The development of haptic processing skills from childhood to adulthood by means of two-dimensional materials.

Research into haptic perception has mostly focused on 3-dimensional objects, and more needs to be known about the processing of 2-dimensional materials (e.g., raised dots and lines and raised-line shapes, patterns and pictures). This study examines the age-related changes in various skills related to the haptic exploration of 2-dimensional raised-line and dot materials and how these skills are related to haptic picture perception. Ninety-one participants, aged 4 years to adult, were asked to perform a series of haptic tasks that entailed (a) finding dots and following lines; (b) matching elements based on texture, shape, and size; (c) matching elements based on spatial location and orientation; (d) memorising sequences of dots and shapes; and (e) identifying complete and incomplete raised-line pictures. On all the tests, the results showed that scores improved with age. Shape discrimination scores accounted for variability in comprehension scores for outline pictures. We suggested that identifying tactile pictures by touch improved with age and mainly depended on the improvement of shape discrimination skills.