12/13/2023 0 Comments Motion parallax psychologyAt approximately seven months of age, infants under these testing conditions become sensitive to a variety of pictorial cues to depth, as indicated by their reliable reaching for the apparently nearer picture (Yonas and Granrud 1985). A preferential reaching technique was developed by Albert Yonas to determine, under monocular viewing conditions, whether infants perceive the depth information in pictures. These cues include shading, occlusion, and linear perspective (e.g., receding railroad tracks that converge in the picture plane). Pictorial cues to depth are contained in flat (two-dimensional) representations of actual (three-dimensional) scenes. These same processes were earlier demonstrated in the visual cortex of cats and monkeys (see Neural Plasticity in Visual Cortex), and subsequently confirmed behaviorally. Thus, there is a sensitive period during which a normally developing neural mechanism for stereopsis, present by four months of age, can be permanently disabled by subsequent abnormal binocular experience (strabismus). If uncorrected in infancy, this misalignment can result in a permanent loss of the capacity for stereopsis, even if the eyes are surgically realigned in childhood (Banks et al. Some individuals, including some infants, have an ocular misalignment (strabismus) that eliminates fusion and stereopsis. In adults, failure to align both foveas onto a stimulus typically leads to binocular rivalry and prevents stereopsis (the appreciation of depth from retinal disparity). Prior to three months of age, infants appear to have a much greater tolerance for fusing discrepant images than adults, perhaps because of their poor acuity and contrast sensitivity (Birch et al. Binocular rivalry occurs when the discrepant retinal images cannot be fused into a single percept. 1985).ĭuring this same age range, infants become sensitive to binocular rivalry: the perceptual conflict induced by presenting grossly different images to the two retinas (e.g., horizontal stripes in one eye and vertical stripes in the other). Moreover, the smallest retinal disparity that is just discriminable by infants improves very rapidly between three and five months of age, progressing from no sensitivity to nearly adult values (less than one minute of arc) in this age range (Birch et al. FPL and VEP studies have demonstrated that sensitivity to retinal disparity does not emerge until three to four months after birth. Retinal disparity refers to the subtle differences in the images projected to the two retinas from an object at near (less than five meters) viewing distances. Thus, sensitivity to depth from motion is present in very early infancy and does not require the use of both eyes (Kellman and Arterberry 1998). A rapidly approaching (looming) stimulus elicits a blink response in one-month-olds, and motion parallax (more rapid image speed for near than for far objects) enables three-month-olds to discriminate small differences in object distance. The relative distance (depth) of objects can be appreciated using three different sources of information: motion, retinal disparity, and pictorial cues. Aslin, in International Encyclopedia of the Social & Behavioral Sciences, 2001 6 Depth and Binocular Rivalry To this end, we start the discussion of interactivity in visualization with the typical costs associated with getting knowledge, including, eye movements, visual processing, and the time to navigate an information space by means of mouse clicks, walking, or zooming. Ultimately design decisions should stem from the goal of creating visualizations that are efficient cognitive tools. The idea of 2.5D design is introduced as a way of specifically taking the structure of visual space into account, and introducing elements of 3D in a judicious way to enhance a mostly 2D information display. ![]() The picture plane dimensions of visual space are very different from the depth dimension in terms of how information is processed by the brain. In a 3D environment, our viewpoint determines how information is processed by the brain, or if it can be seen at all. ![]() Cognitive task requirements should determine which cues to incorporate in a design. We can, for example, choose to use linear perspective, or not, and we can choose to use stereoscopic viewing, or not. However, depth cues are not an all-or-nothing design choice. Incorporating depth cues can enable us to design visualizations that seem three dimensional. The different kinds of depth cues are described including linear perspective, occlusion, stereoscopic depth and motion parallax. These are the means whereby we process distances away from our view point. ![]() We begin with an introduction to depth cues. Getting the Information: Visual Space and TimeĬolin Ware, in Visual Thinking for Information Design (Second Edition), 2022 Abstract
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