Behavioral and Physiological Consequences of Crowding in Humans1

The purpose of this study was to investigate the effects of crowding on human performance. Results generally supported the hypothesis that crowding acts as a stressor which may be mediated by overarousal. Moderate decrements in complex but not simple task performance were found for crowded subjects as compared to uncrowded controls. Poorer performance on a group cooperation task and less tolerance for frustration as an aftereffect of the crowded experience were reported. Crowded subjects in comparison to controls also exhibited significant elevations in blood pressure and pulse rate and manifested additional behavioral indices of stress, which included greater behavioral stereotypes, increased defensive postures, more remarks toward the door of the experimental room, and self reports of greater discomfort and hostility.     

Psychophysiological reactivity to mental arithmetic stress in black and white normotensive men

Racial differences in physiological responses to a behavioral stressor were examined. Thirty-four Black and 42 White male normotensives 34 to 55 years old (mean age = 43.01 years) performed a mental arithmetic task while blood pressure, heart rate, and skin conductance were recorded. Compared to Whites, Blacks had significantly higher baseline diastolic blood pressure (77.93 mm Hg vs. 73.11 mm Hg) and lower skin conductance levels (11.08 microS vs. 12.25 microS). These effects persisted during performance of the mental arithmetic task. However, when baseline differences were covaried, there were no significant physiological effects associated with the task. Analysis of changes in response levels from baseline revealed a nonsignificant trend for Whites to show greater increases in systolic blood pressure than Blacks. There were no significant race or family history effects. Further, task performance did not influence the outcome. Failure to demonstrate greater cardiovascular reactivity in Blacks and all men with a positive family history of hypertension is discussed with regard to possible "survivor effects" and methodologic limitations.     

Facilitating empathy through virtual reality

This research experimentally investigated whether virtual reality experience can prompt greater empathy and whether greater engagement with a virtual reality connects this virtual reality experience to empathy. Randomly assigned participants viewed a documentary featuring a young girl living in a refugee camp either in a virtual reality format or in a control two-dimensional format. Results indicated that the virtual reality experience resulted in greater engagement and a higher level of empathy for the refugee girl compared to the control condition. Greater engagement was a process connecting the virtual reality experience to empathy. Virtual reality has the potential to influence interpersonal emotions such as empathy.     

The impact of cognitive behavioral therapy on post event processing among those with social anxiety disorder

Individuals with social anxiety are prone to engage in post event processing (PEP), a post mortem review of a social interaction that focuses on negative elements. The extent that PEP is impacted by cognitive behavioral therapy (CBT) and the relation between PEP and change during treatment has yet to be evaluated in a controlled study. The current study used multilevel modeling to determine if PEP decreased as a result of treatment and if PEP limits treatment response for two types of cognitive behavioral treatments, a group-based cognitive behavioral intervention and individually based virtual reality exposure. These hypotheses were evaluated using 91 participants diagnosed with social anxiety disorder. The findings suggested that PEP decreased as a result of treatment, and that social anxiety symptoms for individuals reporting greater levels of PEP improved at a slower rate than those with lower levels of PEP. Further research is needed to understand why PEP attenuates response to treatment.     

The effects of postural threat induced by a virtual environment on performance of a walking balance task

Rapid motor learning may occur in situations where individuals perceive a threat if they do not perform a task well. This rapid motor learning may be facilitated by improved motor performance and, consequently, more errorless practice. As a first step towards understanding the role of perceived threat on rapid motor learning, the purpose of this study was to determine how performance of a motor task is affected in situations where perceived threat is high. We hypothesized that perceived threat in a virtual environment would result in improved performance of a walking task (i.e., walking on a narrow beam). Results demonstrated that increased perceived threat did not yield statistically significantly greater balance performance in the high-threat virtual environment (median percentage of successful steps: 78.8%, 48.3%, and 55.2% in the real low-threat, virtual low-threat, and virtual high-threat environments, respectively). These results may be partially attributed to habituation to threat over time and practice. If implemented carefully, virtual reality technology can be an effective tool for investigating walking balance in environments that are perceived as threatening.     

Psychosocial stress evoked by a virtual audience: relation to neuroendocrine activity.

A modified version of the Trier Social Stress Test (TSST) was employed to determine whether exposure to a virtual audience using virtual reality (VR) technology would prompt an increase of neuroendocrine activity comparable to that prompted by a real audience. Following an anticipatory period, participants completed a speech or a speech-plus-math challenge in front of either a virtual audience, a panel of judges they were led to believe was behind a one-way mirror, or an audience comprised of confederates. An additional group that had prepared a speech was simply directed to observe the virtual audience but did not deliver the speech. Finally, a control group completed questionnaires for the duration of the experiment. Cortisol samples were obtained upon arrival to the laboratory, just before the challenge, and 15 and 30 minutes after the task. Participants also completed a measure assessing stressor appraisals of the task before and after the challenge. Anticipation of the task was associated with a modest increase of cortisol levels, and a further rise of cortisol was evident in response to the challenge. The neuroendocrine changes evoked by the virtual audience were comparable to those elicited by the imagined audience (behind the one-way mirror) but less than changes evoked by the panel of confederates. Stressor appraisals were higher post-challenge compared to those reported prior to the task; however, appraisals were similar across each group. These data suggest that VR technology may be amenable to evaluating the impact of psychosocial stressors such as the TSST.     

Hypertension risk and caffeine's effect on cardiovascular activity during mental stress in young men

Examined the cardiovascular effects of caffeine plus behavioral stress in men low versus high in risk of essential hypertension. Caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) or placebo was given on alternate days to 19 low-risk men (negative for parental hypertension and low-normal resting blood pressure, BP) and 20 high-risk men (positive history, high-normal BP). Forty minutes later, each worked for 15 min on a demanding psychomotor task during which BP, cardiac output, and vascular resistance were determined. During rest, caffeine raised vascular resistance in both groups. During the task, it supra-additively increased the systolic BP response by enhancing the rise in cardiac output, producing equivalent BP rises in both groups. Due to the higher resting pressures of the high-risk men, caffeine plus the task resulted in 50% of these having transient BP of 140/90 mg Hg or greater. Caffeine in combination with mental stress may produce undesirable BP in those at risk for hypertension.     

Body fat distribution and hemodynamic stress responses in premenopausal obese women: a preliminary study.

To examine the relationship between body fat distribution and hemodynamic stress responses, cardiovascular responses to a speech task and a forehead cold pressor task were evaluated with 24 premenopausal women classified a priori as either centrally or peripherally obese. Results showed that women with central adiposity exhibited greater stress-related increases in diastolic blood pressure and total peripheral resistance, whereas women with peripheral adiposity exhibited greater stress-related increases in cardiac output. Depression, self-consciousness, hostility, and mood scores did not explain significant variance in the stress response differences between regional adiposity groups. The findings suggest that central adiposity may increase the risk of cardiovascular disease in women at least in part by enhancing vascular responses to stress.     

Communality of videogame performances with tracking tasks

Performances on three videogames were compared with two different tracking tasks and a third dual tracking task, after stability of performance was achieved by 40 male subjects. The six tasks were performed in succession for three weeks each, and one year separated administration of the tracking tasks from the videogames. Convergence of the cross-correlations among these tasks occurred such that higher correlations were attained for scores obtained late in practice (late/late) of two tasks (even when they were performed a year apart) rather than for scores obtained earlier in training (viz., early/early). High communality between these two types of tasks was observed as indicated by virtual overlap between the videogames and the tracking tasks, even though different control media (joysticks, knobs), control orders (zero/first), and control inputs (displacement/force transducer) were required. Because these tasks apparently index similar abilities, there may be advantages to measuring tracking skills with videogames, which include low cost, wide availability, inherent interest to subjects and motivation, rapid approach to stable levels, and, in many cases greater apparent face validity relative to real world performance requirements.     

Cardiovascular and testosterone responses to contested dominance in women

Examined cardiovascular and testosterone responses of dominant and submissive women to an acute stressor involving contested dominance. Twenty (10 dominant, 10 submissive) university students rated their dominance to a predefined reference group, participated in a task that involved debating with a trained technician, and were continuously provided with bogus feedback throughout the task concerning biochemical substances in their blood that purportedly covaried with dominance. Covariance analyses revealed that dominant women were much more reactive to the stressor in several cardiovascular parameters than those classified as submissive. Serum testosterone did not vary as a function of the experimental manipulation, and at each measurement point, dominant and submissive subjects had essentially identical serum levels of this hormone. Interestingly, however, baseline testosterone for the dominant group was related to changes in systolic blood pressure (i.e., gain scores computed as task response minus baseline values).     

Patterns of cardiovascular responses to stress as a function of race and parental hypertension in men

This study investigated cardiovascular responses to two stressors known to elicit either beta-adrenergic (mental arithmetic) or alpha-adrenergic (forehead cold pressor) reactivity in Black and White men. Participants in each group were selected for presence or absence of parental hypertension. Based on previous research, Blacks were expected to show smaller cardiovascular responses to the beta-adrenergic mental arithmetic task and greater responses to the alpha-adrenergic cold pressor relative to the Whites. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate, forearm blood flow, and forearm vascular resistance were assessed during a resting baseline, a prestress period, and during and after each experimental procedure. Unlike previous findings, no significant racial differences in cardiovascular responses were found during either task. However, Black participants had significantly higher SBP and DBP levels throughout the cold pressor periods. Parental history did not significantly influence cardiovascular responses in either group. The results are discussed in relation to previous research on racial differences in stress reactivity and their implications for future research.     

Differential preparatory cardiovascular responses to aversive and appetitive behavioral conditioning

Dogs were required to press a response panel either to avoid shock or obtain food. During a one-hour interval immediatelypreceding performance on the avoidance task, blood pressure increased while heart rate decreased. In contrast, both blood pressure and heart rate increased during the one-hour interval immediatelypreceding performance on the food task. During both the shock-avoidance and food performancesper se, however, elevations in heart rate and blood pressure were observed, though the avoidance task produced less consistent heart rate changes. These effects were observed (1) with different individual dogs on each of the two training procedures, and (2) with the same dogs exposed successively to both aversive and appetitive behavioral conditioning.     

Effects of alcohol intoxication on risk taking, strategy, and error rate in visuomotor performance.

Adult men (N = 44) participated for 2 days (alcohol vs. placebo treatment) in a double-blind, crossover experiment. Performance on the Digit Symbol Substitution Task (DSST) and a visuomotor (VM) task was measured 4 times each day. On the alcohol-treatment day, data were obtained once during ascending breath alcohol levels (BALs), once during maximal BALs (0.05 or 0.10), and twice during descending BALs. Data were collected at the same time points on the placebo-treatment day. Limited evidence for acute tolerance was obtained with the DSST, but error rates on the VM task were higher during maximal and descending BALs. Error rates remained near placebo values, and participants displayed slightly greater caution, while BALs were ascending. Strategy scores on the VM task exceeded placebo scores during maximal intoxication. Data interpretation is focused on individuals in higher level (e.g., professional) positions.     

Individual differences in the impact of attentional bias training on cardiovascular responses to stress in women

Experimental studies show that training people to attend to negative stimuli makes them more likely to respond with greater anxiety to stress. The present study investigated this effect in students using measures of cardiovascular responses to stress and examined whether individual differences influence the impact of attention training on stress responses. Using a standard dot probe task, 30 participants underwent negative attentional bias training and 34 participants underwent anti-negative training before completing a stressful speech task. Results indicated that, overall, participants exhibited acclimatization to the procedures (indicated by a dip in blood pressure post-training) and normal stress responding (indicated by elevated blood pressure in response to stress; p<.001). However, consideration of participants' scores for neuroticism/emotional-stability revealed important differences in how the intervention impacted on cardiovascular profiles (p=.008). For participants with high neuroticism scores, the negative attentional bias intervention elicited more exaggerated stress responding than the anti-negative intervention. For those with low neuroticism scores (i.e., emotionally stable participants), the anti-negative intervention was associated with elevated post-intervention blood pressure and higher blood pressure reactivity to stress. These findings provide evidence of the impact of attentional bias manipulation on physiological stress reactivity and suggest the effect is highly contingent on individual temperaments.     

Attachment Anxiety, Verbal Immediacy, and Blood Pressure: Results from a Laboratory-Analogue Study Following Marital Separation

Marital separation and divorce increase risk for all-cause morbidity and mortality. Using a laboratory analogue paradigm, the present study examined attachment anxiety, language use, and blood pressure (BP) reactivity among 119 (n = 43 men, 76 women) recently separated adults who were asked to mentally reflect on their relationship history and separation experience. We created a language use composite of verbal immediacy from participants' stream-of-consciousness recordings about their separation experience as a behavioral index of attachment-related hyperactivation. Verbal immediacy moderated the association between attachment anxiety and BP at the beginning of a divorce-specific activation task. Participants reporting high attachment anxiety who discussed their separation in a first-person, present-oriented and highly engaged manner evidenced the highest levels of BP at the start of the divorce-specific task. Results provide a deeper understanding of the association between marital dissolution and health and suggest that verbal immediacy may be a useful behavioral index of hyperactivating coping strategies.     

Biopsychological bases and behavioral correlates of sensation seeking: contributions to a multilevel validation

Zuckerman presented a multilevel approach of sensation seeking comprising a hierarchy of seven levels. He primarily focussed on the levels of psychometric trait, psychophysiology and biochemistry. Because Zuckerman was less concerned with behavioral paradigms and experimental task performance the purpose of our study was to identify and validate behavioral paradigms whose behavioral components can be seen as valid indicators of the trait. But within the multilevel perspective, each paradigm should not only be structured and validated in relation to its psychometric dimension but also with regard to at least one other level and preferably through a within-design.Thirty-two undergraduates (18 female) and graduate students took part in the study. Subjects completed the Sensation Seeking Scale (Form V), the Impulsiveness Venturesomeness Empathy Questionnaire, and the Zuckerman Kuhlman Personality Questionnaire and performed three experimental paradigms: the continuous performance task, delayed reaction time task and the augmenting–reducing paradigm.The classical findings on augmenting–reducing were replicated (correlation between TAS and the N1/P2 slope). On this basis the expected positive correlation between sensation seeking and false alarms on the DRTT as a central parameter of experimental task performance was confirmed. This result is a first step to the validation of this task as a paradigm covering relevant aspects of sensation seeking. In addition, by means of communality analysis, it was shown that there is 8.6% of common variance across all three levels of measurement (psychometric, psychophysiological and experimental task performance). This overlapping variance can be regarded as a core region of a multilevel sensation seeking construct if the parameters for each of the levels of measurement involved are sufficiently validated.     

Increases in rewards promote flexible behavior

Offering reward for performance can motivate people to perform a task better, but better preparation for one task usually means decreased flexibility to perform different tasks. In six experiments in which reward varied between low and high levels, we found that reward can encourage people to prepare more flexibly for different tasks, but only as it increased from the level on the previous trial. When the same high rewards were offered continuously trial after trial, people were more inclined to simply stick with doing what had worked previously. We demonstrated such enhancements in flexibility in task switching, a difficult visual search task, and an easier priming of pop-out search task, which shows that this effect generalizes from executive tasks to perceptual processes that require relatively little executive control. These findings suggest that relative, transient changes in reward can exert more potent effects on behavioral flexibility than can the absolute amount of reward, whether it consists of money or points in a social competition.     

The relationship between blushing propensity, social anxiety and facial blood flow during embarrassment

To investigate blushing in relation to blushing propensity scores and core elements of social anxiety, facial blood flow was monitored in 86 normal volunteers during an embarrassing task (singing a children's song). Increases in facial blood flow were greater in women than men, as were scores on the Blushing Propensity and Fear of Negative Evaluation scales. In addition, high scores on the Blushing Propensity and Social Interaction Anxiety scales were associated with large increases in facial blood flow during singing. However, this appeared to be due primarily to social anxiety because the association between blushing propensity scores and changes in facial blood flow disappeared when social interaction anxiety scores were taken into account. These findings suggest that people generally base their beliefs about blushing on cues other than changes in facial blood flow. Social anxiety may augment increases in facial blood flow during embarrassment, independently of expected or perceived blushing.     

The relationship between blushing propensity,social anxiety and facial blood flow during embarrassment

To investigate blushing in relation to blushing propensity scores and core elements of social anxiety, facial blood flow was monitored in 86 normal volunteers during an embarrassing task (singing a children's song). Increases in facial blood flow were greater in women than men, as were scores on the Blushing Propensity and Fear of Negative Evaluation scales. In addition, high scores on the Blushing Propensity and Social Interaction Anxiety scales were associated with large increases in facial blood flow during singing. However, this appeared to be due primarily to social anxiety because the association between blushing propensity scores and changes in facial blood flow disappeared when social interaction anxiety scores were taken into account. These findings suggest that people generally base their beliefs about blushing on cues other than changes in facial blood flow. Social anxiety may augment increases in facial blood flow during embarrassment, independently of expected or perceived blushing.     

Reliability of psychophysiological assessment

In order to assess the reliability of psychophysiological recording, 15 subjects were assessed on multiple response measures (forehead EMG and forearm flexor EMG, heart rate, skin resistance level, hand surface temperature and cephalic vasomotor response), under multiple stimulus conditions (baseline, self-control, cognitive and physical Stressors), on multiple occasions (Days 1, 2, 8 and 28). Three forms of reliability coefficients were computed for each response measure: coefficients on absolute scores, coefficients on change scores from baseline to stressful conditions and coefficients on percent change from baseline. Only frontal EMG appeared to have consistently high absolute reliability coefficients, with hand surface temperature having high reliability if sessions are repeated within 1 week. Heart rate was less consistently reliable. Treating the responses as relative measures did not increase their reliability; indeed, hand surface temperature was completely unreliable when examined in this fashion. Implications of this study for behavioral medicine, biofeedback and anxiety-based disorders research, as well as Lang's tripartite response system model of fear and emotion, are discussed.