Shapes that are rendered invisible through backward masking are still able to influence motor responses: this is called masked priming. Yet it is unknown whether this influence is on the control of ongoing action, or whether it merely influences the initiation of an already-programmed action. We modified a masked priming procedure such that the critical prime-mask sequence was displayed during the execution of an already-initiated goal-directed pointing movement. Psychophysical tests of prime visibility indicated that the identity of the prime shapes (...) were not accessible to participants for conscious report. Yet detailed kinematic analysis of the finger in motion revealed that masked primes had an influence on the pointing trajectories within 277 ms of their appearance, 56 ms earlier than the trajectory deviations observed in response to the visible masks. These results indicate that subliminal shapes can indeed influence the control of ongoing motor activity. (shrink)

We asked whether the influence of an invisible prime on movement is dependent on conscious movement expectations. Participants reached to a central target, which triggered a directional prime–mask arrow sequence. Participants were instructed that the visible arrows would most often signal a movement modification in a specific direction. Kinematic analyses revealed that responses to the visible mask were influenced by participants’ intentional bias, as movements were fastest when the more probable mask was displayed. In addition, responses were influenced by the (...) invisible prime without regard to its relationship to the more probable mask. Analysis of the time of initial trajectory modifications revealed that both primes influenced responses in a similar manner after accounting for participants’ bias. These results imply that invisible stimuli automatically activate their associated responses and that unconscious priming of the motor system is insensitive to the conscious expectations of the participant making the pointing movements. (shrink)

Research suggests that perceptual experience of our movements adapts together with movement control when we are the agents of our actions. Is this agency critical for perceptual and motor adaptation? We had participants view cursor feedback during elbow extension–flexion movements when they actively moved their arm, or had their arm passively moved. We probed adaptation of movement perception by having participants report the reversal point of their unseen movement. We probed adaptation of movement control by having them aim to a (...) target. Perception and control of active movement were influenced by both types of exposure, although adaptation was stronger following active exposure. Furthermore, both types of exposure led to a change in the perception of passive movements. Our findings support the notion that perception and control adapt together, and they suggest that some adaptation is due to recalibrated proprioception that arises independently of active engagement with the environment. (shrink)

Research suggests that the reaching hand automatically deviates toward a target that changes location during the reach. In the current study, we investigated whether movement intention can influence the target jump’s impact on the hand. We compared the degree of trajectory deviation to a jumped target under three instruction conditions: GO, in which participants were told to go to the target if it jumped, STOP, in which participants were told to immediately stop their movement if the target jumped, and IGNORE, (...) in which participants were told to ignore the target if it jumped and to continue to its initial location. We observed a reduced response to the jump in the IGNORE condition relative to the other conditions, suggesting that the response to the jump is contingent on the jump being a task-relevant event. (shrink)