Biases in the Visual and Haptic Subjective Vertical Reveal the Role of Proprioceptive/Vestibular Priors in Child Development

Abstract

Investigation of the perception of verticality permits to disclose the perceptual mechanisms that underlie balance control and spatial navigation. Estimation of verticality in unusual body orientation with respect to gravity (e.g., laterally tilted in the roll plane) leads to biases that change depending on the encoding sensory modality and the amount of tilt. A well-known phenomenon is the A-effect, that is a bias toward the body tilt often interpreted in a Bayesian framework to be the byproduct of a prior peaked at the most common head and body orientation, i.e., upright. In this study, we took advantage of this phenomenon to study the interaction of visual, haptic sensory information with vestibular/proprioceptive priors across development. We tested children (5–13 y.o) and adults (>22 y.o.) in an orientation discrimination task laterally tilted 90° to their left-ear side. Experimental conditions differed for the tested sensory modality: visual-only, haptic-only, both modalities. Resulting accuracy depended on the developmental stage and the encoding sensory modality, showing A-effects in vision across all ages and in the haptic modality only for the youngest children whereas bimodal judgments show lack of multisensory integration in children. A Bayesian prior model nicely predicts the behavioral data when the peak of the prior distribution shifts across age groups. Our results suggest that vision is pivotal to acquire an idiotropic vector useful for improving precision when upright. The acquisition of such a prior might be related to the development of head and trunk coordination, a process that is fundamental for gaining successful spatial navigation.

Immersive virtual reality interferes with default head-trunk coordination strategies in young children

“…This is likely due to the weaker reliability of the neck proprioception, which is not mature yet at this developmental stage ( 54–56 ), and which caused the visual inputs to be stronger weighted. This behavioral pattern aligns with recent works showing biases in the perception of visual and haptic verticality to unusual body orientations in younger children ( 57, 58 ), which is here confirmed by the younger participant’s inability to stabilize their head vertically while aligning their torso to lateral target positions. The stronger reliance on the visual system we observed in younger children has been shown to disappear in adults, where immersive VR appears to increase the contribution of proprioceptive and vestibular inputs to postural control over vision ( 59 ).…”

“…This behavioral pattern also comes in line with recent works showing biases in the perception of visual and haptic verticality to unusual body orientations in younger children (58,59), which is here confirmed by the younger participant's inability to stabilize their head vertically while aligning their torso to lateral target positions.…”

Vestibular stimulation and primitive reflex integration may drive multisensory processing: putative principles for a Targeted sensorimotor therapy (TSMT)

“…Concordant to these ndings, is the suboptimal integration of cues for navigation in children younger than 8 years of age [56]. Cuturi and Gori [24] have shown that vision and touch are both in uenced by the same vestibular/proprioceptive priors regarding head and body orientation with respect to gravity.…”

“…This will form the basis of postural and motor coordination, ne motor control and visual processing [21,22]. As such, vestibular signals may be used to disambiguate con icting or inaccurate information by reconciling diverse signals [23,24]. Hence vestibular function forms the basis of postural and motor coordination, as well as gaze stabilization [20,25].…”

Vestibular Stimulation May Drive Multisensory Processing: Principles for Targeted Sensorimotor Therapy (TSMT)

“…This will form the basis of postural and motor coordination, fine motor control and visual processing [18,19]. As such, vestibular signals may be used to disambiguate conflicting or inaccurate information by reconciling diverse signals [20,21]. Hence vestibular function forms the basis of postural and motor coordination, as well as gaze stabilization [17,22].…”