The fusion point of temporal binding: Promises and perils of multisensory accounts.

Performing an action to initiate a consequence in the environment triggers the perceptual illusion of temporal binding. This phenomenon entails that actions and following effects are perceived to occur closer in time than they do outside the action-effect relationship. Here we ask whether temporal binding can be explained in terms of multisensory integration, by assuming either multisensory fusion or partial integration of the two events. We gathered two datasets featuring a wide range of action-effect delays as a key factor influencing integration. We then tested the fit of a computational model for multisensory integration, the statistically optimal cue integration (SOCI) model. Indeed, qualitative aspects of the data on a group-level followed the principles of a multisensory account. By contrast, quantitative evidence from a comprehensive model evaluation indicated that temporal binding cannot be reduced to multisensory integration. Rather, multisensory integration should be seen as one of several component processes underlying temporal binding on an individual level.

Never run a changing system: Action-effect contingency shapes prospective agency.

Human action control is highly sensitive to action-effect contingencies in the agent's environment. Here we show that the subjective sense of agency (SoA) contributes to this sensitivity as a subjective counterpart to instrumental action decisions. Participants (N = 556) experienced varying reward probabilities and were prompted to give summary evaluations of their SoA after a series of action-effect episodes. Results first revealed a quadratic relation of contingency and SoA, driven by a disproportionally strong impact of perfect action-effect contingencies. In addition to this strong situational determinant of SoA, we observed small but reliable interindividual differences as a function of gender, assertiveness, and neuroticism that applied especially at imperfect action-effect contingencies. Crucially, SoA not only reflected the reward structure of the environment but was also associated with the agent's future action decisions across situational and personal factors. These findings call for a paradigm shift in research on perceived agency, away from the retrospective assessment of single behavioral episodes and towards a prospective view that draws on statistical regularities of an agent's environment.

Does task-irrelevant music affect gaze allocation during real-world scene viewing?

Gaze control manifests from a dynamic integration of visual and auditory information, with sound providing important cues for how a viewer should behave. Some past research suggests that music, even if entirely irrelevant to the current task demands, may also sway the timing and frequency of fixations. The current work sought to further assess this idea as well as investigate whether task-irrelevant music could also impact how gaze is spatially allocated. In preparation for a later memory test, participants studied pictures of urban scenes in silence or while simultaneously listening to one of two types of music. Eye tracking was recorded, and nine gaze behaviors were measured to characterize the temporal and spatial aspects of gaze control. Findings showed that while these gaze behaviors changed over the course of viewing, music had no impact. Participants in the music conditions, however, did show better memory performance than those who studied in silence. These findings are discussed within theories of multimodal gaze control.

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

It has been proposed that statistical integration of multisensory cues may be a suitable framework to explain temporal binding, that is, the finding that causally related events such as an action and its effect are perceived to be shifted towards each other in time. A multisensory approach to temporal binding construes actions and effects as individual sensory signals, which are each perceived with a specific temporal precision. When they are integrated into one multimodal event, like an action-effect chain, the extent to which they affect this event's perception depends on their relative reliability. We test whether this assumption holds true in a temporal binding task by manipulating certainty of actions and effects. Two experiments suggest that a relatively uncertain sensory signal in such action-effect sequences is shifted more towards its counterpart than a relatively certain one. This was especially pronounced for temporal binding of the action towards its effect but could also be shown for effect binding. Other conceptual approaches to temporal binding cannot easily explain these results, and the study therefore adds to the growing body of evidence endorsing a multisensory approach to temporal binding.

How to lose a hand: Sensory updating drives disembodiment.

Body representations are readily expanded based on sensorimotor experience. A dynamic view of body representations, however, holds that these representations cannot only be expanded but that they can also be narrowed down by disembodying elements of the body representation that are no longer warranted. Here we induced illusory ownership in terms of a moving rubber hand illusion and studied the maintenance of this illusion across different conditions. We observed ownership experience to decrease gradually unless participants continued to receive confirmatory multisensory input. Moreover, a single instance of multisensory mismatch - a hammer striking the rubber hand but not the real hand - triggered substantial and immediate disembodiment. Together, these findings support and extend previous theoretical efforts to model body representations through basic mechanisms of multisensory integration. They further support an updating model suggesting that embodied entities fade from the body representation if they are not refreshed continuously.

Sensory attenuation prevails when controlling for temporal predictability of self- and externally generated tones.

Sensory attenuation of self-produced, compared to physically identical but externally produced events is a classical finding in research on perception in action. The most prominent model to explain this effect draws on an internal forward model generating predictions about action outcomes, efference copies, during action planning and initiation. Even though this finding has a long tradition in psychology and neuroscience, several studies have highlighted methodological limitations which open the door for alternative explanations of sensory attenuation effects, most notably in terms of temporal prediction. Here we present an experimental design which carefully controls for this confounding factor. Crucially, we observed the auditory N1 component of the event-related potential to be attenuated for self-generated tones as compared to externally generated tones even when a predictive cue (a bar that is continuously filling up) allows for identical temporal predictability of both events. These findings suggest that voluntary actions do indeed involve a unique, predictive component, affecting the perceptual processing of ensuing events.