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Biomedical subjects

L E Stamps

Publications and source records attributed to L E Stamps.

14 recordsLinked to original sources
PubMed1988

Effects of caffeine withdrawal on motor performance and heart rate changes.

Heavy caffeine Users and Non-users were tested twice using a signalled reaction time paradigm, while heart rate was recorded. During the 7-day interval between the two sessions, the User group maintained normal caffeine intake for the first 5 days and abstained from caffeine during the last 2 days, which constituted a withdrawal period. The Non-users abstained from caffeine (as they usually do) during the entire 7-day period. The analyses of the reaction time (RT) data indicated no differences during Session 1 and a significant group difference during Session 2, with the Non-users exhibiting faster RT's. The Users exhibited no change between Sessions 1 and 2, while the Non-users showed a decrease in RT's (increased speed) across Sessions, which may be indicative of a practice effect. The analysis of the heart rate data from the 5-s period prior to the imperative stimulus yielded no differences during Session 1, and a significant group difference in Session 2, with the Non-users exhibiting larger decelerations. Across the two Sessions, the Non-users showed an increase in the magnitude of the heart rate deceleration, while the Users exhibited a decline in the size of the deceleration. Since the magnitude of heart rate deceleration has been interpreted as an index of attention, it appears that the Users were exhibiting less efficient attention during withdrawal from caffeine (Session 2) than were the Non-users. This conclusion is supported by the RT data, showing slower response times for the Users during Session 2, as compared to Non-users.

Adult↗
PubMed1988

The type A behavior pattern in children: relationships with performance on speed oriented tasks.

The Matthews Youth Test for Health (MYTH) was completed by teachers to evaluate 85 fifth- and sixth-grade boys. Type A and B groups of 20 boys each were selected based on MYTH scores. Each boy performed a signalled reaction time task and a perceptual search task. No performance difference was found between the Type A and B boys on the reaction time task. On the perceptual search task, each boy had to scan a set of pictures and report the number of "Snoopy's" seen in each picture. A group difference in response time was found, with the Type A boys having a mean of 5.98 s versus 7.87 for the Type B boys.

Child↗
PubMed1987

Relationships between the type A behavior pattern and phasic heart rate responses during a reaction time task.

Type A and B college students performed a signalled reaction time task with a 17-s fixed preparatory internal (PI) while heart rate was recorded. The analysis of the first half of the PI indicated a triphasic heart rate response (deceleration-acceleration-deceleration) to the warning signal, followed by a return toward baseline. No group differences were found. During the latter half of the PI, the Type B subjects exhibited a time-locked heart rate deceleration which reached its maximum at the second immediately prior to the onset of the imperative stimulus. The Type A subjects exhibited maximum deceleration earlier in the PI. These findings are consistent with previous work indicating that Type A's have difficulty maintaining their attention over relatively long PI's of reaction time tasks.

Adult↗
PubMed1986

A comparison of the effects of fixed versus variable foreperiods on anticipatory cardiac deceleration prior to an exercise task in grade school children.

Children's heart rate responses in anticipation of a signalled exercise task were examined. The use of fixed (15 s) vs variable (10, 15 or 20 s) preparatory intervals (PI) was compared. The analysis across all subjects indicated that the children exhibited a stable deceleration immediately prior to the exercise task. A difference was found between the fixed and variable PI's. During the period immediately before the exercise task, those subjects receiving the variable PI exhibited a decrease across trials in the size of the anticipatory heart rate deceleration. The children receiving the fixed PI showed an increase across trials in the size of the deceleration.

Attention↗
PubMed1980

Relationship between heart rate indices of the orienting response and birth weight in normal full-term newborns.

The results of this study indicate that birth weight in normal term infants is related to changes in heart rate in response to auditory stimulation. Only infants above the median in birth weight responded to stimulus onset and offset. They exhibited a change in response to onset from a heart rate acceleration (defensive response) on the 1st trial to heart rate deceleration (orienting response) on later trials. The response to stimulus offset was a deceleration. Those infants below the median in birth weight showed no significant responses to onset or offset.

Birth Weight↗
PubMed1979

Differential effects of state and trait anxiety on heart rate responses and reaction time.

College students were tested on 10 trials of a reaction time task, using a variable interval warning signal, while heart rate was recorded. Subjects were divided into high and low anxiety groups using a median split based on their scores on a modification of the trait scale of the State-Trait Anxiety Inventory. The low anxiety group exhibited faster reaction times, shorter latency heart rate deceleration following warning signal onset, and a more consistent deceleration immediately prior to the respond signal than the high anxiety group. When the same subjects were divided into groups according to state anxiety, no group differences were found in either heart rate or reaction time. In Part II of the study, subjects listened to six 15 s presentations of a 70 dbA, 250 Hz tone. No group differences in heart rate responses to the tones were found for either state or trait anxiety groups.

Adolescent↗
PubMed1979

The Mosher Guilt Scales: a construct validity extension.

The three subscales of the Mosher Guilt Scales (sex guilt, hostility guilt, and morality conscience guilt) and several personality and attitude measures were ad ministered to college subjects in an effort to examine the construct validity of the Mosher Guilt Scales. The variables that were compared with the guilt subscales were hostility, anxiety, religious orthodoxy, self-esteem, and the importance of religious and economic values in one's life. The results indicated that both the construct validity of the Mosher Guilt Scales and the need for the continued use of its three subscales were supported. Among the most crucial findings of the study were that both of the religiosity measures were positively correlated with all three guilt subscales, and that economic values were negatively correlated with both sex guilt and morality-conscience guilt.

Journal Article↗
PubMed1979

Guilt and shyness: a profile of social discomfort.

The Mosher Guilt Scales, the Stanford Shyness Survey, and measures of anxiety, hostility, and self-esteem were administered to 54 college females in an effort to clarify the nature of the personality problems that beset shy and guilty persons in social situations. As was hypothesized, it was found that shy people also tended to be guilty. This complicates attempts to understand the nature of the problems with which shy and guilty persons must cope. In addition, it was found that both shy and guilty people tended to be high in trait anxiety, and low in hostility and self-esteem. Thus the profile of a shy, guilty person is that of an individual who is uncomfortable with her own feelings, actions, and beliefs across a variety of social situations.

Anxiety↗