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T J Harbin

Publications and source records attributed to T J Harbin.

9 recordsLinked to original sources
PubMed1989

The relationship between the type A behavior pattern and physiological responsivity: a quantitative review.

Researchers have attempted to specify the process linking Type A behavior to coronary artery disease. Increased cardiovascular and neuroendocrine reactivity in Type A individuals has been proposed as the intervening mechanism. There have been several previous reviews of the research relating Type A behavior to physiological reactivity. The authors' conclusions have been equivocal; some assert that Type A persons are more reactive, whereas others find no evidence for such a conclusion. In this report, meta-analysis, an alternative to the traditional narrative review, was employed to provide a quantitative evaluation of the relationship between Type A behavior and physiological reactivity. Results indicated that: 1) Type As respond to cognitive and psychomotor stimulus situations with greater heart rate and systolic blood pressure responses, 2) this relationship is not evident in females, 3) the relationship is more evident for some cognitive tasks than for others, and 4) the strength of the relationship depends upon the instrument used to assess Type A behavior.

Adult↗
PubMed1986

The effects of age and attention upon reflex inhibition.

Previous research has suggested that reflex amplitude may be influenced by the direction of attention. The purpose of this investigation was to evaluate the effects of an attention-demanding visual reaction time task upon the elicitation of reflexes and modification of reflexes by an antecedent prestimulus in young and elderly adults. In young subjects, eyeblink inhibition was augmented by the task, yet there was no effect upon overall reflex amplitude. Elderly subjects showed no effect upon reflex inhibition while overall reflex amplitude was diminished by the task, independent of the amount of inhibition. In young subjects, the prestimulus also accentuated the initial decelerative component of a biphasic heart rate response. The reaction time task also served to augment this deceleration. The elderly heart rate response was not affected by the experimental conditions. These results provide evidence that reflex inhibition is modulated by attention. However, the relationship is complex, developmentally sensitive, and involves generalized attentive processes as well as selective attention toward specific stimuli or sensory modalities.

Adolescent↗
PubMed1985

Relationships among age, sex, the type A behavior pattern, and cardiovascular reactivity.

Most investigations of Type A behavior and cardiovascular responsivity have used age-homogeneous, male samples. In this study, heart rate (HR) and blood pressure responses were obtained from men and women, age 27 to 70, during mental arithmetic and a visual discrimination task called the Matching Familiar Figures test (MFF). Both tasks produced HR deceleration in Type A women and acceleration in Type B women, responses that decreased with age. Men's responses were not related to Type A behavior or age. Systolic pressure decreased in response to the MFF. This response became larger with age in Type Bs and smaller in Type As. Diastolic pressure also decreased during the MFF. Response amplitude increased with age in Type Bs but was unrelated to age in Type As. The results of this study indicate that the relationship between cardiovascular responding and Type A behavior is complex and may be different for men and women and for persons of different ages.

Adult↗
PubMed1984

Differences in the late components of the event-related potential due to age and to semantic and non-semantic tasks.

Recent work in event-related potentials (ERPs) has revealed differences between ERPs elicited during the performance of semantic and nonsemantic tasks. This experiment examined age differences in the late components of the ERP as a function of these tasks. Young and elderly males were presented with 5-word strings on each trial. The subject's task was to decide whether or not the fifth word matched the other four. In one condition, the first 4 words were identical to one another and the fifth word was either the same or different. In the other condition, the first 4 words were different from one another but were drawn from from the same semantic category. The fifth word was either from the category or from a different category. Matches occurred in 15% of the trials and mismatches in 85%. The ERP to the fifth word was analyzed. All ERPs evidenced a late positive component (LPC), the latency of which was greater for the Category task and for mismatches. LPC amplitude was greater in the Identity task. In addition, young subjects' LPC amplitudes were greater for matches than for mismatches, whereas the reverse was true for the elderly. In agreement with previous research, our results indicated that an N400 wave is evident only in response to semantic incongruity and that variables affecting late positive activity seem to be independent of those producing N400. The N400 wave was seen at a greater latency in the elderly. Our results extend previous work (e.g., Kutas and Hillyard 1980) by finding an N400 in a semantic context other than sentences, and in concluding that this component is relatively insensitive to stimulus frequency.

Adult↗
PubMed1978

Influence of contextual variables on blood pressure in the elderly.

This research evaluated determinants of blood pressure in elderly subjects. Measurements were obtained from 30 subjects in three contexts; in the home measured by the subject, in the home measured by the experimenter, and in a psychophysiological laboratory measured by the experimenter. Four measurements were obtained in the two home conditions and two were obtained in the laboratory condition. For systolic blood pressure, the effects of condition, repeated measurement, and order of treatment presentation were significant. For diastolic blood pressure, the effect of condition was significant. A comparison of sample variances revealed greater variances for systolic blood pressure. It was concluded that initial blood pressure measurements obtained in a laboratory should be regarded as distinct from those obtained later, as the early measurements may be subject to elevation imposed by the context. Due to differing patterns of results for systolic and diastolic pressures as well as differences in variability, it was concluded that there exist conceptual problems with a construct such as mean arterial pressure.

Aged↗
PubMedDate not supplied

The effects of low-level carbon monoxide exposure upon evoked cortical potentials in young and elderly men.

The neurophysiological effects of acute, low-level carbon monoxide (CO) exposure are not well known. This experiment investigated the effects of a 5% carboxyhemoglobin level upon two indices of neurophysiological function, reaction time and the late positive component of the visual evoked potential in young and elderly men. Results indicated (1) no effects of CO upon any of the neurophysiological indices and (2) greater absorption of CO by young than by elderly men. These results, along with those of other studies, indicate that acute, low-level CO exposure is probably not neurotoxic, in normal, healthy men.

Adolescent↗
PubMedDate not supplied

The late positive component of the evoked cortical potential: application to neurotoxicity testing.

There is an urgent need for efficient, non-invasive measures of neurotoxic insult in humans. The late positive component (LPC) of the event-related cortical potential may be such a measure. The latency and amplitude of the LPC have been related to both memory and response speed, two aspects of behavior which are indicators of neurological status. The LPC has been found to be altered in cases of known neurophysiological insult, including Alzheimer's disease, cerebrovascular disease, Parkinson's disease, surgical and traumatic damage, hyperkinesis, chronic alcoholism, mental retardation, and in schizophrenia. Further development of the LPC as a possible indicator of both the cognitive impairment due to neurotoxic substances as well as the site of neurological damage is warranted.

Cognition↗