Modelling visual detection: Luminance response non-linearity and internal noise

Two experiments that investigate the effect of various display factors on the detectability of a thin line signal in random visual noise are described. Three statistical decision models are described, together with their ability to account for the results. The first is an “ideal detector” model, the second an “energy integrator” model, and the third a model based upon the operation of retinal ganglion cells which incorporates a gain control mechanism. The ideal detector model fails to give a good account of human performance, whereas the other two models provide a good fit to the data. The digital Laplacian with gain control model has the slight advantage over the energy integrating model in being able to account for a small superiority in the detection of dark as opposed to bright signals. Finally, both models require the inclusion of an estimate of the internal noise of the human visual system to account for the pattern of performance observed under changing conditions of display contrast.     

Stuffed Cabbage in the Old New School Cafeteria

The purpose of this lecture is to celebrate the memory of Aron Gurwitsch by examining and enlarging the domain of phenomenological clarification of some elements of what Gurwitsch called the logic of reality. Chief among those elements are the nature of the taken-for-grantedness of our existential belief, the difference between presentive and non-presentive indices of reality and the ground for the self-illumination of the world of working.     

Sex differences in symbol-digit substitution task performance

Estes (1974) proposed that the superior performance of women over men on the Digit-Symbol Substitution subtest of the Wechsler scales was due to their greater ability to encode symbols verbally. Three forms of a symbol-digit substitution task were administered to 62 female and 96 male college students. The symbol sets of the three forms differed in the relative amount of figural and spatial orientational information. Women performed better than men on the form which used the Wechsler symbol set in which all symbols are figurally different and, presumably, most easily coded verbally. Men performed better than women on the form which had the greatest amount of spatial orientational information. Estes' hypothesis is supported by these findings.     

Similarities and differences in social attitudes in four Western countries1

A referents scale (single words and short phrases) constructed to measure social attitudes and values was administered to 500 graduate students of education in the United States, 427 mature evening students in Spain, 130 German students, 270 Dutch students, and 685 Dutch adults, a random sample of the Netherlands. The attitudes of the samples were compared by analysis of the means of clusters of referents associated with the factors common to all samples. The means of selected individual referents of social significance were similarly compared across samples. In general, the U.S. student sample and the Netherlands random sample were more conservative than the Spanish, Dutch, and German student samples. On the other hand, the Dutch, Spanish, and American students were more liberal than the Dutch random sample and the German students. The correlations between the profiles of means of referents common to pairs of samples were mostly substantial (average r's of .75 for conservative referents and .62 for liberal referents), indicating considerable cross-cultural agreement in the rank ordering of the referents within the conservative and within the liberal categories, and thus, presumably, common cores of reaction to the two kinds of referents. The use of attitude-value referents, especially in cross-cultural research, was judged valid and useful.     

Linking empirically based theory and evaluation: The family bereavement program

Conclusion We have illustrated how our small theory (Lipsey, 1990) of bereavement guided the development and evaluation of a preventive intervention for bereaved children. Our small theory, based on prior empirical research, enabled us to identify family processes that appeared to mediate the effects of parental death on child mental health. Our intervention was designed to attempt to change these processes. The evaluation of our experimental trial of the intervention assessed changes on these processes as well as the more distal mental health outcomes. The experimental trial showed some-what encouraging results, in terms of the program's ability to modify the warmth of the parent–child relationship and to decrease symptomatology in the adolescent children. We also obtained further empirical support for our underlying theoretical model. Finally, implications for redesign of the program were derived from assessing the adequacy of the program components to change each of the mediators in the theoretical model.Support for this research was provided by NIMH grant P5OMH39246 which is gratefully acknowledged. David R. Pillow is now at Western Psychiatric Institute, Pittsburgh; Fred Rogosch is at the University of Rochester; Janette Beals is now at University of Colorado Health Sciences Center; Kim D. Reynolds is now at the University of Alabama, Birmingham; Carl Kallgren is now at the Pennsylvania State University, at Erie; and Rafael Ramirez is now at the University of Puerto Rico.