Reversal of genetic homeostasis in laboratory populations of Drosophila melanogaster under long-term selection for geotaxis and estimates of gene correlates: evolution of behavior-genetic systems

Among Drosophila melanogaster, divergently selected for geotaxis intermittently over 600 generations (28 years), about 80,000 animals have been analyzed behavior-genetically. Each major chromosome pair from two lines was isogenized on an unselected isogenic background. Measurement of their behavioral effects revealed the relative magnitudes II greater than III greater than X for the negatively geotactic (high) line and X greater than III greater than II for the positively geotactic (low) line. When reversing selection for the now phenotypically stable high and low lines and then repeatedly relaxing the reversals, a new genetic homeostasis in the low line was indicated by the return of the reversed-line average scores towards the low extreme; that is, the low line has attained a stable equilibrium for positive geotaxis, an uncharacteristic behavior and an effect not seen before 1979. This change suggests the recent evolution of a new coadaptation among genes. Although not as conclusive, a similar genetic interpretation is suggested for the high line.     

Coping with the exposure to torture

This paper describes approaches taken at the International Rehabilitation and Research Centre in Copenhagen to helping torture victims and their families cope with the exposure to and aftermath of torture.     

Memories of a bicycle tour

One person's memories of a 47-day bicycle tour of Scandinavia were tested 3–4 months later. The tests assessed frequency, spatial, and temporal knowledge of events. Results indicated that frequency judgements were based on some combination of counts of discrete event memories and a general impression of the tour. Episodic memories showed clear variation as a function of where events had occurred, and judged and actual locations of episodes were strongly related. In fact, knowledge of the week in which something had happened appeared to hinge on where in a sequence of locations it was thought to have taken place. The apparent dependence of temporal judgements on spatial information is consistent with other findings in the literature indicating that temporal memories about past events are derived from a variety of other associated information, much of which is temporally referenced.     

The development of sex differences in young children's activities at home: The effect of the social context

Randomly scheduled spot observations of 83 zero to six-year-old American middle-class children were used to investigate factors affecting the development of sex differences in young children's activities in and near their home. Sex and age differences in children's typical play and nonplay activities and in the people with whom they did activities were examined. The results showed that there were fewer sex differences in children's activities, activity partners, and general social settings than expected. Girls spent more time engaged in housework and school-related activities than boys, while boys spent more time in social gross motor play with other children and in self-care activities than girls. Children spent a surprisingly large amount of their time with members of their immediate family — particularly their mother and one other sibling. Boys and girls did not differ, however, in the time they were in settings or doing activities with their father, with their mother, or with same-or mixed-sex child groups.This research was supported by an award to the author from the Wisconsin Alumnae Research Foundation at the University of Wisconsin — Madison. The author would also like to acknowledge the research and editorial assistance of Daniel J. Walsh. In addition, Aletha Huston, Beatrice B. Whiting, and Gary G. Price provided valuable advice on this and earlier versions of this paper.     

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.     

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.