Fatigue during prolonged performance on a simple compensatory tracking task

Two basic activities are involved in radar operating, watchkeeping and target tracking. Deterioration of watchkeeping performance has been explained by a hypothesis which relates absence of sensory variation and failure to attend to one part of the display continuously (Broadbent, 1951). This paper describes a preliminary experiment to examine deterioration on a simple compensatory tracking task.

Twenty-one subjects were each tested for an uninterrupted period of two hours. They were required to keep a target correctly aligned by cranking a handwheel at a constant speed, and it was expected that failures to attend to the display would result in target deviations. Analysis of the results showed that both number of errors and mean duration of errors increased significantly in consecutive half-hour periods, and that there were large individual differences in performance.     

Gender-related sexual attitudes: Some crosscultural similarities and differences

We tested the hypothesis that males differentiate love and sex more strongly than females, and that the magnitude of this gender difference is augmented in homosexuals and diminished in married heterosexuals. American and Swedish subjects sorted statements describing behaviors of love, sex, and services into two piles on the basis of perceived similarity. The results of all three studies were consistent with the predictions. In addition, the findings suggest that Americans differentiate love and sex more strongly than Swedes.     

Racial differences in stress-induced cardiovascular reactivity and hypertension: current status and substantive issues

Essential hypertension is perhaps the number-one health problem of Black Americans. Research has indicated that stress-induced cardiovascular hyperreactivity may be a significant contributor to essential hypertension. The high prevalence of hypertension among Blacks suggests that this group, in comparison with Whites, may be particularly susceptible to cardiovascular hyperreactivity. The first portion of this article reviews research to date that has examined racial differences in resting and stressor-induced cardiovascular activity. The second half of this article overviews some critical methodological and conceptual issues involved in the study of racial differences in reactivity. These issues include the effects of Black-White differences in plasma renin levels and sodium excretion, the effects of experimenter race, and differences in perceptions of the laboratory environment. Additionally, the issue of racial group classification and the implications this has for interpreting Black-White differences in reactivity is discussed. Two perspectives on racial group classification, the genetic and the sociocultural, are addressed in some detail, and the relevance of each to research on racial differences in stress reactivity is presented.     

The need for power,brain norepinephrine turnover,and memory

Subjects were classified according to whether they were high or low in the need for Power and high or low in gain in 3-methoxy-4-hydroxyphenylglycol (MHPG), a putative index of brain norepinephrine (NE) turnover, after engaging in some tasks that involved memory for story content. Subjects who were high inn Power and in the index of brain NE turnover showed better recall of power-related facts than subjects low on both these characteristics, confirming an earlier finding, which suggests that the need for Power is subserved by a noradrenergic reward system in the brain.     

Modality-repetition and attentional effects on reflex blinking in infants and adults

The ability of a brief prepulse to inhibit reflexively elicited startle is a robust phenomenon in adults of several species but is weak or absent in infants. The possibility that afferent processing of the prepulse is inadequate in infants was tested by assessing the integrity of two other types of reflex modulation that occur in modality-specific paths, that is, attenuation by repetition of same-modality stimuli and enhancement by modality-selective attention. The reflex, measured by electromyographic activity of the muscle controlling blink, was elicited by intense light flashes or noise bursts preceded by brief acoustic or visual prepulses and delivered during attention-directing acoustic or visual foregrounds that evoked cardiac deceleration. Modality-repetition effects were evidenced by smaller peak blink magnitude and longer latency of blinking to same than to different modality pairs and did not differ as a function of age (4-month-old infants or college students). Attention effects were also seen in both infants and adults and, in accord with previous findings, were evident in magnitude for infants and latency for adults. Thus, immaturity in paths mediating these effects could not explain delayed development of prepulse inhibition. Other possibilities include delayed maturation of extrinsic inhibition or of transient-processing systems.