The constancy of object orientation: Compensation for ocular rotation

When a thin horizontal line is displaced, either left or right of straight ahead, or when a vertical line is displaced up or down, systematic changes occur in the binocular disparity associated with the target. In threeexperiments, Ss matched the orientation of displaced targets with a variable comparison line. Estimates of apparent displacement with a pointing technique were also made. Since head position was fixed, apparent displacement was mediated by the angle of ocular rotation. Near perfect matches were made with vertical targets, but horizontal targets produced errors suggestive of underestimation of apparent displacement. However, the pointing data did not yield clear evidence for this view. Control data denien the possible role of the induced effect (IE) in matching the horizontal targets, and the result were discussed in the context of orientation constancy based upon compensation for displacement.     

A perceptual-confusion account of the WSE in the target search paradigm

Subjects were required to search through four-letter displays for one member from the target set M, N, P, or R. The displays were words, pseudowords, or consonant strings. The results show that significant word superiority effects occur when target location is unknown, but that a location precue can eliminate these benefits of lexical context. Analysis of the types of errors that occur with and without a location precue indicates that the precue reduces the likelihood that the context letters of nonwords will be confused with the incorrect targets. These findings are consistent with a perceptual-confusion model that predicts that the context letters of words will be perceived more accurately than those of nonwords.     

Do small visual angles produce a word superiority effect or differential lateral masking?

Purcell, Stanovich, and Spector 119781 report that recognition of the center letter of the words APE, ARE, ACE, and AGE is superior to recognition of the same targets in the nonwords formed by the context letters V_H. Since a small set of predesignated targets was used and there was complete certainty about the location of the target letter, these results pose serious problems for three otherwise viable accounts for why word superiority effects (WSEs) are obtained in a variety of other paradigms. This series of experiments explores the possibility that the word advantages reported by Purcell et al. have nothing to do with the lexical properties of the A_E display or the general phenomenon of word superiority, but they result from a fortuitous case of differential lateral masking. This reinterpretation is supported by five experiments. Experiments 1 and 2 show that the A_E word advantages are anomalous in that the magnitude of the WSE obtained with these particular words is not contingent upon the presence of a patterned mask. Experiment 3 provides direct evidence for differential lateral masking by showing that digit recognition is poorer in the V_H than in the A_E frame. Experiments 4 and 5 show that the WSE obtained under these conditions does not generalize to a new set of words and nonwords that produce the same amount of lateral masking. It was concluded that a genuine WSE does not occur under the conditions tested by Purcell et al., and that, therefore, the WSE has not been shown to depend on visual angle.     

Further evidence for an orientation constancy based upon registration of ocular position

Summary In four experiments Ss were exposed to wedge prisms or maintained an asymmetrical eye and head posture in order to induce a shift in the apparent direction of gaze. Systematic changes in the apparent orientation of a line target were obtained as inferred from an assumed algorithm relating optical input and registered direction of gaze.This research was supported by Grant MH13006 from the National Institute of Mental Health to the first author.The aid of Ms. Janine Pyrek and Ms. Lynne Shebilske is gratefully acknowledged.