Haptic Parallelity Matching in Children and Adults

Research in adults has shown that performance is not veridical when participants have to set two bars parallel to each other haptically. It is hypothesized that this is due to the influence of the egocentric reference frame. In addition, larger deviations have been observed for oblique orientations compared to cardinal orientations and for female participants compared to male participants. So far, haptic parallelity performance in children has not been studied in detail. To close this gap the current study compared parallelity matching in children and adults, to address the question if the influence of the egocentric reference frame is the same in children and adults. The study included 120 participants, a group of 80 children, aged 9 to 11 years, and a group of 40 adults. In each group, half of the participants were male, the other half female. Blindfolded participants were instructed to make two bars, which were set in different orientations, haptically parallel to each other. They had to parallel the orientation of a reference bar which was felt with their non-dominant hand, at a test bar, that was rotated with their dominant hand. The bars were presented in the mid-horizontal plane at a distance that was set at twice the length of the arm of the participant. The dependent variable was the difference between the orientation of the reference bar and the test bar. The results showed similar deviations for children and adults. In both groups, a significant oblique and gender effect was found, although these effects were more pronounced in the adult group. These results suggest that children aged 9 to 11 years use the same reference frames as adults when paralleling two bars haptically.