IQ and social class

A brief overview is given of the nature-nurture debate elicited on the basis of Arthur Jensen's article concerning group differences in IQ test results published in 1969.Sandra Scarr-Salapatek found that the contribution of genetic variance in IQ test results tended to be larger in a more stimulating environment and proportionately smaller in a disadvantaged environment. This finding has been tested on data from a Swedish twin study. A comparison of within-pair similarity for MZ and DZ twins with varying social background has been made. Genetic variance seems to account for a greater proportion of the variance in IQ test scores in social group I and II compared to social group III. This is in accordance with the conclusions drawn by Scarr-Salapatek and thus tend to support the above-mentioned hypothesis. It therefore seems as though the potentially restricting effects of working class conditions for the development of the kind of abilities measured by conventional IQ tests would tend to reduce the degree to which genetic differences are expressed. More stimulating environmental opportunities, on the other hand, tend to allow a greater range of such differences in the middle and higher social classes.     

Developmental trends in cue utilization for attributional judgements

Fourth through twelfth graders of both sexes were tested for developmental trends in making causal attributions for success and failure and in using past history, social comparison, and importance information in making their attributional judgements. Results suggested that basic information processing rules had already developed by the fourth grade but that children continue to develop and become more consistent in applying these rules. Sex differences indicated that girls were more defensive generally in not taking responsibility for their outcomes by attributing them externally.     

The nature of the task-stimulus interaction in the tachistoscopic recognition of kana and kanji words

To investigate the nature of the task-stimulus interaction in tachistoscopic recognition of kana and kanji, right-handed normal subjects performed two phonological tasks and two visual tasks. In the phonological tasks, the subjects compared the members of a pair of kana or kanji appearing in the right or left visual field on the basis of phonological identity; while in the visual tasks, they compared the members of a pair of kana or kanji on the basis of visual identity. The results showed a significant Visual Field × Task interaction as well as a significant Task × Stimulus interaction, indicating that both the type of stimuli and the nature of task demands contribute importantly to the determination of visual field asymmetry and hence the relative participation of each hemisphere.     

Capacity and strategy for syntactic comprehension after left or right hemidecortication

The left and right hemispheres perform different encoding and decoding operations on a syntactically complex sentence in order to identify its meaning. Hemispheric asymmetry for syntax involves not only variations in capacity, but also differences in the strategy used to effect similar language performance.     

The effect of mere presence on social facilitation: An unobtrusive test

An unobstrusive experimental manipulation was used to test the hypothesis that the mere presence of others can influence an individual's performance. A task was employed for which there were no clear performance criteria, and which was very unlikely to engender evaluation aprehension. Performance times on this task (dressing and undressing in familiar and unfamiliar clothing) were compared for subjects working alone, in the presence of a passive inattentive person, and in the presence of an attentive spectator. In contrast with the Alone condition, both social conditions (Audience and Incidental Audience) enhanced performance on the well-learned aspects of the task (dressing and undressing with one's own clothing) and hindered performance on the more complex aspects (working with unfamiliar clothing). It is concluded that the mere presence of others is a sufficient condition for social facilitation and social interference effects.     

Changes with age in two components of visual search speed

Subjects aged 8, 10, 12, and 18 years participated in two visual search tasks. In one task the rate of visual search reflected the speed of preattentive localization processes, and in the other task it additionally reflected letter identification process speeds. The data revealed that localization processes become faster from ages 8 to 12 and remain stable thereafter, and that identification processes increase in speed primarily from ages 8 to 10. Performance on a subsequent recognition task indicated that subjects of all ages were employing a similar encoding strategy during visual search. Furthermore, subjects retained general information about the features of irrelevant background letters even though recognition accuracy for more specific information about letter names was not high. The finding that localization and identification processes have different rates of development confirms the hypothesized distinction between the two and implies that developmental studies of visual scanning speed must focus upon changes in the relationships among various processes or component skills throughout development.     

Intelligence and the processing of stimulus structure

It has been demonstrated in a number of experiments that the difficulty level of several performance type intelligence test tasks is determined directly by stimulus and task variables that vary the information to be processed. The variables are quantifiable. The implications of these findings for intelligence and the problems of an experimental approach to the measurement of intelligence are discussed.