Visual information about past, current and future properties of irregular target paths in isometric force tracking.

In visual-motor tracking, information about past, current, and future properties of a target path can be available but, because they are typically manipulated independently, the relative contribution of these information categories to tracking performance is not well understood. The aim of the current study was to investigate the role of visual information pertaining to past, current, and future states of the target path in guiding isometric tracking performance as a function of the irregularity of the target path (sine wave, brown/pink noise, white noise). The findings from local and global properties of the force output showed that the role of visual information about the past, current, and future states of target paths is dependent on the regularity of the signal to be tracked. The brown/pink noise pathway condition was most strongly influenced by future and past-future visual information for both local error properties (lead/lag, root mean square error (RMSE)) and global properties of the force output (ApEn, cross correlation). The highly irregular white noise pathway did not benefit from past or future information and the highly regular sine wave was only influenced for the local error properties of RMSE and lead/lag. It appears that visual information about past and future tracking states is more effective with a pathway that is middling with respect to regularity/irregularity. This is consistent with the role of visual information in tracking to be dependent on the potential adaptability for change in the dimension of the motor output.