Birgitta Post

Psychophysiological reactions to understimulation and overstimulation

Abstract Catecholamine output, heart rate, and performance efficiency were examined in 28 Ss during two contrasting stimulus conditions, one of understimulation, and one of overstimulation. During understimulation the subject spent 3 hr performing a vigilance task, and during overstimulation he was exposed for the same time period to a complex sensorimotor test. Both understimulation and overstimulation produced a significant increase of adrenaline and noradrenaline release as compared with a control condition involving a medium amount of stimulation. Subjects who excreted relatively more adrenaline performed significantly better during understimulation, whereas subjects with relatively lower excretion rates of adrenaline tended to perform better under overstimulation. When performance efficiency was related to heart rate it was shown that high-heart rate subjects performed better during understimulation, while low-heart rate subjects performed better during overstimulation.

Behavioural and physiological effects of cigarette smoking in a monotonous situation.

Sustained performance in a visual reaction time test was examined in 12 moderate smokers. In a control condition without smoking, efficiency decreased over time. In a, condition, where 3 cigarettes were smoked at 20-min intervals, the subjects were able to maintain their initial level of performance throughout the session, mean reaction times being significantly shorter in the smoking than in the control condition. Smoking produced a significant increase in adrenaline excretion and heart rate.

Dosage and time effects of cigarette smoking

SummaryEffects of cigarette smoking were examined in eight healthy habitual smokers. Comparisons between effects on catecholamine excretion produced by 2, 4, and 6 cigarettes, smoked within a 2-hr period, showed a progressive increase in adrenaline excretion with number of cigarettes, while noradrenaline excretion was not noticeably affected. Comparisons between smoking and control conditions showed effects on hand steadiness, skin temperature, heart rate, and blood pressure. Dose- and time-response curves indicated that the relatively largest effect was regularly produced by the first cigarette, while the 2nd to 6th cigarette produced progressively smaller changes.

Physiological and Subjective Reactions to Different Physical Work Loads.

Catecholamine excretion, cardiovascular functions, and subjective effort were studied in 10 healthy male Ss in a control condition and in three experimental sessions in each of which 5 successive 6-min. tests of either 150, 450, or 750 kpm/min., were performed on a bicycle ergometer. Catecholamine-excretion rates remained close to control levels at the lower work loads, while the highest load induced a significant increase in both adrenaline and noradrenaline output. Heart rate, systolic pressure, and subjective effort increased consistently with increasing work load.

Changes in behavioral and physiological activation induced by cigarette smoking in habitual smokers

Performance in tasks on visual simple- and choice-reaction time was studied in six healthy habitual smokers. Results from a non-smoking condition, and a condition in which each subject smoked four cigarettes, indicated that smoking had a beneficial effect on performance efficiency in both tasks: (a) simple-reaction time increased over time in the non-smoking condition, but remained at the same level in the smoking condition, and (b) choice-reaction time increased slightly in the non-smoking condition, and decreased in the smoking condition. The difference between conditions was statistically significant for simple-reaction time. Hand steadiness was impaired by smoking. Heart rate and systolic pressure increased in the smoking condition, while catecholamine secretion remained relatively unaffected by smoking. Self-estimates of wakefulness and mood showed that smoking was judged to have favourable effects.

Catecholamine Output during and after Acute Alcoholic Intoxication

Catecholamine secretion was examined in 16 healthy Ss after intake of 1.43 g alc/kg body wt. Adrenaline and noradrenaline output were both significantly increased during acute intoxication, and adrenaline remained at an elevated level during the post-alcohol phase.

Effects of a Depressant Drug as Modified by Experimentally-Induced Expectation:

Objective and subjective reactions to drug and placebo treatments were studied in 15 healthy Ss under three conditions: (1) 200 mg. Pentobarbitone introduced as a depressant drug, (2) 200 mg. Pentobarbitone introduced as a drug the actions of which were not known to E, and (3) a placebo introduced as a depressant drug. Mean time-response curves showed that pulse rate, objective and subjective reaction speed, and subjective wakefulness were decreased by all treatments. The greatest effects were produced by Pentobarbitone introduced as a depressant while Pentobarbitone alone was, on the whole, less effective than the placebo introduced as a depressant drug.