Mental Rotation Ability of Individuals with Visual Impairments

The term mental rotation refers to a mental process during which individuals "encode the spatial information into an image, rotate the image mentally, and then access the image in its new orientation" (Warren, 1994, pp. 107-108). Spatial perspective taking is based on a mental rotation process of the self. In spatial perspective taking, individuals seem to rotate themselves mentally into others' orientation to adopt their spatial perspective (Kessler & Thomson, 2010). The mental representation of space is essentially visual (Huttenlocher & Presson, 1973), and some of its aspects, such as perspective, are considered to be visually acquired (Arditi, Holtzman, & Kosslyn, 1988). However, there is another point of view according to which mental representation, even perspective (Heller et al., 2002), neither results from nor reflects visual perception (Millar, 1976). Paivio (1986) suggested that imagery can result from every sensory modality. Some studies have underlined the force of touch in specific tasks, by which individuals with visual impairments performed as well as or even better than their sighted counterparts (Heller, 1989; Heller, Brackett, Scroggs, & Allen, 2001; Noordzij, Zuidhoek, & Postma, 2007). Various studies have been conducted to evaluate mental rotation (Carpenter & Eisenberg, 1978; Dulin & Hatwell, 2006; Marmor & Zaback, 1976) and perspective taking (Millar, 1976) in individuals with visual impairments. The results suggested that visual imagery facilitates the performance of a mental rotation task (rotation of either an object or of the self). The aims of the study presented here were to examine the mental rotation ability of individuals with visual impairments and the effect of visual status, gender, and chronological age on this ability. For this purpose, two tests were conducted--the clock test and the room test. The first test was in essence a perspective task (Huttenlocher & Presson, 1973), and the second test was a mental manipulation task (Penrod & Petrosko, 2003). However, because both tests require conceptually difficult mental rotations (Millar, 1976), we refer to them both as mental rotation tests. METHOD Participants In our study, we followed the ethical principles of the Declaration of Helsinki. In addition, we obtained consent from the participants using the appropriate forms and according to the procedure suggested by the World Medical Association. Twenty-eight individuals with congenital visual impairments were selected, 15 boys and 13 girls, aged 6 years, 8 months, to 18 years (M = 12.37). The sample was randomly selected, and none of the participants had additional disabilities. Of the 28, 14 participants, aged 6 years, 8 months, to 17 years, were totally blind (from birth or prior to age 3) or had only light perception (M = 11.90), and 14 participants aged 8 years, 6 months, to 18 years, had residual vision (M = 12.85). The visual acuity of the participants with residual vision was better than 20/400 and worse than 20/200, and their central functional visual fields were better than 20 degrees (binocularly), examined through a confrontation method using a pen light. [FIGURE 1 OMITTED] Materials and design Three white cardboard squares measuring 25 x 25 centimeters (or about 10 x 10 inches) were used in the first test. In the center of the first square, a fixed, constant indicator made of black sandpaper was placed in a similar direction to that of a clock hand pointing to number 6 (see Figure 1, section a). Similarly, in the center of the second square, there was a fixed, constant indicator that pointed toward the clock position between numbers 7 and 8 (see Figure 1, section b) (hereafter position 6 and position 7.5). In the center of the third square there was an indicator that was fixed with a metal nail in such a way that it could be turned (see Figure 1, section c). …