RELATIONS BETWEEN PREDICTION- AND ESTIMATION-RESPONSES IN CUE-PROBABILITY LEARNING AND TRANSFER

B auer M arianne Relations between prediction- and estimation-responses in cue-probability learning and transfer. Scand. J. Psychol ., 1972, 13 , 198–207. —Comparisons were made between prediction- and estimation-responses, preceded by training with different types of responding and when task probabilities were shifted. The main results were: ( a ) differential effects of procedure of learning and shift in task structure on predictions and estimates support the hypothesis of two different processes, ( b ) estimates as indicators of probability learning reflect traits assumed to characterize the perception process, viz. sensitivity to shifts in probabilities, and robustness against influence from procedure of learning, and ( c ) prediction-responses were affected in the direction of more extreme responses by simultaneous estimation, which result strengthens the supposition that probability estimates are insufficient as indicators of the complete perception process in a prediction task.     

Polydipsia induced in the rat by a second-order schedule

Drinking was studied in rats pressing a bar on a second-order schedule in which every third completion of a 1-min fixed interval was followed by food presentation. A brief flash of light signaled the completion of each fixed-interval component. The rats drank not only after the food presentations but also after presentations of the light flash alone. A high rate of steady drinking followed intervals terminated by a food presentation. Drinking that followed intervals terminated by a light flash alone was of comparable rate, but characteristically interrupted by bar pressing. When 250-mg food pellets were used instead of 45-mg pellets, both drinking and bar-pressing rates increased substantially.     

Frequency-selective detection at three signal amplitudes

Using the probe-signal method, frequency-response characteristics were obtained for four Os detecting signals nominally of only 1000Hz under three signal-amplitude conditions: E/N_o=10.0, 12.6, and 15.8. Detection of 1000-Hz signals decreased systematically with signal-amplitude decreases, but signals at 850 Hz and at 1150 Hz were detected at or near the chance level during all signal-amplitude conditions. From the detection performance data, the detectability was inferred for four probe-signal frequencies relative to that of 1000-Hz signals for each of the amplitude conditions. From the curvesofrelative detectability, hal[-detectability bandwidths were estimated. Neither the relative detectability curves nor the half-detectability bandwidths indicate any systematic change in the frequencyselectivebehavior of the auditory O across the signal amplitudes used.     

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.