Earliest successful learning could be shown for groups (s) and (D-6), with highly significant differences ( p < 0.001) in their RT reduction (SD) between the first and second block of practice with 143.5 (15.0) ms and 227.5 (53.1) ms, respectively.
The difference between (D-6) and (D-5) interestingly approached significance ( p = 0.052).
Among the treatment groups, a definite trend in learning success can be outlined: group (D-6) as the most successful group was markedly better than all other groups, except for the second most effective group, (D-4-2).