The effect of priming on interceptive actions

Planning lane changes using advance visual and haptic information

Taking a motor planning perspective, this study investigates whether haptic force cues displayed on the steering wheel are more effective than visual cues in signaling the direction of an upcoming lane change. Licensed drivers drove in a fixed-base driving simulator equipped with an active steering system for realistic force feedback. They were instructed to make lane changes upon registering a directional cue. Cues were delivered according to the movement precuing technique employing a pair of precues and imperative cues which could be either visual, haptic, or crossmodal (a visual precue with a haptic imperative cue, and vice versa). The main dependent variable was response time. Additional analyses were conducted on steering wheel angle profiles and the rate of initial steering errors. Conditions with a haptic imperative cue produced considerably faster responses than conditions with a visual imperative cue, irrespective of the precue modality. Valid and invalid precues produced the typical gains and costs, with one exception. There appeared to be little cost in response time or initial steering errors associated with invalid cueing when both cues were haptic. The results are consistent with the hypothesis that imperative haptic cues facilitate action selection while visual stimuli require additional time-consuming cognitive processing.

Hitting movement patterns organized by different pitching movement speeds as advanced kinematic information

Conventionally, hitting movements in response to different advanced kinematic information have been investigated from the perspective of chronometric analysis, such as measuring the timing of movements. This is the first study to investigate the effect of manipulating advanced kinematic information on the hitting movement pattern organization based on both kinematics and kinetic analyses in addition to the conventional chronometric analysis. Specifically, the hitting movement of experienced batters in response to visual stimuli consisting of different pitching movement speeds with the same ball trajectory information was measured by an optical motion capture camera system and a foot force sensor inside the shoes. The occurrence timings of specific events (e.g., movement initiation), some kinematic parameters (e.g., maximum rotate angle of the shoulder and hip), and the balance of the ground reaction force between the ball of the big and small toes of both feet were compared between experimental conditions. This was done to test the hypothesis that the hitting movement is coupled with the visual information given to batters based on an expert anticipatory model. The results indicated that for a faster pitching speed, the batter tended to react with a significantly smaller preparatory movement (e.g., smaller weight shift and shoulder rotate angle during backswing) and put significantly larger weight on the rear foot during the swing execution phase. The situation was exactly reverse in the case of a slower pitching movement. These results suggest for the first time that manipulating advanced kinematic information not only affects the timing of the movement, but also the whole-body kinematics and lower body kinetics. The results also indicate that the hitting movement pattern of experienced batters is highly dependent on the advanced kinematic information.

Continuously updating one’s predictions underlies successful interception

This paper reviews our understanding of the interception of moving objects. Interception is a demanding task that requires both spatial and temporal precision. The required precision must be achieved on the basis of imprecise and sometimes biased sensory information. We argue that people make precise interceptive movements by continuously adjusting their movements. Initial estimates of how the movement should progress can be quite inaccurate. As the movement evolves, the estimate of how the rest of the movement should progress gradually becomes more reliable as prediction is replaced by sensory information about the progress of the movement. The improvement is particularly important when things do not progress as anticipated. Constantly adjusting one’s estimate of how the movement should progress combines the opportunity to move in a way that one anticipates will best meet the task demands with correcting for any errors in such anticipation. The fact that the ongoing movement might have to be adjusted can be considered when determining how to move, and any systematic anticipation errors can be corrected on the basis of the outcome of earlier actions.

Potential of rapid adjustment of brief interceptive action using predicted information

Interceptive actions, such as hitting a ball in baseball or tennis, feature a moving target whose parameters (i.e., velocity or trajectory) differ across trials. This means that players are required to make rapid trial-by-trial adjustments. The purpose of this study was to determine whether a brief interceptive action could be adjusted using predicted sensory consequence of movement (pSCM) information, even under severe time constraints where the participants could not adjust their movement using only visual feedback. Participants performed an interceptive action for targets with two different velocities with different occurrence probabilities (20%, 50%, and 80%). Prior to movement onset, we applied transcranial magnetic stimulation (TMS) to the supplementary motor area (SMA), as TMS of the SMA is known to disrupt pSCM activity. We hypothesized that if pSCM information were used to adjust the motor parameters of a brief interception, then TMS would significantly increase the constant temporal error (i.e., the difference between the sum of reaction time and movement time and the total target visible time) for a target velocity with a low probability (20%). This hypothesis is based on the previous findings that the pSCM plays an important role in the adjustment of relatively brief interception. We found that while interceptions that lasted about 250 ms after movement onset were unaffected, interceptions that lasted about 350 ms after movement onset could be influenced by TMS. However, TMS interfered with performance provided that the delivery of the pulse occurred 100 ms before movement onset. This finding suggests that pSCM information that is used for a rapid adjustment is generated only in that specific time interval.

Catching what we can't see: manual interception of occluded fly-ball trajectories

Control of interceptive actions may involve fine interplay between feedback-based and predictive mechanisms. These processes rely heavily on target motion information available when the target is visible. However, short-term visual memory signals as well as implicit knowledge about the environment may also contribute to elaborate a predictive representation of the target trajectory, especially when visual feedback is partially unavailable because other objects occlude the visual target. To determine how different processes and information sources are integrated in the control of the interceptive action, we manipulated a computer-generated visual environment representing a baseball game. Twenty-four subjects intercepted fly-ball trajectories by moving a mouse cursor and by indicating the interception with a button press. In two separate sessions, fly-ball trajectories were either fully visible or occluded for 750, 1000 or 1250 ms before ball landing. Natural ball motion was perturbed during the descending trajectory with effects of either weightlessness (0 g) or increased gravity (2 g) at times such that, for occluded trajectories, 500 ms of perturbed motion were visible before ball disappearance. To examine the contribution of previous visual experience with the perturbed trajectories to the interception of invisible targets, the order of visible and occluded sessions was permuted among subjects. Under these experimental conditions, we showed that, with fully visible targets, subjects combined servo-control and predictive strategies. Instead, when intercepting occluded targets, subjects relied mostly on predictive mechanisms based, however, on different type of information depending on previous visual experience. In fact, subjects without prior experience of the perturbed trajectories showed interceptive errors consistent with predictive estimates of the ball trajectory based on a-priori knowledge of gravity. Conversely, the interceptive responses of subjects previously exposed to fully visible trajectories were compatible with the fact that implicit knowledge of the perturbed motion was also taken into account for the extrapolation of occluded trajectories.