THE DEVELOPMENT OF STRATEGIES IN EMBEDDED FIGURES TASKS*

The starting point of the investigation was the field dependence-independence construct as measured with the Embedded Figures Test of H.A. Witkin. An overview of the research on the information-processing strategies in solving the items of this test was converging into a theory in which strategies for a successful solution can be located on a bipolar dimension with at one extreme a simultaneous strategy and at the other extreme a successive strategy. A new administration procedure for evaluating the use of four solution strategies was developed: the simultaneous, the successive, the extemalized-successive and the global-manipulatory strategy. Based on the prediction that the use of strategies was related to sex and age, we carried out an experiment involving groups of ten boys and ten girls of 5, 6 and 7 years of age, who were given eight tasks with the new administration procedure. No. significant difference was found between boys and girls. However, significant differences existed in strategy profiles in six of the eight tasks between the three age groups.     

Visual perception of surface curvature: psychophysics of curvature detection induced by motion parallax

The continuous approach to optic-flow processing shows that the curvature of a moving surface is related to a second spatial derivative of the velocity field, the spin variation (Droulez & Cornilleau-Pérès, 1989). With this approach as a theoretical framework, visual sensitivity to the curvature of a cylinder in motion was measured using a task of discrimination between cylindrical and planar patches. The results confirm the predictions suggested by the theory: (1) Sensitivity to curvature was always greater when the cylinder axis and the frontal translation were parallel than when they were orthogonal. The ratio of curvature detection thresholds in the two cases was between 1.3 and 2.5; the value predicted from the spin variation theory is about 2. (2) Sensitivity to curvature increased strongly with the velocity of the motion but was only weakly affected by its amplitude and the duration of viewing for the range of values used in our experiments.     

Variations on the Ramsey test: More triviality results

The purpose of this note is to formulate some weaker versions of the so called Ramsey test that do not entail the following unacceptable consequenceIf A and C are already accepted in K, then if A, then C is also accepted in K. and to show that these versions still lead to the same triviality result when combined with a preservation criterion.     

Autobiographical memory impairment in chronic schizophrenia: Significance and clinical correlates

Previous studies of autobiographical memory (AM) in schizophrenia yielded a reduction of specificity, richness of details and conscious recollection, which indicate both, quantitative and qualitative AM changes. However, their associations with psychopathological symptoms and neuropsychological deficits were not resolved. Therefore, we sought to investigate AM with respect to psychopathology and neuropsychology in patients with chronic schizophrenia to rule out the influence of different courses of the disease. AM of four lifetime periods was examined in 75 patients and 50 healthy controls by using a semi-structured interview. The recalled episodes were rated for memory specificity. Subsequently, one single event of each period of life was rated for details and experiential aspects of reliving (originality, vividness/visual imagery, emotional re-experiencing and emotional valence). When contrasted with healthy controls, patients recalled a significantly reduced number of episodes and personal semantic facts; moreover, memory specificity of AM was significantly lower in patients than controls. While the richness of details calculated for single events showed only minor, non-significant group differences, vividness and emotional re-experiencing were significantly less pronounced in the patient group. Along with this, AM performance correlated significantly with negative symptoms including apathy as well as verbal memory and executive functions. Our results underline the significance of overgenerality as a key feature of AM in schizophrenia as well as a dissociation between intact number of details of single events and reduced vividness and emotional re-experiencing. The extent of negative symptoms including apathy and impairments of verbal memory/executive functions may explain AM deficits in chronic schizophrenia.     

Self-image,perception of peers' risk acceptance and risky shift

Twelve four-person female groups of subjects displaying the typical underestimation of their peers' (relative to their own) risk acceptance were compared with twelve groups of subjects who (slightly) overestimated their peers' risk acceptance. Risk level was measured by responses to a set of hypothetical decision situations known to elicit risky shift on the basis of previous research. Risky shift following group discussion was not found to be different for the two types of groups, casting doubt on the widely suggested role of peer underestimation in risky shift. Nor was risky shift affected by whether or not group members stated their individual decisions publicly at the close of discussion. Larger group risky shifts were accompanied by higher self-ratings given by group members on a number of polarity scales. In discussing the findings, we outline an explanation of group-induced shifts in risk taking, emphasizing the motivational and informational inducements provided by group discussion whereby group members come to discard their prior positions in favor of more aspired ones.     

Factors limiting the generality of the risky-shift phenomenon

While a considerable amount of research has centered on explaining the risky shift (enhancement of risk acceptance through group discussion; see, for example, Dion, Baron, and Miller, 1970), few studies have investigated the generality of the phenomenon. Three of several ways in which the laboratory context is usually lacking of reality are: (a) The decision consequences are imaginary, as in the ‘Choice-Dilemma’ situations used in most of the risky-shift research; (b) the decision consequences - even if they are real (e.g. money) - are slight; and (c) the decisions are made for oneself (whereas in real life many decisions involve agents acting on behalf of others). The present study was designed to investigate the effects of the above three factors - type of incentive, magnitude of stake and decision target - using a betting task as the decision situation.