On a variant of Stroop's paradigm: which cognitions press your buttons?

The Stroop effect typically refers to the fact that the time to identify the color of a visually presented word is affected by the relationship between the word and the color. When the (irrelevant) word is semantically related to the color (e.g., the wordgreen, presented in red) response time is slower than if the word is neutral or unrelated. One question that has been posed concerns whether semantics plays a role only when the task requires an explicit verbal response, or whether it also plays a role when the response is manual. Sharma and McKenna (1998) have reported that semantics plays a role only when the response is vocal. A reanalysis of their data shows that semantics also plays a role when manual responses are made.