Abstract
Mental rotation refers to the process of rotating the image of an object to determine if it is identical to another object presented at a different orientation (Shepard & Metzler, 1971). This ability is thought to involve regions of the cortical visual system involved in processing real motion (e.g. Zacks, 2008). Because children born preterm often show damage to these regions (e.g. Back et al., 2001) and compromised motion processing (MacKay et al., 2005; Taylor et al., submitted), we predicted that they would experience more difficulty than full-term controls with mental rotation. We assessed mental rotation ability (using identical and mirror-image objects) in 15, 5–9 year-old children born at [[lt]]32 weeks gestation, and in 16 full-term controls. The two groups were matched in age and SES and had a similar gender distribution. We observed a classic mental rotation function; thus, matching accuracy decreased as the angular disparity between stimuli increased (F = 13.3, p [[lt]].001). Both groups showed a similar function, suggesting that preterm children can mentally rotate unfamiliar figures in the picture plane (although, as response time data were not collected, it is not clear if they are as efficient as controls in this regard). Despite showing a typical mental rotation function, preterm children performed more poorly than their full-term counterparts overall (F = 10.6, p [[lt]].001), even on trials involving the 0° disparity, mirror-normal discrimination (t = 2.1, p [[lt]]0.05). This suggests that preterm children may have a relative deficit in their ability to mentally transform objects out of the picture plane, a skill thought to be required to make accurate mirror-normal discriminations (cf. Hamm et al., 2004). This finding is consistent with other evidence suggesting the dissociability of (planar) mental rotation and mirror-normal discrimination ability (e.g. Davidoff & Warrington, 2001; Lawson et al., 2000).
This research was supported by a Manitoba Health Research Council Studentship to NT and by a grant from the Natural Sciences and Engineering Research Council to LJ.