Abstract
On a daily basis, humans interface with the outside world using judgments of sensorimotor confidence, constantly evaluating our actions for success. We ask, what sensory and motor-execution cues are used in making these judgements and when are they available? Prospective cues available prior to the action (e.g., knowledge of motor noise and past performance), and retrospective cues specific to the action itself (e.g., proprioceptive measurements and uncertainty) provide two timepoints at which to assess sensorimotor confidence. We investigated the inputs available at these two timepoints in a task in which participants reached toward a visual target with an unseen hand and then made a continuous judgment of confidence about the success of their reach. The confidence report was made by setting the size of a circle centered on the reach-target location, where a larger circle reflects lower confidence. Points were awarded if the confidence circle enclosed the true endpoint, with fewer points returned for larger circles. This incentivized attentive reporting and accurate reaches to maximize the score. We compared three Bayesian-inference models of sensorimotor confidence based on either prospective cues, retrospective cues, or both sources of information to maximize expected gain (i.e., an ideal observer). Each participant’s motor and proprioceptive noise were fit based on a motor-awareness task: participants reached repeatedly to a fixed target and reported the perceived endpoint. Our findings showed two distinct strategies: participants either performed as ideal observers, using both prospective and retrospective cues to make the confidence judgment, or relied solely on prospective information, ignoring retrospective cues. Thus, participants make use of retrospective cues in a motor-awareness task, but these cues are not always included in the computation of sensorimotor confidence.