Programming of action timing cannot be completed until immediately prior to initiation of the response to be controlled

We consider, in depth, findings from across 6 decades regarding generating a motor response in a simple reaction-time (i.e., delayed response) paradigm. The early results robustly show a response complexity effect whereby the more response elements, the longer the simple reaction time (RT). This effect is puzzling because it indicates that preparation of some aspect of a response cannot be completed prior to the simple RT interval even though a...