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.     

The linguistic organization of public controversy: A note on the pragmatics of political discourse

Conclusion This paper does not mean to imply that it is only public controversy that can meaningfully affect political outcomes, or even that it is the most important factor. Rather, we have attempted to indicate that public controversy constitutes a forum on which political actorsact; on which they attempt to implicate each other and the public in terms of some preferred view of the controversy at hand. It is certainly the case that the formal structure of the government and power relationships provides important constraints in terms of which controversy may take place. Yet within these constraints, actors can meaningfully construct various views of the structure of the controversy which differently construe the rights and obligations of participants. In this sense, the course of public controversy may in part be understood as a function of the language employed by these actors, both to the extent that particular expressions stand as documentary evidence of underlying discrepancies about the shape of the controversy and to the extent that the logic of certain speech-acts constrains the forms subsequent statements may take.     

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).     

Patterns of interocular transfer of visuomotor coordination reveal differences in the representation of visual space

Acquisition and interocular transfer of adaptation to optical transformations of input were examined in strabismic and orthotropic subjects. Distinct patterns of behavior were displayed by three groups: strabismic alternating suppressors, strabismic and orthotropic constant suppressors, and orthotropes with normal binocularity of vision. It is suggested that these behaviors result from the way in which visual space is represented in each group, an outcome of the pattern of use of the eyes during early development. The conditions for modification of the representation of visual space appear to parallel those for initial acquisition.