The specification of digit and duration during motor programming: a new method of precueing.

This experiment manipulated digit uncertainty, duration uncertainty, and response duration (dit or dah) in a choice reaction time key press task. A new method of precueing was developed that effectively "precued" the digit and/or the duration of the key press task without confounding the number of stimulus response alternatives with the levels of uncertainty of digit and duration. When the duration of the response was certain, there were no RT differences between dit and dah responses, however, when duration was uncertain, RT to dah responses were longer than dit. In addition, level of duration uncertainty and digit uncertainty produced an overadditive interaction upon RT. These results are discussed in terms of generalized motor programs and a feature construction hypothesis. In addition, these results support the view that precueing of movement dimensions can be accomplished without confounding the number of stimulus response alternatives and the uncertainties of movement dimensions.