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Biomedical subjects

J T Cacioppo

Publications and source records attributed to J T Cacioppo.

At least 19 recordsLinked to original sources
PubMed1995

Bioelectrical echoes from evaluative categorization: II. A late positive brain potential that varies as a function of attitude registration rather than attitude report.

We report evidence of both correspondence and independence between participants' attitude report and a late positive potential (LPP) of the event-related potential. Attitude reports and LPPs to positive, neutral, and negative stimuli that were preceded by positive stimuli were recorded while participants either reported accurately their attitudes or misreported neutral or negative attitudes. Evaluatively inconsistent, in contrast to consistent, stimuli evoked a larger LPP regardless of whether participants reported accurately or misreported their attitudes. These results were replicated in a second study in which attitude reports and LPPs to negative, neutral, and positive stimuli that were preceded by negative stimuli were recorded. Findings suggest that the LPP evoked during evaluative judgments reflects attitude categorization rather than attitude report processes and can potentially assess attitudes that people are unwilling to report.

Adult↗
PubMed1995

Individual differences in cardiac sympathetic control predict endocrine and immune responses to acute psychological stress.

Potential mechanisms coordinating individual differences in cardiovascular reactivity and endocrine and immune responses to acute psychological stress were examined. Twenty-three young, healthy women performed a mental arithmetic challenge while measures of cardiovascular, endocrine, and immune function were assessed. Results revealed that the acute stressor was associated with changes in the cardiovascular, endocrine, and immune systems. More important analyses revealed that individual differences in cardiovascular reactivity predicted stress-induced cortisol changes. Furthermore, cardiac sympathetic control, as indexed by preejection period, was specifically related to changes in natural killer cell activity. These results suggest that distinct physiological pathways are activated in response to acute psychological stress.

Adolescent↗
PubMed1995

The metrics of cardiac chronotropism: biometric perspectives.

The selection of heart period versus heart rate as a chronotropic metric has been considered from quantitative and statistical perspectives, which have not yielded a universal preference for either metric. In the present paper, we discuss biometric considerations that bear on the selection of the optimal chronotropic metric. Biometric evidence reveals that the transfer functions relating autonomic nerve traffic to chronotropic effects on the heart are more nearly linear for heart period than for heart rate. This confers considerable advantage on heart period as a chronotropic metric and can facilitate the study of psychophysiological relationships. We further show that heart period offers greater flexibility, because heart period data can be evaluated in cardiac time units (beats) or in real-time units (s), whereas heart rate data can only be analyzed in real time. These considerations suggest clear advantages to heart period as a chronotropic metric.

Animals↗
PubMed1995

Delay in seeking a cancer diagnosis: delay stages and psychophysiological comparison processes.

Two analyses of patient delay in seeking a medical diagnosis are considered. In the first, a model of delay is presented. Specifically, delay is comprised of four stages (appraisal, illness, behavioural and scheduling delay intervals), each governed by a conceptually distinct set of decisional and appraisal processes beginning with the initial day that an unexplained symptom is detected to the day the individual appears before a physician. The second analysis is a social psychological one of the attributions individuals draw when relating their symptoms to their expectations and knowledge about physiological bodily processes. The eight principles of Psychophysiological Comparison Theory (PCT) provide the basis for clarifying the psychological processes of symptom interpretation and appraisal. Two studies were conducted with women seeking diagnostic evaluations for prevalent cancers: breast or gynaecological tumours. Regarding the delay model, results indicated that the delay intervals were independent (i.e. uncorrelated). Also, appraisal delay constituted the majority (at least 60 per cent) of the total delay. In the test of PCT, support was found across measures of symptoms, the context in which the symptoms arose, and the inferences people made about the symptoms.

Adolescent↗
PubMed1995

The dissociation of catecholamine and hypothalamic-pituitary-adrenal responses to daily stressors using dexamethasone.

The hypothalamic-pituitary-adrenal (HPA) and sympathetic-adrenal-medullary (SAM) systems are implicated in the human stress response. One characterization of these systems is that they are nonspecific in their response, but differ in activation threshold and time course. Additionally, they have been found to be affected commonly by strong metabolic stressors and infusions of CRH, and a hypothesis has been developed primarily from animal research that CRH stimulates both the HPA and SAM systems. To determine whether CRH was significantly involved in tonic as well as psychological stress-induced catecholamine levels in man, we infused 24 normal male undergraduate students with either saline (n = 12) or dexamethasone (DEX; n = 12) and evaluated their subsequent plasma levels of ACTH, cortisol, epinephrine (EPI), and not epinephrine (NEPI). DEX produced a dramatic decrease in ACTH and cortisol levels, but no significant changes in EPI or NEPI occurred over a 4-h sampling interval. After the administration of math and speech stressors in a controlled laboratory setting, DEX inhibited the ACTH and cortisol release that was noted in the saline group, but stress-induced increases in EPI and NEPI were comparable in both groups. Thus, our study suggests that there is a difference in the neural pathways for tonic and stress-induced stimulation of the SAM and HPA systems.

Adrenocorticotropic Hormone↗
PubMed1994

Autonomic cardiac control. I. Estimation and validation from pharmacological blockades.

Pharmacological blockades have been used to estimate the relative contributions of the autonomic branches to cardiac chronotropic control. Systematic biases in these estimates, however, can arise from both methodological and physiological factors. Selective blockades can be interpreted by two inferential models, and a single blockade condition can yield estimates of autonomic control for both autonomic branches. The residual autonomic control of the heart after blockade of a single division provides an index of the functional contribution of the unblocked branch. In contrast, the change in chronotropic state of the heart after blockade of the same division reflects the subtractive loss of that branch and thus provides an index of the normal contribution of the blocked branch. We demonstrate that the systematic biases that can arise in blockade studies introduce distortions of the subtractive and residual estimates that are of equal magnitude but opposite sign. Consequently, the discrepancy between the subtractive- and residual-model estimates provides a measure of bias in blockade studies and permits the derivation of validity indices that can facilitate interpretations of blockade data.

Adrenergic Antagonists↗
PubMed1994

Autonomic cardiac control. II. Noninvasive indices and basal response as revealed by autonomic blockades.

Heart period, systolic time intervals, low and high frequency heart period variability, blood pressure, and respiration were measured in female subjects under three drug conditions (saline, atropine sulfate, metoprolol) while sitting and standing on three consecutive days. Following preinfusion baseline recordings, saline, metoprolol (14 mg), or atropine sulfate (2 mg) was infused for 15 min (by using a double-blind procedure). Recordings were taken during a postinfusion baseline and in response to an orthostatic stressor (standing versus sitting postures). At the end of the metoprolol session, atropine sulfate was infused and responses were monitored during the postinfusion (i.e., double blockade) baseline and during orthostatic stressor. Analyses of the blockade data revealed that the preejection period (PEP) reflected sympathetic but not vagal influences on the heart, and high frequency (HF, 0.12-0.40 Hz) heart rate variability (respiratory sinus arrhythmia) reflected vagal but not sympathetic influences on the heart. No other measure provided a specific index of the tonic sympathetic or vagal activation of the heart. Postinfusion PEP under saline predicted individual differences in postinfusion cardiac sympathetic activation, whereas postinfusion heart period (but not HF variability) under saline predicted individual differences in postinfusion cardiac vagal activation.

Adult↗
PubMed1994

Autonomic cardiac control. III. Psychological stress and cardiac response in autonomic space as revealed by pharmacological blockades.

Behavioral contexts can evoke a variety of autonomic modes of response, characterized by reciprocal, coactive, or independent changes in the autonomic divisions. In the present study, we investigated the reactive autonomic control of the heart in response to psychological stressors, using quantitative methods for analyzing single and double autonomic blockades, and through the use of noninvasive indices based on heart period variability and systolic time intervals. Analysis of the effects of pharmacological blockades revealed an overall pattern of increased sympathetic and decreased parasympathetic control of the heart during speech stress, mental arithmetic, and a reaction-time task. Unlike the classical reciprocal sympathetic-parasympathetic response to orthostatic challenge, however, the responses of the autonomic branches to stress were uncorrelated. This reflected notable individual differences in the mode of autonomic response to stress, which had considerable stability across stress tasks. The putative noninvasive indices of sympathetic (preejection period) and parasympathetic (respiratory sinus arrhythmia) control changed in accord with the results of pharmacological blockades. Together, these results emphasize the substantial individual differences in the mode of autonomic response to stress, the advantages of a quantitative approach to analyzing blockade data, and the importance of validity estimates of blockade data.

Adult↗
PubMed1992

Vagal stimulation and cardiac chronotropy in rats.

Increasing frequencies of electrical stimulation of the right vagus nerve in the rat yielded a progressive lengthening of heart periods. Stimulation was capable of driving vagal control of cardiac chronotropy over its full physiological dynamic range, to the point of sinus block. The steady-state transfer function between vagal stimulation frequency and cardiac chronotropy was approximately linear, with a slope of 7.4 ms/Hz. The linearity of the stimulation-heart period function is consistent with previous reports in dogs, rabbits and humans, although the slope of the function was considerably lower in the rat.

Animals↗
PubMed1992

Social psychological contributions to the decade of the brain. Doctrine of multilevel analysis.

The 1990s were declared by Congress to be the "decade of the brain." This declaration is important to all psychologists, not only neuroscientists, because with this declaration come expectations of the cognitive and behavioral sciences generally and because the brain does not exist in isolation but rather is a fundamental component of developing and aging individuals who themselves are mere actors in the larger theater of life. This article examines the importance of a multilevel, integrative approach to the study of mental and behavioral phenomena in the decade of the brain, reviews how this approach highlights the synergistic relationship between theoretical and clinically relevant research, and illustrates how this approach can foster the transition from microtheories to general psychological theories.

Behavior↗
PubMed1992

Relationship between facial expressiveness and sympathetic activation in emotion: a critical review, with emphasis on modeling underlying mechanisms and individual differences.

Two important questions bearing on personality processes and individual differences are how do facial expressiveness and sympathetic activation vary as a function of the intensity of an emotional stimulus, and what is the functional mechanism underlying facial expressiveness and sympathetic activation in emotion? A formulation is proposed that is based on 2 propositions: (a) All strong emotions result in some degree of activation of the organism (i.e., principle of stimulus dynamism) and (b) there are individual differences in the gain (amplification) operating on the facial expressive and sympathetic response channels (i.e., principle of individual response uniqueness). This formulation organizes much of the existing data on internalizers and externalizers and yields novel predictions regarding the subpopulation labeled as generalizers.

Arousal↗
PubMed1992

Age-related changes in cardiovascular response as a function of a chronic stressor and social support.

The effects of aging, chronic stress, and social support on cardiovascular functioning were examined using a cross-sectional design. Thirty-six family caregivers of Alzheimer's disease victims and 34 control Ss performed 2 active coping tasks while continuous noninvasive measures of cardiovascular activity were monitored. Results revealed that caregivers high in social support displayed typical age-related decreases in heart-rate reactivity, whereas caregivers low in social support displayed age-related increases in heart-rate reactivity. Analyses further indicated that only Ss with low social support were characterized by age-related increases in systolic blood pressure. These results suggest that social support can moderate age-related changes in cardiovascular functioning, particularly in Ss exposed to a chronic stressor.

Adult↗
PubMed1991

Autonomic determinism: the modes of autonomic control, the doctrine of autonomic space, and the laws of autonomic constraint.

Contemporary findings reveal that the multiple modes of autonomic control do not lie along a single continuum extending from parasympathetic to sympathetic dominance but rather distribute within a 2-dimensional space. The physiological origins and empirical documentation for the multiple modes of autonomic control are considered. Then a formal 2-dimensional conception of autonomic space is proposed, and a quantitative model for its translation into a functional output surface is derived. It is shown that this model (a) accounts for much of the error variance that has traditionally plagued psychophysiological studies, (b) subsumes psychophysiological principles such as the law of initial values, (c) gives rise to formal laws of autonomic constraint, and (d) has fundamental implications for the direction and interpretation of a wide array of psychophysiological studies.

Animals↗
PubMed1990

Inferring psychological significance from physiological signals.

A century has passed since the publication of William James's Principles of Psychology, yet most of the questions James raised about the relation between physiological events and molar psychological or behavioral processes, such as emotion, remain unanswered. The sluggish progress in capitalizing on physiological signals to address general psychological questions is due in part to shortcomings in the quantification of physiological signals in humans and, perhaps more important, to the way in which investigators have been thinking about the relation between physiological signals and psychological operations. In this article, we illustrate these points, and we provide a conceptual framework to foster research and analysis of psychological phenomena based on physiological signals. Psychological operations and physiological responses are defined in terms of configural and temporal properties, and psychophysiological relations are conceptualized in terms of their specificity (e.g., one-to-one versus many-to-one) and their generality (e.g., situation or person specific versus cross-situational and pancultural). This model yields four classes of psychophysiological relations: (a) outcomes, (b) concomitants, (c) markers, and (d) invariants. Finally, the model specifies how to determine whether a psychophysiological relation is an outcome, concomitant, marker, or invariant, and it describes important limitations in inferences of psychological significance based on physiological signals when dealing with each.

Behavior↗
PubMed1990

Rudimentary physiological effects of mere observation.

Complex social factors can influence physiological activity, behavior, and health, but little is known about how essential components of these factors (e.g., human association, observation) affect human physiology. To begin to address this issue, an experiment was conducted to contrast predictions from social facilitation, distraction/conflict, and physiological reactivity formulations regarding the physiological effects of mere observation. Skin conductance and heart rate were measured surreptitiously from 27 women during a period in which they believe that the experimenter was simply calibrating auditory and physiological recording equipment. Approximately half of the subjects were led to believe that they could be observed by the experimenter during this period, and the remainder were led to believe that they could not be observed. Following baseline recordings, a series of 10 orienting tones were presented. Predictions from the physiological reactivity formulation were supported: (a) no differences in basal levels of somatovisceral activity were found as a function of mere observation; (b) mere observation enhanced the skin conductance response to the initial orienting tone; and (c) these physiological differences were punctate, quickly dissipating and quickly habituating. Hence, mere observation has subtler physiological effects than thought previously. Implications are discussed regarding the possible mechanism underlying the stress-enhancing and stress-buffering effects of human association, and regarding the effects social and contextual factors may have in psychophysiological research. Results from an international survey, based on the responses of 57 authors of articles that have appeared in Psychophysiology since 1983, are reported to inform the latter discussion. Results suggest that, even when social factors in psychophysiological research are minimized or held constant within studies, subtle differences in the social context across studies within and across laboratories may contribute to the appearance that psychophysiological relationships are unreliable.

Adolescent↗
PubMed1990

Issues in biometrics: offset potentials and the electrical stability of Ag/AgCl electrodes.

There has been a continuing interest in many areas of psychophysiological research in the quantification of slow wave bioelectric potentials recorded from the surface of the skin. However, surprisingly little research has focused specifically on methods for stabilizing and minimizing the offset potentials of the sintermetallic Ag/AgCl surface electrodes commonly used in such noninvasive bioelectric measurement. To provide empirically based recommendations in this regard, we contrasted the effects of three common storage methods (air dry vs. saline vs. carbon rod) on the two distinct types of Ag/AgCl surface electrodes (sintermetallic vs. electrolytic) under simulated experimental conditions. The obtained results confirm that minimum offset potentials and maximum stability for electrolytic Ag/AgCl electrodes are obtained when they are stored in a 0.9% NaCl solution with their leads shorted together and connected in parallel to a carbon rod partially immersed in the solution (cf. Cooper, 1956). In addition, the pattern of results suggested that the inter-session unshorted storage of sintermetallic electrodes in a mild saline solution is to be recommended over either shorted saline storage in parallel with a carbon rod or unshorted dry storage.

Electric Conductivity↗
PubMed1989

A psychometric study of surface electrode placements for facial electromyographic recording: I. The brow and cheek muscle regions.

Despite the burgeoning literature using facial electromyography (EMG) to study cognitive and emotional processes, the psychometric properties of facial EMG measurement have received little attention. Two experiments were conducted to assess the reliability and validity of facial EMG as a measure of specific facial actions. In Experiment 1, two recording sites in the brow region were compared for their ability to differentiate facial actions hypothesized to be due to the activation of the corrugator supercilii from facial actions presumed to be due to the activation of proximate muscles (e.g. depressor supercilii, procerus, frontalis, levator labii superioris alaeque nasi, orbicularis oculi), and four sites in the infraorbital triangle were compared for their ability to differentiate facial actions hypothesized to be due to the activation of the zygomaticus major from facial actions presumed to be due the activation of proximate muscles (e.g. zygomaticus minor, risorius, buccinator, orbicularis oculi, orbicularis oris). Fifteen subjects were instructed to pose a series of facial actions while EMG activity was sampled simultaneously at all sites. In Experiment 2, 5 subjects returned to the laboratory for a more extensive investigation of surface EMG activity over the zygomaticus major muscle region. The results of this experiment confirmed the findings of Experiment 1. Overall, the results demonstrate that certain recording sites located over specific facial muscle regions are more sensitive and valid indices of particular facial actions than other nearby sites.

Adult↗