Local and global mechanisms of one- and two-dimensional orientation illusions.

One-dimensional (1-D) orientation illusions induced on a test grating by a tilted and surrounding 1-D inducing grating have a well-known angular function that exhibits both repulsion and attraction effects. Two-dimensional (2-D) orientation illusions are those induced on a test grating by 2-D image modulation, such as a pair of superimposed inducing gratings at different orientations, usually orthogonal (a plaid). Given the known angular functions induced by the plaid component gratings, two hypotheses were developed that predicted different plaid-induced illusion functions. Hypothesis 1 states that the 1-D component-induced effects simply add linearly; Hypothesis 2 states that there is an additional mechanism that responds to the virtual axes of mirror symmetry of the plaid and adds to the effect. The data of two experiments were consistent with the predictions from the second hypothesis but not the first. Possible neural substrates of mechanisms that extract axes of symmetry are discussed; it is suggested that such global symmetry axes may underlie the perceived orientation of complex shapes.     

Analysis of the components of disparity in Wilde's dot-row phenomenon

Summary In this study on Wilde's phenomenon (Wilde 1950) the two components of disparity, one of them processing displacement, and the other one apparent rotation, are analysed in terms of dependence on the disparity of the end-lines of the pattern (), and on the percentage of magnification (M) of one of the monocular patterns in relation to the other one. It was found that the component of disparity for displacement ' can be expressed as a linear regression equation '=–a+b.The component of disparity for rotation, expressed as a percentage of magnification effective for rotation (M) can be expressed as M=a–b₁+b₂M.It was concluded that the two components of disparity are processed through independent parallel channels, the processing of the component of disparity for displacement being the faster process, accounting for the larger part of the total disparity.     

Maximum likelihood estimation for Luce's choice model

A terminology for general choice models based on the choice axiom is given. It applies to all kinds of choice experiments, such as confusion choice experiments, paired comparisons, triadic comparisons, directional rankings, scores on binary test items, and others. Maximum likelihood estimation for such general choice models is considered. Conditions for the uniqueness of maximum likelihood estimates are given, and it is shown that the estimates can be derived by iterative proportional fitting. This offers the opportunity of a general test of the choice axiom for all kinds of choice experiments using the likelihood ratio. The estimation and testing procedure is applied to data from a form recognition experiment, reported by W. A. Wagenaar (Nederlands Tijdschrift voor de Psychologie, 1968, 23, 96–108).     

Fantasy as a medium for the reduction of trait versus state aggression

In the first phase of an experiment reducing hostility through fantasy, 203 first and second-year high school students completed a daydreaming scale, Rotter ISB, and a sociometric scale designed to ascertain which of their peers behave aggressively. The students of the upper and lower quarters of the daydreaming scale were classified as high and low fantasy, and as aggressive or nonaggressive subjects. The second phase, two weeks later, consisted of 94 subjects forming three groups: a trait aggressive group, a nonaggressive control group, and a group of nonaggressive subjects experimentally manipulated for aggression. Half of the subjects composed stories to four high-cue aggressive TAT cards; the other half read neutral stories. All the subjects then again completed the Rotter ISB which was scored for aggression. Analysis of covariance of the scores indicated that a reduction in hostility occurred only for the group experimentally aroused to aggression in the TAT condition. The scores of the trait-aggressive subjects, tested in a before-after analysis, showed an increase in their hostility level. Fantasy capacity did not influence the scores.     

The Role of Social Skills in Predicting Treatment-Recovery in Children with a Social Anxiety Disorder

Research on Child and Adolescent Psychopathology - The current study investigated the role of social skills and its interaction with social anxiety as predictors of treatment outcome in children...