Interference between concurrent speaking and sequential finger tapping: both hands show a performance decrement under both visual and non-visual guidance.

Report that concurrent speaking reduces right hand sequential finger tapping performance selectively only if the movements are guided non-visually. In these replication experiments, concurrent speaking of both rhyme and prose passages reduced performance both of the right and left hand under visual and non-visual guidance. In the replication experiments the performance of the right hand was slightly more reduced by concurrent speaking than was the case for the left hand. The interference effects are interpreted in terms of the temporal constraints imposed by given motor tasks.