The role of consciously timed movements in shaping and improving auditory timing

Our subjective sense of time is intertwined with a plethora of perceptual,
cognitive, and motor functions, and likewise, the brain is equipped to
expertly filter, weight, and combine these signals for seamless
interactions with a dynamic world. Until relatively recently, the
literature on time perception has excluded the influence of motor
activity, yet, it has been found that motor circuits in the brain are at
the core of most timing functions. Several studies have now identified
that concurrent movements exert robust effects on perceptual timing
estimates, but critically, have not assessed how humans consciously judge
the duration of their own movements. This creates a gap in our
understanding of the mechanisms driving movement-related effects on
sensory timing. We sought to address this gap by administering a
sensorimotor timing task in which we explicitly compared the timing of
isolated auditory tones and arm movements, or both simultaneously. We
contextualized our findings within a Bayesian cue combination framework,
in which separate sources of temporal information are weighted by their
reliability and integrated into a unitary time estimate that is more
precise than either unisensory estimate. Our results revealed differences
in accuracy between auditory, movement, and combined trials, and
crucially, that combined trials were the most accurately timed. Under the
Bayesian framework, we found that participants’ combined estimates were
more precise than isolated estimates in a way that trended towards
optimality, while being overall less optimal than the model’s prediction.
These findings elucidate previously unknown qualities of conscious motor
timing and propose computational mechanisms that can describe how
movements combine with perceptual signals to create unified, multimodal
experiences of time.