Early visual experience influences haptic cross-sectioning ability

Cross-sectioning task requires participants to identify the two-dimensional (2D) internal shape of cross-sectioned three-dimensional (3D) solids. This task demands advanced spatial reasoning abilities, including the mental manipulation of both two-dimensional and three-dimensional objects. While previous research has highlighted the importance of vision in understanding objects' spatial features, the relationship between successful cross-sectioning and visual impairments remains unclear.

The present study aims to investigate how early-life vision guides the ability to construct and transform spatial representations through touch, using a haptic 3D-printed version of the Santa Barbara Solid Test. Our sample consisted of four groups of participants: early blind (N = 11), late blind (N = 8, onset of blindness: after 6 years old), low vision (N = 5, vision acuity between 3/10 and 1/20), and blindfolded sighted (N = 13). All participants were asked to haptically explore and recognize cross-sections of 3D-printed solids of varying difficulty levels (N = 10 trials) and to identify the associated correct section among four options. We analyzed performance using a generalized linear mixed model, with accuracy (correct versus incorrect) as the outcome and group and difficulty as predictors.

The group (i.e., onset of blindness) emerged as the only significant predictor for task performance (p-value < 0.001). In particular, early blind participants show lower probability of correctly identifying cross-section of solids compared to the other groups (all p-values ≤ 0.02).

These findings show that visual deprivation in the first years of life impacts the development of effective haptic spatial skills, highlighting the need for tailored rehabilitation programs, particularly in the context of multisensory spatial reasoning.