On the timing of reference frames for action control.

This study investigated the time course and automaticity of spatial coding of visual targets for pointing movements. To provide an allocentric reference, placeholders appeared on a touch screen either 500 ms before target onset, or simultaneously with target onset, or at movement onset, or not at all (baseline). With both blocked and randomized placeholder timing, movements to the most distant targets were only facilitated when placeholders were visible before movement onset. This result suggests that allocentric target coding is most useful during movement planning and that this visuo-spatial coding mechanism is not sensitive to strategic effects. [ABSTRACT FROM AUTHOR]