Effects of the presentation of false heart-rate feedback on the performance of two common heartbeat-detection tasks.

Research has indicated that performance on heartbeat counting tasks may be influenced by beliefs about heart rate. Sixty male subjects were administered the Schandry heartbeat counting task after viewing fast, slow, or no heart rate feedback. Subjects were also administered the Whitehead signal-detection type task. Results indicated that subjects who received fast or no heartbeat feedback performed better on the Schandry task than subjects who received slow feedback. Feedback presentation did not affect performance on the Whitehead task. These results suggest that the Schandry task is influenced by external variables (expectations, beliefs) beyond pure awareness of "discrete" visceral sensations and, thus, may not be as powerful a method for determining awareness of individual heartbeats as some other paradigms.     

A Comparison between Two Methods for Assessing Heartbeat Perception

In this study two methods assessing heartbeat perception ability were compared. Subjects (N = 64) completed Schandry's (1981) mental tracking task and Störmer's (1988) heartbeat discrimination procedure (based on Whitehead, Drescher, Heiman, & Blackwell, 1977). In addition, subjects were tested on their ability to estimate the duration of time intervals. A high degree of correspondence was found between the two heartbeat perception tasks for the extreme groups of very good and very poor perceivers, but a low degree of correspondence emerged for the middle range of performance (overall r= .59, p<.001). Time estimation did not correlate significantly with either heartbeat detection procedure. Blood pressure measurements taken after the Schandry task and between Störmer test blocks showed that blood pressure amplitude was elevated among good perceivers on both heartbeat detection tasks.     

Hemodynamics of Blood Pressure Responses During Active and Passive Coping

This laboratory study was designed to address a number of interrelated issues regarding cardiovascular reactivity to psychological stress. One objective was to extend the previous research comparing cardiovascular responses during active versus passive coping, by comparing responses to two task conditions designed to be similar in all ways except the opportunity to make a response influencing the task's outcome. A second objective was to compare responses to two different passive film tasks, which differed in outcome uncertainty and the degree of vicarious active coping achieved through identification with the role portrayed by the actors. A third objective was to evaluate whether individuals are predisposed to exhibit a particular hemodynamic pattern underlying their blood pressure adjustments, independently of the task demands imposed. Ninety healthy young adult male subjects were tested in pairs on a series of tasks that included a competitive reaction-time task, an active as well as a passive phase of a team reaction-time task, and passive viewing of two film segments. The tasks demanding active coping responses tended to raise blood pressure due primarily to an increase in cardiac output, while vascular resistance fell. During passive coping demands cardiac output increased to a lesser extent, but vascular resistance also tended to increase, thereby raising blood pressure by their synergistic effects. However, these patterns were not typical of all participating subjects. On the basis of their cardiac output and vascular resistance responses to the competitive reaction-time task, one third of the subjects were categorized as being high myocardial reactors (n = 30) and another third high vascular reactors (n = 31). Post-hoc analyses of responses to the other tasks, based on these categorizations, indicated that the hemodynamic basis of reactivity is an individual characteristic only partially modified by coping demands. The active/passive coping dimension is discussed both conceptually and in relation to the role of stress in the etiology of hypertension.     

Serum Lipids,Neuroendocrine, and Cardiovascular Responses to Stress in Men and Women with Mild Hypertension

Abstract

In this study, we examined the relation between serum lipid levels, gender, and cardiovascular and neuroendocrine stress reactivity in patients with mild hypertension. Ninety-nine individuals (62 men, 37 women) with mild hypertension performed four mental stress tasks: mental arithmetic, public speaking, cold stress, and a computer videogame. Cardiovascular reactivity scores were computed by subtracting the minimum resting blood pressure (BP) and heart rate (HR) values from the maximum values obtained during each task. Neuroendocrine reactivity was calculated as the change from epinephrine and norepinephrine values from mean rest to mean task. High and low reactors were identified on the basis of median splits of reactivity scores, averaged across all four stressors. High systolic blood pressure reactors had higher levels of total (TC), low-density lipoprotein cholesterol (LDL-C), and apo-B than did low reactors. High diastolic blood pressure reactors had lower levels of high-density lipoprotein cholesterol (HDL-C) and higher levels of LDL-C and apo-B than did low reactors. High HR reactors had higher apo-AI:apo-AII ratios than low reactors. Lipid levels were not different for high and low epinephrine and norepinephrine reactors. Although women were noted to have more favorable lipid profiles than men, both male and female hypertensive patients who were high reactors had less favorable lipid profiles than low reactors.     

The effect of monocular viewing on heartbeat discrimination

In monocular viewing conditions, an activational imbalance between the cerebral hemispheres was assumed to develop, the direction of which depends on the side of the viewing eye. This assumption was based on the morphological differences between the nasal and the temporal hemiretinas and on physiological data. It was assumed that the hemisphere receiving visual information via the nasal optic fibers, that is, the hemisphere contralateral to the viewing eye, would be the more activated one. Because heartbeat perception is regarded as a predominantly right hemispheric function, it was predicted that during right hemispheric activation created by left monocular viewing heartbeat discrimination performance would be better than during left hemispheric activation created by right monocular viewing. This hypothesis was tested on 30 male right-handed university students who performed a Whitehead-type heartbeat discrimination task while viewing only with the left or with the right eye. Heartbeat perception was more accurate when viewing with the left eye. Additionally, respiratory manipulation during heartbeat discrimination improved performance on this task.     

Follow your breath: Respiratory interoceptive accuracy in experienced meditators

Attention to internal bodily sensations is a core feature of mindfulness meditation. Previous studies have not detected differences in interoceptive accuracy between meditators and nonmeditators on heartbeat detection and perception tasks. We compared differences in respiratory interoceptive accuracy between meditators and nonmeditators in the ability to detect and discriminate respiratory resistive loads and sustain accurate perception of respiratory tidal volume during nondistracted and distracted conditions. Groups did not differ in overall performance on the detection and discrimination tasks; however, meditators were more accurate in discriminating the resistive load with the lowest ceiling effect. Meditators were also more accurate during the nondistracted tracking task at a lag time of 1 s following the breath. Results provide initial support for the notion that meditators have greater respiratory interoceptive accuracy compared to nonmeditators.     

The Effect of Lateral Visual Fixation and the Direction of Eye Movements on Heartbeat Discrimination

This study was undertaken to determine whether the asymmetrical activation of the two cerebral hemispheres affects the accuracy of heartbeat perception. Hemispheric preference--the tendency to activate one hemisphere rather than the other--was assessed by the directionality of conjugate lateral eye movements. Actual differential hemispheric activation was achieved by contralateral visual fixation. The results of 44 right-handed male subjects showed that right hemisphere preferent subjects ("left-movers") performed better on a heartbeat discrimination task than left hemisphere preferent subjects ("right-movers"). The direction of lateral visual fixation also influenced heartbeat discrimination: subjects fixating to the left were more accurate than those fixating to the right.     

Does cardiovascular reactivity to stress measured in the laboratory generalize to thesis and dissertation meetings among doctoral students?

This study extends previous work investigating the generalizability of cardiovascular reactivity to stress obtained in response to laboratory-based tasks to cardiovascular reactivity measured in response to a naturally occurring event. Heart rate (HR) and blood pressure reactivity to stress were measured with ambulatory monitoring equipment in 6 male and 16 female healthy, White, graduate students in two settings: during five standardized stressors in the laboratory, and during the proposal or defense of a thesis or dissertation. Results indicate that for all cardiovascular parameters, the magnitude of change was greatest in response to the natural event, and that among the laboratory tasks, the greatest degree of reactivity was observed in response to a speech task. However, the cardiovascular reactivity associated with the speech task was not the best predictor of the natural speech task, despite the structural similarity of these two tasks. Overall, greater correlations were noted among all of the tasks based on absolute values of HR and blood pressure versus residualized change scores for HR and blood pressure, and greater correlations also were observed among anticipation periods than among task periods. Partial support was provided for the hypothesis that the generalizability of cardiovascular reactivity to stress would be enhanced by using multiple laboratory tasks rather than single tasks. This effect was observed for HR but not blood pressure. Consistent with the literature in this field, we observed only limited generalizability of cardiovascular response to stress from laboratory to the field. This project was supported through the grant-in-aid program of the American Heart Association’s West Virginia Affiliate (Grant 93–7854S). Portions of this article were presented at the 30th Annual Meeting of the Association for the Advancement of Behavior Therapy in November 1996 and at the 20th Annual Meeting of the Society for Behavioral Medicine in March 1999.     

Signal-detection outcomes on heartbeat and respiratory resistance detection tasks in male and female subjects

Male and female subjects were compared on heartbeat, respiratory resistance, and light-tone signal-detection tasks. Subjects judged whether a series of 10 tones was coincident with their heartbeats; whether an external load added to the airway was either present or absent during targeted inspiratory cycles; and whether a series of 10 light flashes was matched with auditory tones presented following a fixed delay of either 50 or 100 ms. Nonparametric indices of perceptual sensitivity and response bias indicated that men were more sensitive than women on the resistive load task (p < .05) and on the heartbeat task (p= .07). Performance on the light-tone task was virtually identical. All subjects used a stricter criterion on the respiratory resistance task than on either the heartbeat or the light-tone task; women employed a stricter criterion than men on the heartbeat task. The gender differences may be understood in terms of lateralization of central processing of somesthetic sensory information.     

EFFECTS OF A TASK-RELEVANT RESPONSE ON PUPIL SIZE

This experiment examined the effects on pupil size of the relevance of an overt response to a cognitive task. Sixteen Ss were assigned to two experimental groups. In one group Ss were required to judge the pitch equality of tones and, subsequently, indicate their decision by pressing or not pressing a telegraph key. In the other group Ss were required to make the pitch-discriminations, but the key press response was unrelated to the preceding cognitive task. Continuous photographs of each S's pupil were taken during the experiment. Results showed that a small amount of pupillary dilation occurred during the discrimination task in the group where the key press was irrelevant to the pitch-discrimination. In the group where S's behavior indicated task fulfillment, however, a significantly greater increase in pupil size occurred, the amount of dilation being larger when task completion was indicated by the key press response than when fulfillment was indicated by no key press. The findings were discussed in terms of arousal associated with apprehension about evaluation, and muscle tension from anticipation of making the overt response.     

Heart Rate Discrimination Viewed as a Perceptual Process: A Replication and Extension

Two experiments are reported which investigate the efficacy of Ashton, White, and Hodgson's (1979) two-alterative-forced-choice discrimination technique for training accuracy in perception of heart rate. In the first study, subjects were assigned to either a knowledge of results (KR) or no-knowledge of results condition (noKR). In the second study a third condition, augmented feedback (AFB), was added. The two studies differed essentially in the timing of the commencement of training, and in the number of training sessions employed. Transfer of training was assessed in both studies by testing all subjects on a heartbeat discrimination task modified from Brener and Jones (1974). The pattern of results was consistent in indicating that providing subjects with information about the accuracy of their decisions is an effective means of training cardiac awareness, and that transfer of the trained awareness to a more commonly used exteroceptive discrimination procedure occurs. The data also point to the possibility that allowing subjects to “practice” prior to any training may be a procedural measure best avoided in discrimination training experiments.     

Heart rate discrimination and heart rate control: a test of Brener's theory

Three experiments were conducted to examine predictions from Brener's theory regarding the relationship between autonomic discrimination and autonomic control. Experiment 1 examined the possibility that training subjects to discriminate their heart rates would enhance their skill at controlling that response. Twenty subjects participated in two sessions during which one group of 10 subjects received training (knowledge of results) on the Ashton discrimination technique. The second group performed the discrimination task but received no training. All subjects then took part in a third session of heart rate (HR) control (both increase and decrease) where half of each of the aforementioned groups received feedback during the control task, while the other half performed the HR control task without feedback. Results indicated that for the control of both HR increases and decreases, there was no significant difference between those subjects trained to discriminate their HR, and those who had received no training to discriminate HR. The second experiment investigated the hypothesis that training subjects with feedback to control their HR would enhance their capacity to discriminate their heart activity. Ten subjects participated in two sessions of HR control during which half the subjects received feedback training to increase HR. During a third session, all subjects underwent a test of discrimination ability using the Ashton technique, and no knowledge of results regarding performance was provided. Results confirmed the hypothesis. The final experiment in the series investigated the discrimination/control relationship within a problem-solving framework and used 20 subjects. Results confirmed the hypothesis that subjects forewarned at the time of discrimination training that a heart rate control task was to follow would perform better than 10 subjects receiving no forewarning of the task objective. This effect took place independently of cardiac discrimination ability. A second finding from this experiment was that subjects trained to discriminate heart rate were better able to increase heart rate than untrained subjects. This result contradicts that of Experiment 1, and reasons for this anomaly are discussed in detail.     

Olfactory dysfunction in alzheimer's disease

Recent evidence suggesting involvement of the central olfactory system in Alzheimer's disease (AD) was assessed by contrasting olfactory and visual discrimination in 15 probable AD subjects and 6 healthy aged controls. Control subjects performed better than AD subjects on both tasks. Mild AD subjects performed better than moderate AD subjects on visual discrimination, although the two groups did not differ on olfactory discrimination. Positron emission tomographic (PET) studies with (F‐18)2‐fluoro‐2‐deoxy‐D‐glucose performed on 11 of the AD subjects showed no relation between olfactory performance and cerebral metabolic asymmetries, but relations to visual discrimination were found.     

Cardiovascular Responses to Effortful Active Coping: Implications for the Role of Stress in Hypertension Development

Recent contributions to the literature on stress and hypertension are discussed. The significance of effortful active coping in evoking sympathetically-mediated heart rate and blood pressure increases is supported by results of studies involving both aversive and appetitive task incentives. Young healthy males who are above-average in heart rate during coping tasks show consistently higher heart rates and systolic pressures during other stresses as well, but are indistinguishable from less reactive persons when relaxed. Studies involving beta-blockade indicate that these above-average cardiovascular increases are partly due to a greater beta-adrenergic response among the high heart rate reactors. In addition, the parents of these high heart rate reactors report a greater incidence of hypertension than parents of low reactors, suggesting that high cardiovascular responses during active coping stress may reflect a high degree of susceptibility to later hypertension.     

Coronary-Prone Behavior Pattern, Task Incentive, and Cardiovascular Response

In this experiment it was predicted that the presence or absence of a performance-contingent incentive (monetary reward) would mediate effects of the coronary-prone behavior pattern on behavioral and cardiovascular responses to a difficult cognitive task. Accordingly, 44 subjects of the Type A (coronary-prone) and Type B (non-coronary-prone) behavior patterns were assigned to one of two task conditions, labelled Incentive and No Incentive. Results indicated that under No Incentive Type As performed better at the experimental task and reported less state anxiety than Type Bs, whereas in the Incentive condition, Type A and B subjects showed no differences in task performance or self-report of anxiety. Concerning cardiovascular measures, analysis of variance revealed significantly greater systolic blood pressure and pulse pressure elevations for Type A than Type B subjects, but showed no reliable interactions of the Type A, B and Incentive factors nor any related effects regarding heart rate or diastolic blood pressure. Individual differences in subjects' scores on the inventory for coronary-prone behavior pattern, however, correlated positively with heart rate accelerations in the No Incentive condition, but did not covary with heart rate changes under Incentive. With respect to subjects' perceptions of the task, self-report data suggested that Type As responded in a more active and involved manner and resisted feelings of helplessness to a greater extent than their Type B counterparts.     

Music can facilitate blood pressure recovery from stress

Objectives: Interventions that reduce the magnitude of cardiovascular responses to stress are justified, at least in part, by the notion that exaggerated responses to stress can damage the cardiovascular system. Recent data suggest that it is worthwhile to explore, in addition to the magnitude of the cardiovascular responses during stress (reactivity), the factors that affect the return to baseline levels after the stressor has ended (recovery). This experiment examined the effect of listening to music on cardiovascular recovery. Design and method: Participants (N = 75) performed a challenging three‐minute mental arithmetic task and then were assigned randomly to sit in silence or to listen to one of several styles of music: classical, jazz or pop. Results: Participants who listened to classical music had significantly lower post‐task systolic blood pressure levels (M = 2.1 mmHg above pre‐stress baseline) than did participants who heard no music (M = 10.8 mmHg). Other musical styles did not produce significantly better recovery than silence. Conclusions: The data suggest that listening to music may serve to improve cardiovascular recovery from stress, although not all music selections are effective.     

Dissociating beliefs about heart rates and actual heart rates in patients with cardiac pacemakers.

Performance on heartbeat counting tasks is usually interpreted in terms of cardiac sensitivity. We tested the hypothesis that heartbeat counting is influenced by beliefs about heart rates by dissociating beliefs about heart rates and actual heart rates. In a within-subjects design, heart rates of 50 patients with cardiac pacemakers were set to a low (50 bpm), medium (75 bpm), or high (110 bpm) pacing rate unknown to the patients via remote control while they performed a heartbeat tracking task. Results showed that patients' heartbeat counting did not follow the shifts in their actual heart rates adequately, although their overall performance was comparable to that of young and healthy control participants. As a result, tracking scores decreased significantly in the high pacing rate condition where beliefs about heart rates and actual heart rates were most extremely dissociated. The findings suggest that tracking scores reflect beliefs about heart rates rather than cardiac sensitivity.     

Task-related modulation of visual cortex

We performed a series of experiments to quantify the effects of task performance on cortical activity in early visual areas. Functional magnetic resonance imaging (fMRI) was used to measure cortical activity in several cortical visual areas including primary visual cortex (V1) and the MT complex (MT+) as subjects performed a variety of threshold-level visual psychophysical tasks. Performing speed, direction, and contrast discrimination tasks produced strong modulations of cortical activity. For example, one experiment tested for selective modulations of MT+ activity as subjects alternated between performing contrast and speed discrimination tasks. MT+ responses modulated in phase with the periods of time during which subjects performed the speed discrimination task; that is, MT+ activity was higher during speed discrimination than during contrast discrimination. Task-related modulations were consistent across repeated measurements in each subject; however, significant individual differences were observed between subjects. Together, the results suggest 1) that specific changes in the cognitive/behavioral state of a subject can exert selective and reliable modulations of cortical activity in early visual cortex, even in V1; 2) that there are significant individual differences in these modulations; and 3) that visual areas and pathways that are highly sensitive to small changes in a given stimulus feature (such as contrast or speed) are selectively modulated during discrimination judgments on that feature. Increasing the gain of the relevant neuronal signals in this way may improve their signal-to-noise to help optimize task performance.     

Family history of hypertension,gender, and cardiovascular reactivity and stereotypy during stress

Thirty subjects with a family history of hypertension and 28 subjects without such a history performed a Stroop Color-Word Interference task, a mental arithmetic task (serial subtraction of sevens), and a shock avoidance task (repeating digits backward while expecting to be shocked for mistakes). Systolic and diastolic blood pressure and pulse rate were recorded while subjects anticipated, undertook, and recovered from the shock avoidance task and undertook and recovered from the Stroop and mental arithmetic tasks. It was found that compared to nonfamily history subjects, family history subjects manifested reliably greater cardiovascular reactivity during each task and in anticipation of the shock avoidance task. These results are congruent with the notion that excessive sympathetic nervous system reactivity—possibly genetically determined—is involved in the development of some form(s) of essential hypertension. Further, the results indicated that family history subjects manifested greater consistency, or stereotypy, of cardiovascular response across the experimental tasks than nonfamily history subjects. The possible role of cardiovascular stereotypy in the development of essential hypertension is also discussed.This investigation was supported by University of Kansas General Research Allocation 3115-xO-0038 to B. Kent Houston.     

Manipulating cardiovascular indices of challenge and threat using resource appraisals

Challenge and threat reflect two distinct psychophysiological approaches to motivated performance situations. Challenge is related to superior performance in a range of tasks compared to threat, thus methods to promote challenge are valuable. In this paper we manipulate challenge and threat cardiovascular reactivity using only resource appraisals, without altering perceived task demands between challenge and threat conditions. Study 1 used a competitive throwing task and Study 2 used a physically demanding climbing task. In both studies challenge task instructions led to challenge cardiovascular reactivity and threat task instructions led to threat cardiovascular reactivity. In Study 1, participants who received challenge instructions performed better than participants who received threat instructions. In Study 2, attendance at the climbing task did not differ across groups. The findings have implications for stress management in terms of focusing on manipulating appraisals of upcoming tasks by promoting self-efficacy and perceived control and focusing on approach goals. Future research could more reliably assess the influence of similar task instructions on performance.