Gobal-local precedence in picture processing

Summary Previous investigations of the global precedence hypothesis (Navon, 1977) have utilized compound letter stimuli. In these stimuli there is no predictive relationship between the global and local levels. Pictorial stimuli, however, contain mutually predictable global and local levels. This study investigated the global precedence hypothesis with pictorial stimuli using a Stroop-like interference task similar to that used by Navon. Subjects were required to respond either to the global (e.g., beach or farm) or local (e.g., boat or tractor) level of a scene. The display size and consistency of the global and local levels were varied. Response latencies supported global precedence for small scenes (4°) but local precedence for large scenes (16°). The results are interpreted by a model in which the priority of processing is determined by a critical spatial frequency sampling bandwidth.Portions of this research were presented at the meeting of the Psychonomic Society, Minneapolis, November, 1982. The authors with to express their sincere appreciation to Tom Petros for his assistance in data analysis. Requests for reprints should be addressed to James R. Antes, Department of Psychology, University of North Dakota, Grand Forks, ND 58202.     

Cognitive dysfunction in compulsive checkers: Further explorations

Recent evidence suggests a relationship between certain memory deficits and compulsive-checking behavior. The present study explores this relationship in the context of several additional memory capacities not yet investigated. Using the Maudsley Obsessional-Compulsive Inventory and the Everyday Checking Behavior Scale four groups of Ss were identified: (1) frequent checkers, (2) occasional checkers, (3) infrequent checkers and (4) noncheckers. Consistent with previous research, a memory-for-actions task indicated a deficit among compulsive checkers. Furthermore, checking status was found to be negatively related to memory functioning as measured by the Wechsler Memory Scale (WMS) and the Cognitive Failures Questionnaire (CFQ). This memory deficit was most pronounced on the Logical Memory subtest of the WMS. Checkers appear to have difficulty recalling details of meaningfully linked sequences, either presented in narrative form or engaged in personally. Although the reasons for these checking-related deficits are not clear, a complete understanding of checking phenomena will involve an appreciation of the role played by memory deficits.     

Agreement between observers when the categories are not specified in advance

To test the agreement between two observers who categorize a number of objects when the categories have not been specified in advance, Brennan & Light (1974) developed a statistic A′ and suggested a normal approximation for its distribution. In this paper it is shown that this approximation is inadequate particularly when one, or both, of the observers place a fairly equal number of objects in all of their categories. A chi-squared approximation to the distribution of A′ is developed and is shown to work well in a variety of situations. The relative powers of A′ and the ordinary X² test for association are dependent on the type of ‘agreement between the observers’ that is assumed. However a simulation for a fairly general type of agreement indicates that the X² test is more powerful. As the X² test is also much easier to apply, it would seem preferable in most situations.     

Variation of the magnitude of the horizontal-vertical illusion with retinal eccentricity

The horizontal-vertical illusion was studied as a function of retinal eccentricity. It was found that the relation of illusion magnitude to vertical eccentricity is described by a U-shaped function with large amounts of reversed illusion for the more eccentric positions. Substantial effects due to horizontal eccentricity were also obtained, but these were not consistent across subjects. It is suggested that the flattening of the peripheral zones of the refracting surfaces of the eye may be involved in the variation of the illusion with retinal position, and that the astigmatic properties of the central portions of these surfaces may be a prime factor in the usual horizontal-vertical illusion.