Context and relevance. Accuracy of object distance estimation in a distant space is affected by the integration of visual, proprioceptive, and vestibular information. Objective: examining the contribution of visual, proprioceptive and vestibular information in estimating the egocentric distance of an object in peripersonal space. Hypothesis. Reliance on the integration of visual and proprioceptive information will predominantly affect the accuracy of estimating the distance of objects in peripersonal space. Methods and materials. 22 participants were estimating egocentric distances of a stimulus, positioned on 20, 40 and 60 cm. Three tasks were used: the guidance task GT (including visual information), the verbal assessment task VAT (visual information and higher cognitive processes), and the motor reproduction task MRT (visual and proprioceptive information). In half of the experimental situations, the subjects were rotated around their vertical axis, which caused the deprivation of vestibular information. Results. Results indicate that the subjects most accurately estimated the stimulus distance when they integrated visual and proprioceptive information (MRT). When relying only on visual information, respondents overestimated stimulus distance (GT), while relying on a combination of visual information and higher cognitive processes when estimating distance (VAT), subjects consistently underestimated distance. Deprivation of vestibular information reduce differences in estimation errors between the three tasks. Conclusions. The accuracy of distance estimation relies on the integration of all information available to them from the senses in order to estimate egocentric distance as accurately as possible.
Jakšić et al. (Tue,) studied this question.