The relationship between perceived length and egocentric location in Müller-Lyer figures with one versus two chevrons

We examined the apparent dissociation of perceived length and perceived position with respect to the Müller-Lyer (M-L) illusion. With the traditional (two-chevron) figure, participants made accurate open-loop pointing responses at the endpoints of the shaft, despite the presence of a strong length illusion. This apparently non-Euclidean outcome replicated that of Mack, Heuer, Villardi, and Chambers (1985) and Gillam and Chambers (1985) and contradicts any theory of the M-L illusion in which mislocalization of shaft endpoints plays a role. However, when one of the chevrons was removed, a constant pointing error occurred in the predicted direction, as well as a strong length illusion. Thus, with one-chevron stimuli, perceived length and location were no longer completely dissociated. We speculated that the presence of two opposing chevrons suppresses the mislocalizing effects of a single chevron, especially for figures with relatively short shafts.     

The Infallibility of the Ordinary Universal Magisterium: A Critique of Some Recent Observations

This teaching of Vatican II raises the problem of how to know when the ordinary universal magisterium has proposed some doctrine as definitive. Fr. Francis A. Sullivan has put forth some principles that he claims are important for establishing that a doctrine has been definitively taught. Key to Sullivan's principles is the claim that the constant consensus of theologians is a sign and a necessary condition for establishing whether the ordinary universal magisterium has taught a particular doctrine as definitive. This essay argues against this claim. It maintains that while the consensus of theologians may be sign of definitive teachings, it is not a necessary condition for those teachings. Lastly, the essay suggests that the current discussion about the definitive, infallible teachings of the ordinary universal magisterium would be greatly aided if it took place in the context of the quest for catholicity in time and if it firmly kept in mind the nature of church as a communion.     

Dual adaptation and adaptive generalization of the human vestibulo-ocular reflex

In two experiments, we examined the possibility that the human vestibulo-ocular reflex (VOR) is subject todual adaptation (the ability to adapt to a sensory rearrangement more rapidly and/or more completely after repeated experience with it) andadaptive generalization (the ability to adapt more readily to a novel sensory rearrangement as a result of prior dual adaptation training). In Experiment 1, the subjects actively turned the head during alternating exposure to a visual-vestibular rearrangement (target/head gain=0.5) and the normal situation (target/head gain=0.0). These conditions produced both adaptation and dual adaptation of the VOR but no evidence of adaptive generalization when tested with a target/head gain of 1.0. Experiment 2, in which exposure to the 0.5 gain entailed externally controlled (i.e., passive) whole body rotation, resulted in VOR adaptation but no dual adaptation. As in Experiment 1, no evidence of adaptive generalization was found.     

Generalization gradients following differential intradimensional autoshaping.

Three pigeons were trained on a differential, intradimensional autoshaped discrimination. A 45 degrees line tilt was always paired with food whereas a 15 degrees line tilt was never paired with food. All subjects learned the discrimination within 17 sessions. The pigeons were then given generalization tests in extinction over seven line tilts (0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees and 90 degrees). The subjects yielded generalization gradients with maxima at 45 degrees and minima at 15 degrees. An area shift, but no peak shift, was found for each subject.     

Employment and health among married women with children

A sample of nearly 500 urban married women with children was used to evaluate the possible effect of outside-the-home employment on the mental and physical health of married mothers. Six measures of health were used, some drawn from interviews with the women, others from a medical examination. After controlling for ethnicity, education, and age of the women, the husband's occupation, number of children in the family, and length of time the woman has been married, it was found that wives who had been employed for more than a year were healthier than wives not employed outside the home and wives who had worked less than one year. Housewives who had never worked outside the home were healthier, on the whole, than wives who had been employed at some time in the past. Poor marital relationships and having no preschool age children seemed to increase the health advantage of long-term employed wives over those in the housewife categories. The occupational status of wife and husband did not seem to change these health differences very much.An earlier version of this paper was presented at the annual meeting of the Southwest Social Science Association, San Antonio, March 1975. The authors would like to thank Donna Duvall, Ministry of State for Urban Affairs, Ottawa; Elaine Hess, University of Nebraska at Omaha; and David R. Johnson, University of Nebraska — Lincoln for their comments. Gilles Robert and Marie Josepha Hebert ably assisted with various aspects of this project. Support for the project was provided by the Ministry of State for Urban Affairs, but the views expressed here are those of the authors and not necessarily those of the Ministry.     

The absence of depth constancy in contour stereograms

Stereoscopic surfaces constructed from Kanizsa-type illusory contours or explicit luminance contours were tested for three-dimensional (3-D) shape constancy. The curvature of the contours and the apparent viewing distance between the surface and the observer were manipulated. Observers judged which of two surfaces appeared more curved. Experiment 1 allowed eye movements and revealed a bias in 3-D shape judgment with changes in apparent viewing distance, such that surfaces presented far from the observer appeared less curved than surfaces presented close to the observer. The lack of depth constancy was approximately the same for illusory-contour surfaces and for explicit-contour surfaces. Experiment 2 showed that depth constancy for explicit-contour surfaces improved slightly when fixation was required and eye movements were restricted. These experiments suggest that curvature in depth is misperceived, and that illusory-contour surfaces are particularly sensitive to this distortion.