Figure 1.

A. Target array with representation of spatial error, target direction, movement area and hand-path length. Normalized area, an index of path overlap, was measured as the ratio between movement area and the squared hand-path length.

B. Movements to unpredictable and predictable targets. In the case of unpredictable target, as in R blocks, movements always start after tone and target presentation. Movement time (MT) is measured as the time between the movement onset and the reversal. Response time is the sum of onset time (OT) and MT. Instead, when target can be predicted as in CCW blocks, the out and back movement starts before tone and target occurrence, resulting in negative onset times (OT) and shorter or negative response time.

C. Schematic illustration of the development of anticipatory movements during sequence learning. Tones and targets are presented at a constant time interval of 1 second, so that the temporal occurrence, but not the spatial location, is always predictable. At the beginning (a.), movements must be initiated by responding in reaction time to the target appearance. In the course of learning (b.), movements start before target (boxed hand-paths). Finally, when the sequence is entirely knows (c.), all target appearances are anticipated.