Action force modulates action binding: evidence for a multisensory information integration explanation

Abstract

Action binding refers to the observation that the perceived time of an action (e.g., a keypress) is shifted towards the distal sensory feedback (usually a sound) triggered by that action. Surprisingly, the role of somatosensory feedback for this phenomenon has been largely ignored. We fill this gap by showing that the somatosensory feedback, indexed by keypress peak force, is functional in judging keypress time. Specifically, the strength of somatosensory feedback is positively correlated with reported keypress time when the keypress is not associated with an auditory feedback and negatively correlated when the keypress triggers an auditory feedback. The result is consistent with the view that the reported keypress time is shaped by sensory information from different modalities. Moreover, individual differences in action binding can be explained by a sensory information weighting between somatosensory and auditory feedback. At the group level, increasing the strength of somatosensory feedback can decrease action binding to a level not being detected statistically. Therefore, a multisensory information integration account (between somatosensory and auditory inputs) explains action binding at both a group level and an individual level.

Temporal binding as multisensory integration: Manipulating perceptual certainty of actions and their effects

“…However, integration is not limited to the spatial dimension, but also affects other attributes such as the intensity (Stein et al, 1996) and the perceived timing of stimuli (Fendrich & Corballis, 2001;Shams, Ma, & Beierholm, 2005). Despite these long-known insights, the-ories of multisensory integration have only recently been applied to the phenomenon of temporal binding, a perceptual illusion in the temporal domain (Cao et al, 2020;Kirsch et al, 2019;Wolpe et al, 2013).…”

“…According to the multisensory approach, this outcome could be due to a higher certainty about the timing of own actions as compared to the timing of external events. Even more strikingly, the magnitude of temporal binding can be manipulated by relatively minor changes in the design, such as delay (Haggard et al, 2002), or the force of a key-press (Cao et al, 2020), which alter neither the action intention nor the causal chain between the action and its effect. Changes in relative cue precision might be responsible for these effects.…”

“…Evidence in favor of the multisensory approach comes from experimental designs that actively manipulated the reliability of effect-related signals (Wolpe et al, 2013), or incidentally influenced the reliability of action-related signals. For example, Cao et al (2020) showed that a light key-press with relatively weak somatosensory feedback is biased more strongly towards an ensuing effect tone than a forceful keypress. The present experiments intended to provide converging evidence from a design that employs a direct manipulation of perceptual precision on both ends of the action-effect episode.…”

Delusional thinking and action binding in healthy individuals

“…Pearson’s correlation was computed between PDI overall score and action binding after possible outliers were excluded using the boxplot rule and the confidence interval of the correlation coefficient was obtained via bootstrapping 25 . In this case only, the individual t-value from the unpaired t-test of the perceived keypress time between AS and AO conditions was used to represent the strength of the individual action binding effect, since the t-value takes into account the variance 5 . Note that the t-value is equally sensitive to individual differences as Cohen’s d when the number of trials is the same among all individuals, which is the case in the current study.…”

“…Alternative accounts to the intention explanation include the causality hypothesis 4 (i.e. the knowledge of action causing its sensory feedback leads to the binding effects) and the cue integration idea 3 , 5 . The cue integration idea assumes that the binding effects are the results of a weighted integration of timing information from the action and the action outcome.…”