A critique of the lead article on the effects of practice distribution on motor learning points out that while this is not a new issue, it brings up some important concerns that are not unique to the practice distribution issue but are problems in any investigation of skill learning. (JD)

Use of a retention test in an investigation regarding the post-knowledge of results (KR) interval provides evidence suggesting that, while activity during the post-KR interval is detrimental to performance, no such assumption can be made about its effect on learning. Implications for motor learning and performance are discussed. (Author/PP)