Figure 2. Off-line learning and sequence recall.

(a) Participants initial (skill₁, gray boxes) and later performance on the SRTT (skill₂, black boxes), with associated sequential (square±sem) and random (circle±sem) response times. Following word list learning there was only a fall in sequential response times (paired t-test, t(11) = 6.15, P<0.0001); with no significant change in the random response times (circle±sem, paired t-test, t(11) = 1.79, P = 0.1). Following vowel counting, there was a similar non-specific fall in both sequential (paired t-test, t(11) = 2.54, P<0.05) and random (paired t-test, t(11) = 2.36, P<0.05) response times. (b) These response time changes translated into differential off-line improvements: off-line improvements were induced following word list learning but not following vowel counting (unpaired t-test, t(22) = 2.5, P<0.05). (c) The declarative component of the SRTT was disrupted by learning a word list immediately after the SRTT: those learning a word list recalled on average 4.0±0.8 items (mean±sem) of the 12-item sequence; whereas, those stating the number of vowels within nonsense letter strings were able to recall on average 7.3±0.9 sequence items (unpaired t-test, t(22) = 2.8, P<0.05).