Abstract
This paper deals with the claim made by McLeod and Hume (this issue) that, for a skilled typist, the rate of responding is controlled by a limit on the number of responses that can be executed simultaneously, not by a limit on response selection. I point out that McLeod and Hume's observations are consistent with various interpretations, including one in which response rates are limited by response selection. I also note the importance of trying to distinguish structural and strategic bottlenecks in speeded responding.