“…Barrier crossing is, in fact, an intriguing locomotor behavior, in that it is constrained by a number of variables, ranging from basic biomechanical factors such as (a) balance control (on one or two legs), leg strength, hip flexibility, and so on, (b) anthropomorphic factors, such as overall height, leg length, calf length, general body proportions and weight distribution, and so on, and (c) visual sensitivities, such as 2There does exist developmental research examining the growth of component skills necessary for visually guided locomotion. A partial list of such abilities include spatial orientation (Anooshian & Wilson, 1977;Cohen, Baldwin, & Sherman, 1978;Comell, Heth, & Broda, 1989;Herman, 1980;Kosslyn, Pick, & Fariello, 1974;Rieser, Doxsey, McCarrell, &Brooks, 1982)' detour behavior (Heth & Comell, 1980;Lockman, 1984;Lockman, Greer, & Sisselman, 1992;McKenzie & Bigelow, 1986;Robinson, McKenzie, &Day, 1991), motor control of stepping and walking (Clark & Whitall, 1989;Clark, Whitall, & Philips, 1988;Sutherland, Olshen, Cooper, & Woo, 1980;Thelen, 1984Thelen, , 1986Thelen, Ridley-Johnson, &Fisher, 1983;Thelen, Skala, &Kelso, 1987;Thelen &Ultich, 1991;Whitall &Clark, 1994), perceiving the propertiesof surfaces to be crossed (e.g., E. J. Gibson, Riccio, Schmuckler, Stoffregen, Rosenberg, & Taonnina, 1987), the visual control of posture (Bai, 1991;Bertenthal & Bai, 1989;Butterworth &Hicks, 1977;Delorme, Frigon, &Lagace, 1989;Lee & Aronson, 1974;Schmuckler, in press; and so on.…”