Sensorimotor temporal recalibration within and across limbs

Abstract

This is the unspecified version of the paper.This version of the publication may differ from the final published version. Permanent repository link AbstractDeciding precisely when we have acted is challenging, as actions involve a train of neural events spread across both space and time. Repeated delays between actions and consequent events can result in a shift, such that immediate feedback can seem to precede the causative act. Here we examined which neurocognitive representations are affected during such sensorimotor temporal recalibration, by testing if the effect generalises across limbs, and whether it might reflect altered decision criteria for temporal judgements. Hand or foot adaptation phases were interspersed with simultaneity judgements about actions involving the same or opposite limb. Shifts in the distribution of participants' simultaneity responses were quantified using a detection-theoretic model, where a shift of both boundaries together gives a stronger indication that the effect is not simply a result of decision bias. By demonstrating that temporal recalibration occurs in the foot as well as the hand, we confirmed that it is a robust motor phenomenon:Both low and high boundaries shifted reliably in the same-limb conditions. However, in cross-limb conditions only the high boundary shifted reliably. These two patterns are interpreted to reflect a genuine change in how the time of action is represented, and a timing criterion shift, respectively.Keywords: Temporal recalibration, temporal judgement, adaptation, synchrony, action 4 Consider a falling apple. Our subjective experience of this well-known prompt for scientific insight is seamless and unified; the apple appears to fall as a coherent composite of colour, form and motion, before striking the ground with a dull thud. However, from the perspective of a homunculus (or indeed a neuroscientist) looking down upon the brain's activity in response to this sequence of events, the view is of a time-smeared and spatially distributed cacophony of electro-chemical signalling. This viewpoint leaves us wondering how the observer is able to decide with confidence that this particular auditory thud occurred at the same time as that particular visual collision.Science has not yet provided a compelling answer to this question. There is, however, evidence to suggest that recent experience plays an important role, or, put another way, that the temporal relationships that constitute simultaneity can be learnt and relearnt. Several methods exist to try and establish the relative time at which two events appear maximally synchronous (known as the point of subjective simultaneity or PSS). The most common methods require that participants report either the order of two events (a temporal order judgement; TOJ) or whether two or more events occurred synchronously or asynchronously (a simultaneity judgement; SJ). Intriguingly, when brief auditory and visual stimuli are repeatedly presented slightly out of synch during a period of adaptation, participants subsequen...

Effects of Human Synchronous Hand Movements in Eliciting a Sense of Agency and Ownership

“…Some studies investigated the temporal integration window during the elicitation of agency and they found that a delay between an action and its feedback can generate the sense of agency 41,42 . The temporal integration window of perceived agency is even recalibrated along with perceived sensorimotor simultaneity during recalibrated training 11,12,14,15,43 , and sense of agency can in turn influence temporal recalibration 44,45 . However, some limitations should be noted, and these need to be resolved in our future work.…”

Collecting and Interpreting Judgments about Perceived Simultaneity: A Model-Fitting Tutorial

“…For the sj, these approaches generally attempt to place most trials near to the transition boundaries (from succession to synchrony and back again) while still adequately sampling the regions lying both between them and at the extremes. For example, Yarrow et al (2013) used an approach loosely based on Rosenberger and Grill (1997) where the distribution from which trials are selected starts off being uniform, but is modified after each decision based on how the participant responds. The aim is to end up with a bimodal distribution that peaks over both transition boundaries.…”

“…A weaker claim would be that the pss is very likely to lie somewhere between the two criteria. My personal preference is generally to report the two criteria, which may in any case provide greater insights about changes across conditions than a single inferred pss (Yarrow et al, 2013;Yarrow et al, 2011). However, reviewers often request (quite reasonably) that the pss also be reported for easier comparison with the previous literature.…”

“…Only if the full sj model provides a better fit relative to this partial performance model should the participant be retained (c.f. Yarrow et al, 2013).…”

“…This kind of summary is less useful where each soa is only sampled once, as sometimes occurs in situations where soas have a random component. An example would be experiments comparing the time of an action to an event (where the event is presented around the time that the action is expected to occur, but this cannot be known for certain in advance; e.g.,Yarrow, Sverdrup-Stueland, Roseboom, & Arnold, 2013). Another example would be data generated using an adaptive procedure without a fixed step size.…”