Hitting moving targets with a continuously changing temporal window

Abstract

Hitting a moving target requires that we do not miss the target when it is around the aimed position. The time available for us not to miss the target when it is at the position of interest is usually called the time window and depends on target's speed and size. These variables, among others, have been manipulated in previous studies but kept constant within the same trial or session. Here, we present results of a hitting task in which targets underwent simple harmonic motion, which is defined by a sinusoidal function. Target velocity changes continuously in this motion and so does the time window which is shorter in the centre (peak velocity) and longer at the turning points (lowest velocity) within a single trial. We studied two different conditions in which the target moved with a reliable (across trials) amplitude displacement or reliable peak velocity, respectively, and subjects were free to decide where and when to hit it. Results show that subjects made a compromise between maximum and minimum target's speed, so that they did hit the target at intermediate speed values. Interestingly, the reliability of target peak velocity (or displacement) modulated the point of interception. When target's peak velocity was more reliable, subjects intercepted the target at positions with smaller temporal windows and the reverse was true when displacement was reliable. Subjects adapted the interceptive behaviour to the underlying statistical structure of the targets. Finally, in a control condition in which the temporal window also depended on the instant size and not only on speed, subjects intercepted the target when it moved at similar speeds than when the size was constant. This finding suggests that velocity rather than the temporal window contributed more to controlling the interceptive movements.

Integration of speed and time for estimating time to contact

“…It is also consistent with numerous imaging and electrophysiological studies that find an important role for premotor and supplementary motor areas in timing ( 59 – 63 ). In contrast, temporal cues may not play an active role during the adjustments that follow movement initiation when the brain has access to movement-related, state-dependent information ( 64 – 66 ).…”

Grasping in One-Handed Catching in Relation to Performance

“…the hand [ 43 – 45 ], the hitter tool [ 46 – 48 ] or the fingers in our case, depending on the task requirements. A possible explanation of our results is that moving faster allowed participants to reduce the effects of timing errors [ 12 , 13 , 46 , 49 , 50 ], and thus it is likely that contacting the ball at the time of highest hand closing speed increased success probability.…”

“…A possible explanation for the observed unimodal distribution of PvClose for the touched trials ( Fig 9 , panel B), is that, in case of underestimated PvClose, participants were able to capture the ball also after it impacted on the palm and bounced off, hence gaining extra time for grasping motion execution. Similar to other interceptive tasks [ 12 , 13 , 47 ], ball capture in our experiment required to execute hand closing within a limited time window, which depended on ball velocity, size of the ball, the size of the hand defining a "catchable volume" ( Fig 11 ). For a successful grasping movement, a spatial error could be tolerated as long as the ball was within this catchable volume when the participants reached the final grip configuration.…”

“…However, to date, a systematic analysis of the possible sources of errors underlying unsuccessful catching is lacking. Because of the spatial and temporal constraints involved, the smallest error in any component of the interceptive action could lead to an unsuccessful catch [ 12 , 13 ]. What are the interception components that affect catching performance most?…”

Drift-diffusion explains response variability and capacity for tracking objects

“…Time to contact (TTC), which is the time it takes for an object to reach an observer or a particular place, is an important factor in a variety of real-world situations, such as catching and hitting balls in games, driving vehicles, or passing through a busy street. The ability to estimate TTC for one object has been assessed in several studies (for example see [1][2][3][4][5][6][7][8][9][10][11][12][13][14]). The accuracy and precision of TTC estimation is related to the time perception ability, which is considered in several studies [6,11,[15][16][17][18][19][20][21][22][23][24].…”