The effect of thematic content on the ‘Wason selection task’

This paper concerns the differential effects of use of ‘thematic’, rather than abstract (symbolic), content on the ‘Wason selection task’. An effect of thematic content has been reported several times, originally by Wason & Shapiro (1971), but Manktelow & Evans (1979) report five experiments that failed to obtain an effect and argue against the validity of the content effect in general. However, it is pointed out that four of their experiments use a novel content and that there are previous reports of non-effective content in the literature. It is concluded that a particular type of thematic content cannot be treated as a ‘random sample’ of thematic content in general, and that their argument thus rests upon their failure to produce an effect of the specific (’towns and transport’) content used by Wason and Shapiro. This produces an essentially empirical controversy which is settled in two ways. First, Manktelow and Evans’s criticisms of two previous replications are shown to be misleading. Second, an experiment is reported that exactly copies the Wason and Shapiro design and produces a significant effect of content. It is concluded that the Manktelow and Evans result most probably was due to a Type 2 error. Finally, a hypothesis is developed to account for both the effect of certain types of content and the lack of effect of others, including that used in Manktelow and Evans’s first four experiments.     

Two subjective scales of number

The way in which the apparent magnitude of numbers grows with their absolute magnitude was measured with a modified version of the direct technique Marks and Slawson (1966) used to determine the psychophysical exponent for loudness. This modified technique required subjects to estimate how evenly and randomly a sequence of integers appeared to sample the numerical continuum. The results indicate that the apparent magnitude of numbers increases with a decelerated power function of their arithmetic magnitude when a series samples from an open-ended range. However, when an upper boundary of the range is specified, the subjective scale seems to be linear. Random productions of numbers parallel the results found with judgments of presented sequences. The two scales of number provide the basis for an interpretation of the difference between magnitude and category scales: that subjects use numbers differently when the response scale is open-ended Imagnitude estimation than when it has a fixed upper limit tcategory scale. Given the assumption that subjects use numbers in this way in the two tasks, the qualitative relation between magnitude and category scales is predicted.     

Foveal diplopia thresholds and fixation disparities

Comparison of the magnitude and intrinsic spread of foveal diplopia thresholds with the accuracy of ocular alignment as determined with a subjective alignment method shows that: the accuracy of alignment in the vertical direction (within 1–2 min) is remarkably good and much better than in the horizontal direction; the largest disparities occurring due to restricted alignment accuracy are usually substantially smaller than the foveal diplopia thresholds; interindividual variability in the magnitude of foveal diplopia thresholds is not due only to interindividual variability in the alignment accuracy; and the spread of foveal diplopia thresholds exceeds the spread of ocular alignment, which implies that the noise in the foveal disparity domain is not only due to the restricted alignment accuracy but also to sensory processes. Finally, the data confirm that, unlike the case with diplopia thresholds, the spread of stereoscopic thresholds is not affected by the restricted alignment accuracy.     

Integrality over different paradigms: Card sorting and two-stimulus matching

Orthogonal interference—indicating the cohesiveness between geometrical dimensions—was examined using two separate tasks: (1) card sorting and (2) two-stimulus matching requiring same/different responses. The card-sorting results of the present experiment were contrasted with the results of our previous research (1977, 1979) which used the two-stimulus matching task. Results were generally similar in that the orthogonal interference and, consequently, the degree of integrality/separability were the same for both tasks. Evidence was found for the emergence of a new nominal dimension. This and other results are only compatible with a weaker form of the global-to-local hypothesis of perceptual processing.     

Antagonistic effects of adjacency and apparent speed in induced movement

Two experiments concerning induced movement are reported. The hypothesis was that when outline inducing frames were used, object-relative displacement was modified by two variables, adjacency and apparent speed. Adjacency is directly related to the magnitude of induced movement. Small outline frames are high in adjacency, and so small frames should be powerful generators of induced movement. On the other hand, several investigators have found the speed of the inducing frame to be inversely related to the magnitude of induced movement. It is hypothesized here that this effect of speed was determined by apparent speed (not real speed), and if so, since small objects appeared to move faster than large ones, a small outline frame should be a relatively weak generator of induced movement. In the first experiment, this hypothesis was tested using single inducing frames. In the second experiment, this hypothesis was tested using two inducing frames presented simultaneously. The implications of these experiments were discussed with regard to other theories of induced movement.     

Sharing behavior and racial preference in children

Three groups of white children, 43 preschoolers and first-graders, 46 third-graders, and 44 fifth-graders, were asked to choose either a white child or a black child as a recipient of sharing and also as a companion for several social interaction situations ordered for social distance. The preschoolers and first-graders preferred to share and interact socially with the white child. The third-graders and the fifth-graders displayed a weaker preference for the white child over the black child on the sharing task, no preference in situations of high social distance, and a preference for the white child in situations of low social distance. The results from ancillary measures suggested that the choices of the younger children were motivated by a generalized color preference but that the choices of the older children were guided by an awareness of the social meaning of racial categories.The investigation was supported by the Research Advisory Council of East Tennessee State University.     

Behavior of depressed subjects in problem solving groups

This study investigated leadership selection in groups in relation to level of depression of group members. On the basis of MMPI-D and DACL scores 66 subjects were organized into groups of six to eight people consisting of all depressed, all nondepressed, or half depressed and half nondepressed subjects. Subjects performed a problem solving task alone and in groups and completed a questionnaire on leadership choice and group performance. Results indicate that nondepressed group members talked more frequently, were rated as more important contributors, and were selected as leaders more frequently than depressed members. In addition, mixed groups were perceived as more efficient and enjoyable by group members than the unmixed groups. There were no significant differences between depressed and nondepressed subjects on performance of the problem solving task whether working alone or in groups. Results were discussed in relation to other literature on the interpersonal behavior of depressed persons.