Distraction negatively affects traffic behaviour. Particularly activities which involve road users taking their eyes off the road for longer stretches of time increase crash risk: among other things, entering a phone number, texting, reaching for objects in the car, and prolonged glances at objects outside the car.
A recent American analysis, however, showed that talking on a mobile phone (handsfree or handheld) while driving did not increase crash risk; while simulator studies showed that it did adversely affect driving behaviour. A possible explanation of these seemingly contradictory results is that drivers compensate for distraction (for example by only having a phone conversation in less demanding traffic situations).
