Studying speech errors has revealed much about the language production system. We believe it can also be used to investigate the interaction between the speech production and other systems, such as the executive system. This paper studies the effect of focusing attention on the production of a single word in a sequence. We present three experiments in which participants, while reciting four-word tongue twisters, allocate their attention to a particular word either by instruction to avoid errors on that word, to stress the word, or reversely, to recite that word silently instead of overtly. The results of all three experiments consistently show that focusing attention on one word causes a higher error rate on the other words in the sequence.