Assessment of the relative importance of S+ and S− in rats using differential training on intercurrent discriminations

The present studies assessed the degree of stimulus control exerted by S+ and S? without confoundings of stimulus novelty and stimulus ambiguity. In Experiment 1, rats were trained on two intercurrent simultaneous discrimination problems with nine times more training given on one than the other. Then the animals were given transfer tests with re-paired stimuli. The results showed that S? exerts greater stimulus control than S+ in a two-choice simultaneous discrimination. Experiment 2 provided a test of the possibility that the relative degree of control by S? varies with different amounts of training. Three groups were trained on two intercurrent simultaneous discrimination problems; each group was given 7, 11, or 15 times more training on one problem than the other. Then transfer tests were given with re-paired stimuli. Again the results showed that S? exerts greater stimulus control than S+ in a two-choice simultaneous discrimination.     

THE DEVELOPMENT OF KNOWLEDGE CONCERNING WRITTEN ARITHMETIC: A CROSS-CULTURAL STUDY

This study is concerned with the manner in which Western mathematics is assimilated by children raised in traditional African cultures. It was predicted that after an initial period of difficulty in learning school arithmetic, African children (Baoulé and Dioula from the Ivory Coast) acquire basic concepts, develop invented strategies, and make errors similar to those of American children. Further, it was predicted that Dioula children, since they are members of a commercial culture, perform at a somewhat higher level than the Baoulé, members of a farming culture which does not seem to stress computational activity. To investigate these hypotheses, American, Baoulé, and Dioula children at two age levels were given a variety of arithmetic problems involving basic skills (e.g., reading numbers), number knowledge (e.g., place value), and calculational abilities (e.g., written computation). The results showed that, in general, older African and American children (fifth- and sixth-graders) were quite similar in all respects. The only large and significant differences occurred in the case of younger children (second- and third-graders). At this level American children generally performed at a higher level than Africans, as predicted, and Dioula occasionally at a higher level than Baoulé, also as predicted. At the same time, qualitative aspects of African and American children's performance were similar: for example, both groups made the same types and proportions of errors in written calculations. The results generally support the hypotheses and can be explained in terms of both educational and cognitive factors.     

External memory: High speed,low speed,and no speed

This paper describes potential constraints on the selection of external memory devices (stimulus sources) and suggests options available to the would-be user of such systems for estimating research requirements and the functional parameters of the available external memory devices.     

Social support, stress, and depressive symptoms among the elderly: test of a process model.

Effects of social support, negative life events, and daily hassles on depressive symptoms were assessed in 301 adults aged 65 or older, in person 3 times at 6-month intervals and by mail questionnaires every month over a 12-month period. Initial social support predicted severity of depressive symptoms 12 months later. Social support and initial levels of depressive symptomatology predicted number of daily hassles but not number of major life events. Effects of social support, depression, and major life events on the incidence of daily hassles remained significant without the inclusion of hassles reflecting depressive symptomatology or problems in relationships or whose content overlapped with major life events. Daily hassles mediated the effects of major life events on subsequent depression. Results did not differ for men and women. Implications for models of the relations among social support, stress, and depression are discussed.     

Relationships between judgements of the complexity,pleasingness and interestingness of music

Forty unfamiliar, one-minute samples of modern jazz were rated by 132 undergraduates for judged complexity, pleasingness and interestingness, in a between-subjects design. Pleasingness and interestingness were positively correlated and both were decreasing linear functions of complexity, although the correlation between interestingness and complexity was low and only marginally significant. It appears that pleasingness acts as a suppressor on the interestingness/complexity correlation: with pleasingness partialled out the correlation was positive and highly significant. Partialling had only small effects on the other correlations. Results suggest that techniques used previously to study non-musical stimuli may also be applicable to music.     

Electrophysiological and behavioral indicants of selective attention to multifeature gratings

The mechanisms underlying selective attention to gratings consisting of a particular conjunction of spatial frequency and orientation were investigated by means of both visual evoked potential (VEP) and behavioral measures. The effects of selective attention upon the VEP indicated two general types of selection processes: one which is specific to the features contained in the relevant gratings and is most pronounced approximately 225 msec post-stimulation, and another which is specific to the conjunction of features defining the relevant grating and is most pronounced 250–375 msec following the presentation of the stimulus. The behavioral responses primarily reflected this latter, or grating-specific, attentional process. The results are discussed in terms of the role of sensory feature channels in mediating selective attention to visual stimuli and are related to various information processing models of visual pattern selection.