Kielan Yarrow, Ingvild Sverdrup-Stueland and Derek Arnold
Repeated presentation of artificially induced delays between actions and events leads to shifts in participants’ subjective simultaneity towards the adapted lag. This sensorimotor temporal recalibration generalises across sensory modalities, presumably via a shift in the motor component. Here we examined two overlapping questions regarding (1) the level of representation of temporal recalibration (by testing whether it also generalises across limbs) and (2) the neural underpinning of the shift in the motor component (by comparing adaption magnitude in the foot relative to the hand). An adaption-test paradigm was used, with hand or foot adaptation, and same-limb and cross-limb test phases that used a synchrony judgement task. By demonstrating that temporal recalibration occurs in the foot, we confirmed that it is a robust motor phenomenon. Shifts in the distribution of participants’ synchrony responses were quantified using a detection-theoretic model of the SJ task, where a shift of both boundaries together gives a stronger indication that the effect is not simply a result of decision bias. The results showed a significant shift in both boundaries in the same-limb conditions, whereas there was only a shift of the higher boundary in the cross-limb conditions. These two patterns most likely reflect a genuine shift in neural timing, and a criterion shift, respectively.