Tactile awareness changes when you lie down.

Unwalla, K., Cadieux, ML & Shore, DI Lying down alters tactile awareness. SCI Rep 11, 13479 (2021). https://doi.org/10.1038/s41598-021-92192-1

Commentary

Accurate localization of touch requires the integration of two frames of reference: internal (e.g. anatomical) and external (e.g. spatial).

This study was designed to investigate the integration of these two frames of reference using a tactile temporal order judgment task with hands crossed in the midline.

They manipulated the reliability of visual and vestibular information, both of which contribute to the external reference frame. Visual information was manipulated across experiments.

Experiment 1 was conducted with full vision, while Experiment 2 was conducted wearing a blindfold.

Vestibular information was manipulated in both experiments by having two groups of participants complete the task in both upright and lying down positions.

A Bayesian hierarchical model was used to estimate the perceptual weights applied to these frames of reference. We found that participants who were lying down reduced the weight applied to the external reference frame and reduced the deficit.

Blindfolding also resulted in a similar reduction, and these findings conclude to emphasize the importance of the visual system in weighting the tactile reference frames, and the importance of the vestibular system in this integration.