Academic journal article Perception and Psychophysics

Aging and the Perception of Slant from Optical Texture, Motion Parallax, and Binocular Disparity

Academic journal article Perception and Psychophysics

Aging and the Perception of Slant from Optical Texture, Motion Parallax, and Binocular Disparity

Article excerpt

The ability of younger and older observers to perceive surface slant was investigated in four experiments. The surfaces possessed slants of 20°, 35°, 50°, and 65°, relative to the frontoparallel plane. The observers judged the slants using either a palm board (Experiments 1, 3, and 4) or magnitude estimation (Experiment 2). In Experiments 1-3, physically slanted surfaces were used (the surfaces possessed marble, granite, pebble, and circle textures), whereas computer-generated 3-D surfaces (defined by motion parallax and binocular disparity) were utilized in Experiment 4. The results showed that the younger and older observers' performance was essentially identical with regard to accuracy. The younger and older age groups, however, differed in terms of precision in Experiments 1 and 2: The judgments of the older observers were more variable across repeated trials. When taken as a whole, the results demonstrate that older observers (at least through the age of 83 years) can effectively extract information about slant in depth from optical patterns containing texture, motion parallax, or binocular disparity.

Over the past 200 years, researchers have thoroughly investigated the various sources of optical information that support the human perception of 3-D object shape. Any list of these sources would certainly include binocular disparity (e.g., Julesz, 1960, 1964, 1971; Wheatstone, 1838), motion parallax (e.g., Helmholtz, 1866/1925; Norman, Clayton, Shular, & Thompson, 2004; Ono & Wade, 2005; Rogers & Graham, 1979, 1982), shading (e.g., Bülthoff & Mallot, 1988; Todd, 1985; Todd & Reichel, 1989), specular highlights (e.g., Norman, Todd, & Phillips, 1995; Todd, Norman, Koenderink, & Kappers, 1997), and gradients of optical texture (e.g., Andersen, Braunstein, & Saidpour, 1998; Gibson, 1950a, 1950b; Newman, Whinham, & MacRae, 1973; Rosas, Wichmann, & Wagemans, 2004; Saunders, 2003; Todd & Akerstrom, 1987; Todd, Thaler, & Dijkstra, 2005). Although aging has been a subject of psychological interest for almost 100 years (e.g., Hall, 1922), little research on aging and the perception of 3-D object shape was conducted until about a decade ago.

In the past 10-15 years, psychologists have begun to evaluate older observers' ability to perceive various aspects of 3-D object shape from binocular disparity (Norman, Crabtree, Herrmann, et al., 2006; Norman, Dawson, & Butler, 2000), motion (Andersen & Atchley, 1995; Norman et al., 2004; Norman, Dawson, & Butler, 2000), shading (Norman, Crabtree, Norman, et al., 2006; Norman & Wiese mann, 2007), and specular highlights (Norman, Crabtree, Norman, et al., 2006; Norman & Wiesemann, 2007). All of these studies have shown significant negative effects of increasing age on the perception of 3-D shape. The age differences, however, have largely been quantitative; the qualitative patterns of older observers' perceptual judgments are typically similar to those exhibited by younger observers. Some of the largest age effects have involved the perception and discrimination of 3-D shape from motion (see, e.g., Norman et al., 2004; Norman, Dawson, & Butler, 2000). This is perhaps not surprising, because other research has consistently shown that older observers' ability to detect and discriminate motion itself is reduced, relative to that of younger observers (see Habak & Faubert, 2000; Norman, Ross, Hawkes, & Long, 2003; Snowden & Kavanagh, 2006). Likewise, 30 years of research have clearly demonstrated that older observers exhibit difficulty in detecting intermediate and high spatial frequencies (see, e.g., Arundale, 1978; Bennett, Sekuler, & Ozin, 1999; Elliott, Whitaker, & MacVeigh, 1990; Kline, Schieber, Abusamra, & Coyne, 1983; McGrath & Morrison, 1981; Morrison & Reilly, 1986; Owsley, Sekuler, & Siemsen, 1983). Given this age-related reduction in the ability to detect higher spatial frequencies, one might expect that older observers would face a similar difficulty in extracting the spatial information embedded in texture gradients. …

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