealed that cradling behavior of first-time fathers was not different before and after the birth of the infant. Thus, fatherhood does not seem to have an acute influence on cradling behavior. Furthermore, cradling behavior of first- and multi-time parents was differentially influenced by ill-being and stress.These results present new information about the course of cradling preference from pregnancy to postpartum and indicate that the relation of cradling and ill-being/stress is more complex for parents than for non-parents.     

Cradling side preference is associated with lateralized processing of baby facial expressions in females

Women’s cradling side preference has been related to contralateral hemispheric specialization of processing emotional signals; but not of processing baby’s facial expression. Therefore, 46 nulliparous female volunteers were characterized as left or non-left holders (HG) during a doll holding task. During a signal detection task they were then asked to detect the emotional baby faces in a series of baby portraits with neutral and emotional facial expressions, presented either to the left or the right visual field (VFP). ANOVA revealed a significant HG × VFP interaction on response bias data (p < .05). Response bias was lowest when emotional baby faces were presented in the visual field of cradling side preference, suggesting that women’s cradling side preference may have evolved to save cognitive resources during monitoring emotional baby face signals.     

Effects of pre-learning stress on memory for neutral, positive and negative words: Different roles of cortisol and autonomic arousal

Stress can have enhancing or impairing effects on memory. Here, we addressed the effect of pre-learning stress on subsequent memory and asked whether neutral and emotionally valent information are differentially affected by specific stress components, autonomic arousal and stress-induced cortisol. Ninety-six healthy men and women underwent either a stressor (modified cold pressor test) or a control warm water exposure. During stress, participants showed comparable autonomic arousal (heart rate, blood pressure), while 60 percent showed an increase of cortisol (responders vs. 40 percent non-responders). Ten minutes after the cold pressor test neutral, positive and negative words were presented. Free recall was tested 1 and 24 h later. Overall, positive and negative words were better recalled than neutral words. Stress enhanced the recall of neutral words independently of cortisol response. In contrast, the free recall of negative words was enhanced in cortisol responders in the 1-h but not 24-h test which might suggest different effects of cortisol on consolidation and reconsolidation processes. Recall for positive words was unaffected by stress-induced cortisol. To summarize, (i) pre-learning stress can enhance memory for neutral words independently of cortisol and (ii) stress effects on memory for negative words appear to rely on stress-induced cortisol elevations, the absence of this effect for positive words might be at least partly due to differences in arousal evoked by positive vs. negative words.     

Amygdala functional connectivity is reduced after the cold pressor task

The amygdala forms a crucial link between central pain and stress systems. Previous research indicates that psychological stress affects amygdala activity, but it is less clear how painful stressors influence subsequent amygdala functional connectivity. In the present study, we used pulsed arterial spin labeling (PASL) to investigate differences in healthy male adults’ resting-state amygdala functional connectivity following a cold pressor versus a control task, with the stressor and control conditions being conducted on different days. During the period of peak cortisol response to acute stress (approximately 15–30 min after stressor onset), participants were asked to rest for 6 min with their eyes closed during a PASL scanning sequence. The cold pressor task led to reduced resting-state functional connectivity between the amygdalae and orbitofrontal cortex (OFC) and ventromedial prefrontal cortex, and this occurred irrespective of cortisol release. The stressor also induced greater inverse connectivity between the left amygdala and dorsal anterior cingulate cortex (ACC), a brain region implicated in the down-regulation of amygdala responsivity. Furthermore, the degree of poststressor left amygdala decoupling with the lateral OFC varied according to self-reported pain intensity during the cold pressor task. These findings indicate that the cold pressor task alters amygdala interactions with prefrontal and ACC regions 15–30 min after the stressor, and that these altered functional connectivity patterns are related to pain perception rather than cortisol feedback.     

Lateral asymmetry and tactile sensitivity

Weinstein found in 1963 that the left female breast is more sensitive to tactile stimulation than the right breast. Saling and Cooke in 1984 hypothesized that this asymmetry in breast sensitivity underlies the well-documented leftward bias in maternal cradling behaviour, which is independent of manual specialization. Our interest in the Saling and Cooke hypothesis led to an attempt to replicate Weinstein's 1963 study. His findings were not supported. Further, a review of the literature on the lateral distribution of cutaneous thresholds showed that there is little experimental support for the widely held belief that the left side of the body is uniformly more sensitive than the right.     

Stress effects on affiliation preferences among subjects possessing the type A coronary-prone behavior pattern

An experiment tested the hypothesis that when subjects who display the Type A coronary-prone behavior pattern are placed under stress, they prefer to wait for the stressful event with others, but desire to work under stress alone. One half of 25 Type A and 25 Type B (non-coronary-prone) subjects were told that they would receive painful electric shock while working on a mental task, while the other one half were told that they would receive subliminal stimulation. Both groups were then given the choice of waiting for the event with others or alone and the choice of working on the task alone, in the company of others, or in a leader-directed group. The results showed that Type As relative to Type Bs tended to wait in the company of others regardless of threat level, but displayed a marked preference to work alone under high threat. This decision to work alone was not influenced by waiting preference. Subsequent correlational studies showed that coronary patients (n = 40) reported a greater preference for working alone when under pressure than matched controls (n = 40), as did Type A college students (77% vs. 14% for Type Bs) when asked their preference within the context of the structured interview that is used to assess the Type A pattern. The significance of the findings for increasing the understanding of affiliative preferences and coronary-prone behavior are discussed.     

Foraging behaviour in domestic pigs (Sus scrofa): remembering and prioritizing food sites of different value

This experiment investigated whether domestic pigs can remember the locations of food sites of different relative value, and how a restricted retrieval choice affects their foraging behaviour. Nine juvenile female pigs were trained to relocate two food sites out of a possible eight in a spatial memory task. The two baited sites contained different amounts of food and an obstacle was added to the smaller amount to increase handling time. On each trial, a pig searched for the two baited sites (search visit). Once it had found and eaten the bait, it returned for a second (relocation) visit, in which the two same sites were baited. Baited sites were changed between trials. All subjects learnt the task. When allowed to retrieve both baits, the subjects showed no preference for retrieving a particular one first (experiment 1). When they were allowed to retrieve only one bait, a significant overall preference for retrieving the larger amount emerged across subjects (experiment 2). To test whether this preference reflected an avoidance of the obstacle with the smaller bait, 15 choice-restricted control trials were conducted. In control trials obstacles were present with both baits. Pigs continued to retrieve the larger bait, indicating they had discriminated between the two food sites on the basis of quantity or profitability and adjusted their behaviour accordingly when the relocation choice was restricted. This suggests for the first time that domestic pigs have the ability to discriminate between food sites of different relative value and to remember their respective locations.     

The Impact of Demand Characteristics on Brief Acceptance- and Control-Based Interventions for Pain Tolerance

The present analog study compared the effectiveness of an acceptance- and control-based intervention on pain tolerance using a cold pressor task, and is a partial replication and extension of the Hayes, Bissett et al. (Hayes, S. C., Bissett, R.T., Korn, Z., Zettle, R. D., Rosenfarb, I. S., Cooper, L. D., & Grundt, A. M. (1999). The impact of acceptance versus control rationales on pain tolerance. The Psychological Record, 49, 33-47) study. Our aim was to test the effects of a nonspecific source of therapeutic change within the context of ACT therapy. Otherwise healthy undergraduates (N = 20) were exposed to a cold pressor task before, immediately after, and 10 min following one of the two interventions. Half of the participants also were assigned to a high demand characteristic condition in which the experimenter maintained close physical proximity, eye contact, and placed subtle social pressure on participants to please the experimenter. The results showed that the most important factor influencing latency to withstand the cold pressor task was social pressure. The acceptance-based intervention was more subject to demand than the control strategy. Evaluative ratings of pain were unaffected by the demand manipulation. The current data suggest that demand characteristics can exert a significant positive impact on the outcome of therapeutic protocols. The implications of this view for acceptance- and control-based psychosocial interventions are discussed.     

Sympathetic reactivity in late pregnancy is related to labour onset in women

Stress regulation during pregnancy is considered to be connected to the timing of labour initiation. Although increasing knowledge is emerging on the regulation of parturition, there is currently no way to predict the start of spontaneous labour in women. The main aim of this study was to assess pain threshold and the sympathetic nervous system response to cold pain in relation to the onset of labour in healthy pregnant women. Ninety-three pregnant women were recruited and assessed for skin conductance (SC) activity during a cold pressor test in gestational week 38. Pain threshold and cold endurance were also measured and the results were compared with data obtained from hospital records. Seventy-four women had a spontaneous labour onset and a valid SC measurement. SC activity during the cold pressor test decreased significantly with the number of days left to spontaneous parturition. This may indicate a gradual decrease in sympathetic autonomic nervous system reactivity even during the last weeks of pregnancy. Measuring SC activity during mild stress provocation is a rapid and non-invasive means to study variation in sympathetic reactivity during pregnancy, and may be useful in research on stress regulation in pregnancy and its relation to labour initiation.     

Human left-sided cradling preferences for dogs

Photographs of men and women holding dogs were analyzed for side-holding preferences. A significant majority of women in dog-themed magazines held dogs on their left sides, similar to reports of women holding infants. Men did not show the same left-sided preference, which is also consistent with other studies. The implications of these results for various hypotheses about infant cradling behavior were discussed.     

Working memory performance after acute exposure to the cold pressor stress in healthy volunteers

Effects of acute stress exposure on learning and memory have been frequently studied in both animals and humans. However, only a few studies have focused specifically on working memory performance and the available data are equivocal. The present study examined working memory performance during the Sternberg item recognition task after exposure to a predominantly adrenergic stressor. Twenty four healthy subjects were randomly assigned to a stress group or a control group. The stress group was exposed to the cold pressor stress test (CPS; i.e. insertion of the dominant hand into ice water for 60s), while 37 °C warm water was used with the control group. Twenty minutes after the stress exposure, working memory performance was tested with the Sternberg item recognition task with three levels of cognitive load. Sympathetic nervous system and hypothalamic pituitary adrenocortical (HPA) axis activation during CPS, were assessed by measuring heart rate and salivary cortisol before and during (heart rate) or 30 min after (cortisol) the stress procedure. Exposure to the CPS test was associated with a significant increase in heart rate but no increase in salivary cortisol. Participants exposed to the stress procedure showed significantly shorter reaction times during trials with higher cognitive load but tended to show higher false alarm rates than control subjects. The present results indicate that exposure to CPS can be associated with signs of both enhanced and impaired working memory performance. The observed behavioral pattern might represent a form of streamlined information processing advantageous in a threatening situation.     

Pain perception to the cold pressor test during the menstrual cycle in relation to estrogen levels and a comparison with men

Animal and human research has shown that pain sensitivity changes during the menstrual cycle. This has sometimes been ascribed to hormonal variations. The aim of the present study was to examine how perception of pain, induced by the cold pressor test to the dominant hand, was related to gender and phases of the menstrual cycle. A repeated-meausres design was used, where twenty-two female students participated at two different phases of the menstrual cycle (days 2–4 and days 20–24). A control group of nineteen male students participated on two occasions, separated by a three week period. The cycle phase during which each woman began her participation was randomized. Pain was induced using the cold pressor test. Pain threshold was determined as the duration of time between when the subject first reported pain and exposure to the painful stimulus. Pain tolerance was determined as the duration of time until the subject withdraw her/his hand from the test water because the pain was too intensive. The results showed that men tolerated significantly greater pain than women. Women’s pain threshold was significantly higher during the second phase of the menstrual cycle. Systolic pressure was higher in men than women, increasing more in men in response to cold pressor testing than women. Further research, including measurments of plasma hormone levels during the menstrual cycle, is needed to clarify the role played by estrogens in pain perception.     

When left means right: an explanation of the left cradling bias in terms of right hemisphere specializations

Previous research has indicated that 70-85% of women and girls show a bias to hold infants, or dolls, to the left side of their body. This bias is not matched in males (e.g. deChateau, Holmberg & Winberg, 1978; Todd, 1995). This study tests an explanation of cradling preferences in terms of hemispheric specialization for the perception of facial emotional expression. Thirty-two right-handed participants were given a behavioural test of lateralization and a cradling task. Females, but not males, who cradled a doll on the left side were found to have significantly higher laterality quotients than right cradlers. Results indicate that women cradle on the side of the body that is contralateral to the hemisphere dominant for face and emotion processing and suggest a possible explanation of gender differences in the incidence of cradling.     

Anxiety mediates the effect of acute stress on working memory performance when cortisol levels are high: a moderated mediation analysis

Background: Anxiety is an aversive emotional state characterized by perceived uncontrollability and hypervigilance to threat that can frequently cause disruptions in higher-order cognitive processes like working memory. The attentional control theory (ACT) predicts that anxiety negatively affects the working memory system. Design: This study tested the association between anxiety and working memory after the addition of stress and measured the glucocorticoid, cortisol. To better understand this relationship, we utilized a moderated mediation model. Methods: Undergraduate students from a public university (N = 103) self-reported their anxiety levels. Participants first completed a short-term memory test. During and after a forehead cold pressor task (stress vs. control procedure) participants completed a working memory test. Salivary cortisol was taken at baseline and after the last working memory test. Results: Overall, acute stress had no effect on working memory. However, we found that anxiety levels mediated the influence of condition (stressed vs. control) on working memory, but only among those individuals who had high cortisol levels after exposure to acute stress, supporting a moderated mediation model. Conclusions: These results imply that activation of the hypothalamic–pituitary–adrenal axis was necessary for working memory impairment in anxious individuals. These results provide support for the ACT.     

Reduced emotional stress reactivity to a real-life academic examination stressor in students participating in a 20-week aerobic exercise training: A randomised controlled trial using Ambulatory Assessment

ObjectivesTo examine if a preventive 20-week aerobic exercise intervention (AET) can improve emotional stress reactivity during real-life stress.DesignRandomised controlled trial; within-subject design.MethodSixty-one inactive students were randomly assigned to a waiting control and an AET group. To capture the situation-specific, intra-individual data in real life, electronic diaries were used. Participants reported their moods and perceived stress (PS) repeatedly over two days during their daily routines pre- and post-intervention. The pre-intervention baseline assessment was scheduled at the beginning of the semester, and the post-intervention assessment was scheduled at a real-life stressful episode, an academic examination. For the aerobic fitness assessment, both groups completed a cardiopulmonary exercise test on the treadmill before and after the intervention. Multilevel models (MLMs) were conducted to compare within- and between-subject associations.ResultsSignificant emotional stress reactivity was evident in both groups during all assessment periods. However, participants in the AET group showed lower emotional stress reactivity compared with their control counterparts after the 20-week training programme during the real-life stress episode (the academic examination).ConclusionsAET conferred beneficial effects on emotional stress reactivity during an academic examination, which is likely an extremely stressful real-life situation for students.AET appears to be a promising strategy against the negative health effects of accumulated emotional stress reactivity.     

Impaired memory retrieval correlates with individual differences in cortisol response but not autonomic response

Stress can enhance or impair memory performance. Both cortisol release and sympathetic nervous system responses have been implicated in these differential effects. Here we investigated how memory retrieval might be affected by stress-induced cortisol release, independently of sympathetic nervous system stress responses. Thirty-two healthy participants (16 women) learned emotionally arousing and neutral words. One hour later, half of the participants underwent a stressor (cold pressor test) and the other half, a control warm water exposure, both followed by a delayed free recall task. The stressed participants were split into those who did (responders, N = 8) and those who did not (nonresponders, N = 6) show a cortisol response. Both responders and nonresponders showed comparable sympathetic nervous system activity (skin conductance level) during the cold pressor. The cortisol responders recalled significantly fewer words compared to nonresponders, and compared to control participants; this effect was most pronounced for moderately arousing words (compared to highly arousing and neutral words). These results suggest that individual differences in cortisol reactivity affect memory retrieval performance, and help to explain the differential effects of stress on memory.     

Cardiovascular and neurohumoral responses to behavioral challenge as a function of race and sex

Cardiovascular and hormonal responses to a structured interview, an electronic video game, a cold pressor test, and exercise on a bicycle ergometer were assessed in eighty-three 25- to 44-year-old normotensive Black and White men and women. Blacks showed significantly greater diastolic blood pressure (DBP) responses than Whites during the cold pressor test, which were not accounted for by an increase in plasma catecholamines. Exercise produced reliably greater systolic blood pressure (SBP) increases in Black women than in Black men or White women. Men showed significantly greater SBP and DBP changes than women during the video game. These findings suggest that the pattern of physiological reactivity elicited by challenge is related to the race and sex of the subjects.     

Cognitive discrimination in brain-damaged adults: color vs form preference

The relative preference of color, form, and other dimensions as the basis for discrimination between stimuli has been investigated in a variety of normal and language-impaired populations. In aphasic adults, previous studies have been contradictory, and no studies of non-aphasic, brain-damaged adults have been reported. In this study color vs form preference was examined in 20 left brain-damaged, aphasic adults, 20 right brain-damaged non-aphasic adults, and 20 control subjects. Significant differences were found among all groups, with preference of color over form greatest for left brain-damaged subjects, followed by right-damaged and control subjects.     

性别比与童年经济状况对女性长短期择偶偏好的影响：“暖男”需求变化的进化分析

基于进化领域的生命史理论,采用两种实验启动的途径探讨性别比、童年经济状况和女性长短期择偶偏好间的关系。结果表明：女性在长期择偶中更为重视男性的“好爸爸”和“好资源”,在短期择偶中更为重视男性的“好基因”;性别比在女性长期择偶的“好爸爸”偏好上具有显著主效应,在“女多男少”情境下女性对“好爸爸”的偏好水平会较“男多女少”时明显提高;性别比和童年经济状况在女性长期择偶“好爸爸”偏好上的交互效应显著：童年贫穷女性在“女多”情境下会明显提高对长期择偶“好爸爸”的偏好水平,童年富裕女性在性别失衡情境下对长期“好爸爸”的偏好保持相对稳定。