The role of visual experience in haptic spatial perception: evidence from early blind, late blind, and sighted individuals.

There is contradictory evidence on the effect that visual experience has on haptic abilities. Indeed, some studies have documented that a lack of vision (blindness) results in decreased haptic perception, whereas other studies report an enhanced haptic ability in blind individuals. To examine the role of vision in haptic spatial processing, we recruited early blind, late blind, and sighted participants. Each participant completed a haptic task in which they explored a two-piece LEGO model for eight seconds before searching for the same pieces in a bowl of distractors. Our results showed that blind individuals made more errors than sighted participants. Furthermore, early blind participants performed worse than both late blind and sighted participants, who performed similarly. These findings highlight the importance that vision plays in the development of accurate haptic spatial perception. Additionally, we investigated whether the commonly reported male advantage in haptic tasks depends on visual experience. Our results showed better performance by males in all groups when compared to females. This result suggests that sex differences in haptic spatial processing are a fundamental characteristic of human sensory function, independent of visual experience.Highlights No study has investigated if the previously identified male advantage in haptic spatial processing is mediated by visual experience. Blind participants made more errors than sighted participants; early blind performed the worst. The findings suggest vision is crucial for the development of accurate haptic spatial perception. There was a consistent male advantage in haptic performance across all visual experience groups. Sex differences in haptic spatial ability appear to be independent of visual expertise. Plain language summarySome researchers have suggested that being blind reduces abilities in their other senses, while others believe that a lack of vision can improve them. To further understand which is true, we investigated whether the haptic system-the combination of touch and proprioception (awareness of where the body is in space)-is affected by blindness. To do this, we tested people who were blind from birth (early blind), people who became blind later in life (late blind), and people who can see (sighted) on a simple haptic task. In the task, participants felt a small LEGO model with their hands for eight seconds. Then, they had to find the same LEGO pieces in a bowl filled with other, distractor pieces-using only haptics. We found that blind participants made more mistakes than sighted participants. Those who were blind from birth had the most difficulty. People who became blind later in life performed similarly to sighted individuals. This suggests that vision plays an important role in developing accurate haptic perception. As previous work has shown that males outperform females on haptic tasks, we also investigated whether those differences depended on vision. We found that males performed better than females in all groups, regardless of whether they were blind or sighted. This suggests that sex differences in haptic ability may be a basic feature of how our senses work and not just related to vision.