Effects of changes in size, speed, and distance on the perception of curved 3-D trajectories

Previous research on the perception of 3-D object motion has considered time to collision, time to passage, collision detection, and judgments of speed and direction of motion but has not directly studied the perception of the overall shape of the motion path. We examined the perception of the magnitude of curvature and sign of curvature of the motion path for objects moving at eye level in a horizontal plane parallel to the line of sight. We considered two sources of information for the perception of motion trajectories: changes in angular size and changes in angular speed. Three experiments examined judgments of relative curvature for objects moving at different distances. At the closest distance studied, accuracy was high with size information alone but near chance with speed information alone. At the greatest distance, accuracy with size information alone decreased sharply, but accuracy for displays with both size and speed information remained high. We found similar results in two experiments with judgments of sign of curvature. Accuracy was higher for displays with both size and speed information than with size information alone, even when the speed information was based on parallel projections and was not informative about sign of curvature. For both magnitude of curvature and sign of curvature judgments, information indicating that the trajectory was curved increased accuracy, even when this information was not directly relevant to the required judgment.     

Psychobiological Roots of Early Attachment

ABSTRACT— New laboratory research has revealed a network of simple behavioral, physiological, and neural processes that underlie the psychological constructs of attachment theory. It has become apparent that the unique features of early infant attachment reflect certain unique features of early infant sensory and motor integration, learning, communication, and motivation, as well as the regulation of biobehavioral systems by the mother–infant interaction. In this article, I will use this new knowledge to answer three major questions that have remained unsettled in our understanding of early human attachment: What creates an attachment bond? Why is early maternal separation stressful? How can early relationships have lasting effects? I will discuss the implications of these new answers for human infants and for the development of mental processes. Attachment remains useful as a concept that, like hunger, describes the operation of subprocesses that work together within the frame of a vital biological function.     

The game of “it”

Pastoral Psychology -     

The impact of family functioning on family racial socialization processes

This longitudinal study evaluated the relationship between family functioning and family racial socialization processes in a clinical sample of African American youth referred for drug abuse treatment. Participants were 77 African American adolescents and their parents. Results showed that participants assigned to structural ecosystems therapy experienced a greater increase in family racial socialization processes during treatment than participants assigned to the treatment as usual in community settings condition. Participants in structural ecosystems therapy also demonstrated a greater increase in family functioning than participants in community settings condition, and this improvement in family functioning mediated the relationship between treatment condition and family racial socialization processes. Research and clinical implications are discussed.     

Predominance of ground over ceiling surfaces in binocular rivalry

The superiority of ground surfaces over ceiling surfaces in determining the representation of the visual world, demonstrated in several studies of visual perception and visual search, has been attributed to a preference for top-away projections resulting from ecological constraints. Recent research on binocular rivalry indicates that ecological constraints affect predominance relations. The present study considered whether there is a difference in predominance between ground and ceiling surfaces. In Experiment 1, we examined whether a ground surface would dominate a ceiling surface when one surface was presented to each eye. In Experiment 2, we used an eye-swapping paradigm to determine whether a ground surface would come to dominance faster than a ceiling surface when presented to the suppressed eye. The eye-swapping paradigm was used again in Experiment 3, but the ground and ceiling planes were replaced with frontal planes with similar variations in texture density. The results of these experiments indicate that ground surfaces are predominant over ceiling surfaces, with this predominance affecting both the dominance and suppression phases of binocular rivalry. This superiority of ground planes is independent of image properties such as the increase or decrease in texture density from the lower half to the upper half of the images.     

Discriminating direction of motion trajectories from angular speed and background information

The effects of a background scene on the perception of the trajectory of an approaching object and its relation to changes in angular speed and angular size were examined in five experiments. Observers judged the direction (upward or downward) of two sequentially presented motion trajectories simulating a sphere traveling toward the observer at a constant 3-D speed from a fixed distance. In Experiments 1–4, we examined the effects of changes in angular speed and the presence of a scene background, with changes in angular size based either on the trajectories being discriminated or on an intermediate trajectory. In Experiment 5, we examined the effects of changes in angular speed and scene background, with angular size either constant or consistent with an intermediate 3-D trajectory. Overall, we found that (1) observers were able to judge the direction of object motion trajectories from angular speed changes; (2) observers were more accurate with a 3-D scene background, as compared with a uniform background, suggesting that scene information is important for recovering object motion trajectories; and (3) observers were more accurate in judging motion trajectories based on angular speed when the angular size function was consistent with motion in depth than when the angular size was constant.     

Incommensurability, incomparability, and rational world-choice

Klaas J. Kraay argues that the rational choice model for divine creation—according to which God chooses to actualize one world among possible alternatives based on its axiological properties—cannot succeed given failures of comparability across possible worlds. I argue that failure of comparability across worlds would not undermine the rationality of choosing one world to create among possible alternatives.