A University of Utah study released by the AAA Foundation for Traffic Safety on June 12 was widely reported as concluding that creating text messages by speech was dangerous. The study concluded that texting a friend verbally while behind the wheel caused a “large” amount of mental distraction compared with “moderate/significant” distraction for holding a phone conversation or talking with a passenger and with “small” distraction when listening to music or an audio book. I don’t dispute the findings as stated, but the comparison itself is flawed if used to conclude there is no benefit to creating text messages by voice when driving.

If you are going to text someone while driving, then you are making a decision to compose a message to be delivered while driving. The real question is, once that decision is made, is texting by voice safer than texting by touch keyboard? The answer should be obvious, unless you can type on a mobile phone with one hand without taking your eyes off the road, even if you assume it is equally safe to drive with one hand versus two on the wheel.

Texting is more difficult than speaking or simply listening. You are composing a message intended to be read rather than heard, and you want it to be accurate and clear. The fact that a text message must be short increases the cognitive load as one must think how to deliver a message as briefly as possible. This takes a different level of mental involvement than conversations where a passenger can engage you in quick dialog to clarify a statement, for example.

The difference will be clear to those of us who have used dictation to compose documents. It’s not like talking to a person. You are speaking something to be read as text, which has a high expectation of clarity. Dictation requires effort comparable to composing a document while typing. Dictation of a text message without looking at the display in fact probably requires more concentration than typing a document when you can see the results on a PC screen; when working eyes-free, you don’t see what you have written and must maintain context in your head.

Composing text is clearly more of a mental load than conversing or listening. Concluding that this is the case with a study is not particularly revealing. It has nothing to do with whether, once you have decided to text while driving because it can’t wait, doing it by voice is safer.