Haptic two-dimensional shape identification in children, adolescents, and young adults

We investigated the influence of image mediation (the process that translates tactile information into a visual image) on the development of haptic two-dimensional (2D) shape identification in 78 participants from five different age groups: preschoolers (4-5 years), first graders (6-7 years), fifth graders (10-11 years), young adolescents (12-13 years), and young adults (18-28 years). Participants attempted to haptically recognize everyday objects (three-dimensional [3D] haptic condition) and tangible line drawings (2D haptic condition) and to recognize objects presented through a serial visual "peek hole" version of the haptic line drawing task (2D visual condition). All groups were excellent at 3D haptic identification. However, preschoolers and first graders scored low in both visual and haptic line drawing tasks. From fifth grade onward, participants were reliably better at the visual peek hole task compared with the haptic line drawing task, which improved only gradually in young adolescent and adult age groups. We argue that both the spatial reference frame and working memory capacity constrain image mediation and children's increasing abilities to correctly haptically identify 2D shapes.