Detection of invariants by haptic touch across age groups: Rod length perception

This study examined the development in the detection of maximum eigenvalues and static moment as invariants, through a task of perceiving rod length without visual information by haptic touch. 34 participants ages 6 to 83 years participated in the experiment. Their exploratory behavior and perceptions of rod length were analyzed by age group (Children: 6 to 12 years old; Young Adult: 21 to 25 years old; Middle Age: 31 to 56 years old; and Older: 65 to 83 years old). A behavior analysis indicated that use of vertical swinging increased for the Young Adult group and decreased with age for the Older group, whereas Children frequently held the rod without wielding. Analysis showed that, by age, differences in coefficients on the maximum eigenvalue and static moment were parallel with an exploratory behavioral change. Finally, the effect of different exploratory behaviors on length perception was discussed.