Figure 1. Experimental Design.

Participants were trained, tested (skill₁) on the SRTT, and then either learnt a list of words or were asked to state the number of vowels within nonsense letter strings. Following a 12-hr interval participants were retested (skill₂) on the SRTT, and finally asked to declaratively recall items from the sequence. Skill was measured by comparing the response times of the sequential trials (white blocks) against those of the random trials (gray blocks). The interval between testing (skill₁) and word list learning was extended to 4-hr in one control group while in another the interval between testing and retesting was reduced to 30 minutes.