PSYCHOPHYSIOLOGICAL REACTIONS TO TWO DIFFERENT PLACEBO TREATMENTS

Reactions to a placebo introduced either as a depressant or as a stimulant drug were examined in 16 healthy female subjects. Comparisons between pre- and post-placebo measurements showed that the two treatments produced marked effects in opposite directions: (1) the 'depressant' placebo produced a statistically significant decrease in pulse rate, blood pressure, objective and subjective reaction speed, as well as significant effects on subjective mood in the expected directions, and (2) the 'stimulant' placebo produced opposite and significant changes in all variables. The subjective reactions were, on the whole, more pronounced than the effects on performance and physiological functions.     

AUTONOMIC INDICES OF HABITUATION TO COMPLEX AND SIMPLE STIMULI

Skin conductance and heart rate were continuously recorded in 8 subjects repeatedly exposed to a perceptual-conflict test and to auditory signals. (1) Both complex and simple stimuli gave rise to a pronounced increase in skin conductance, the magnitude of response decreasing with number of repetitions. For both types of stimuli a linear relationship was obtained when GSR, measured as the change in log conductance, was plotted against the logarithm of the stimulus number. (2) Each presentation of the conflict test increased heart rate, magnitude of change decreasing approximately linearly with number of trials.     

SUBJECTIVE TIME AS AFFECTED BY GRAVITATIONAL STRESS

Subjective time as affected by positive radial acceleration in a human centrifuge was studied by a modification of the method of ratio production. Auditory signals (1–20 sec.) were used as stimuli. The results showed a marked change in subjective time during gravitational stress. Subjective time, as measured by the methods employed, was a positively accelerated function of objective time and the positive acceleration was enhanced during centrifugation. The demonstrated change in time experience was caused by a difference in retention of preceding time intervals, retention being impaired during centrifugation.     

THE INFLUENCE OF INTENSITY AND DURATION OF ELECTRICAL STIMULATION ON SUBJECTIVE VARIABLES

The unpleasantness and subjective duration of an A.C. current of 50 c/sec applied to two fingers was scaled by subjects using the method of magnitude estimation. Stimulation was varied with regard to both intensity and duration. It was found that (1) unpleasantness increased logarithmically with stimulus duration, (2) unpleasantness was a power function, with the exponent 1.5, of stimulus intensity, (3) subjective duration was essentially linearly related to stimulus duration, and (4) subjective duration increased logarithmically with intensity of stimulation.     

Experiments on habit reversal in the white rat following electro-convulsive treatment

Rats in a T-maze were taught two opposite habits successively, the first being heavily over learned compared to the second. One group of 14 rats was then given a series of 6 electroconvulsive shocks. The control group of 11 rats underwent a dummy procedure.

Tested subsequently the control group maintained the second habit but among the shocked animals some adopted the second habit and some the first. This was no evidence of habit reversal, however, for the behaviour of the shocked animals at the choice point was not distinguishable statistically from random behaviour.

The data of earlier workers are re-examined and, in all cases, animals said to have undergone habit reversal act as if at random.     

TIME RELATIONS OF OBJECTIVE AND SUBJECTIVE REACTIONS TO D-AMPHETAMINE AND PENTOBARBITONE

Successive measurements of pulse rate, blood pressure, objective and subjective reaction speed, and six mood variables were made on 12 healthy subjects during 135 min. periods following the intake of either 15 mg d-amphetamine, 200 mg Pentobarbitone, or a placebo. It was shown that (1) the two drugs had essentially opposite effects on all objective and most subjective variables; (2) after d-amphetamine subjective effects appeared earlier and reached their maximum more rapidly than objective effects; (3) both types of reaction were less pronounced after Pentobarbitone than after d-amphetamine under the present dose conditions; and that (4) after Pentobarbitone maximum objective effects were attained at an earlier point in time.     

Immediate effects of cigarette smoking as related to different smoking habits.

A questionnaire concerning interactions between the need to smoke and the external situation was used to select 8 "low-arousal smokers" and 8 "high-arousal amokers." The former were smokers who generally experienced their strongest need to smoke in low-arousal situations, characterized by e.g., monotony or boredom, while the latter experienced their strongest need to smoke in high-arousal situations, characterized by, e.g., anxiety or excitement. Members of each group were examined under smoking and nonsmoking conditions in a low-arousal situation, i.e., performing a vigilance-type sensorimotor task, and in a high-arousal situation, i.e., performing a complex sensorimotor task. It was shown that the two groups reacted differently to smoking in the two situations. In low-arousal smokers performance and general well-being were favourably affected by smoking in the low-arousal situation only. Conversely, performance and well-bing of the high-arousal smokers were enhanced by smoking in the high-arousal situation only.