The learning benefits of contextual interference have been frequently
demonstrated in different settings using novice learners. The purpose
of the present study was to test such effects with skilled athletic pe
rformers. Scheduling differences for biweekly additional (''extra'') b
atting-practice sessions of a collegiate baseball team were examined.
30 players (ns = 10) were blocked on skill and then randomly assigned
to one of three groups. The random and blocked groups received 2 addit
ional batting-practice sessions each week for 6 wk. (12 sessions), whi
le the control group received no additional practice. The extra sessio
ns consisted of 45 pitches, 15 fastballs, 15 curveballs, and 15 change
-up pitches. The random group received these pitches in a random order
, while the blocked group received all 15 of one type, then 15 of the
next type, and finally 15 of the last type of pitch in a blocked fashi
on. All subjects received a pretest of 45 randomly presented pitches o
f the three varieties. After 6 wk. of extra batting practice, all subj
ects received two transfer tests, each of 45 trials; one was presented
randomly and one blocked. The transfer tests were counterbalanced acr
oss subjects. Pretest analysis showed no significant differences among
groups. On both the random and blocked transfer tests, however, the r
andom group performed with reliably higher scores than the blocked gro
up, who performed better than the control group. When comparing the pr
etest to the random transfer test, the random group improved 56.7%, th
e blocked group 24.8%, and the control group only 6.2%. These findings
demonstrate the contextual interference effect to be robust and benef
icial even to skilled learners in a complex sport setting.