Abstract
When humans indicate on which hand a tactile stimulus occurred, they often err when their hands are crossed. This finding seemingly supports the view that the automatically determined touch location in external space affects limb assignment: the crossed right hand is localized in left space, and this conflict presumably provokes hand assignment errors. Here, participants judged on which hand the first of two stimuli, presented during a bimanual movement, had occurred, and then indicated its external location by a reach-to-point movement. When participants incorrectly chose the hand stimulated second, they pointed to where that hand had been at the correct, first time point, though no stimulus had occurred at that location. This behavior suggests that stimulus localization depended on hand assignment, not vice versa. It is, thus, incompatible with the notion of automatic computation of external stimulus location upon occurrence. Instead, humans construct external touch location post-hoc and on demand.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
New experimental data added to show that the temporal order task employed in the paper does not affect the measurement of interest, i.e., the hand reach-to-point response. Multiple text passages edited, shortened/extended according to comments raised by reviewers in the submission process. Figures revised (same reason). Additions to Supplemental Data.