A novel eye-tracking task to assess mental rotation from infancy to early childhood

Mental rotation, or the ability to rotate a visual representation of an object, is important for object recognition (Biederman and Gerhardstein, 1993). Although mental rotation has been studied in infants, less is known about its development from infancy to childhood. We examined developmental changes in mental rotation from 12 to 36 months using a novel gaze-contingent staircase procedure. We tested 12- (n = 18), 24- (n = 18), and 36-month-old children (n = 11) in a two-up one-down eye-tracking staircase procedure. On each trial, children saw a giraffe ranging from 0˚ (fully upright) to 180˚ (fully inverted) in the middle of the screen, and houses to the left and right. Children were trained with the giraffe at 0˚. During test trials, we recorded children’s fixations to determine whether they correctly anticipated where the giraffe would travel; correct looks were rewarded with a short animation. Evaluation of the highest successful angle of rotation for each age group suggested developmental improvement; on average, the highest level of rotation the 12-month-old children succeeded at was between 15˚ and 30˚ rotation, 24-month-old children succeeded at 30˚, and 36-month-old children succeeded at 45˚. This developmental trajectory was confirmed with hazard ratios (HR) derived from proportional hazards regression analysis (HR < 1 indicates increased likelihood of surviving through the staircase, HR > 1 indicates decreased likelihood of survival). Thirty-six-month-old children progressed significantly further through the staircase than 12-month-old children, HR = 0.20, p < .001, and 24-month-old children, HR = 0.32, p = .006. Twelve- and twenty-four-month-old children were not significantly different from each other. Using a novel eye-tracking staircase procedure, we showed development in mental rotation from 12 to 36 months of age. This is the first task to show developmental change in this aspect of view-invariant visual object recognition across this age range.