In four field experiments the participants drove an instrumented car provided with a hands-free phone and performed several cognitive tasks while driving including phone conversations. The study focussed the cognitive component of the conversations, excluding dialling. The cognitive demands of the conversations were varied and in two of the experiments the same tasks had two versions: by phone and in live conversation with the experimenter in the car. Several dependent measures like visual search behaviour, driving speed, visual detection and response selection capacities and others were analysed. Like in previous experiments of the same authors the more demanding cognitive tasks produced higher interference effects, but when the same tasks performed by phone were compared with its live versions no differences were observed. Once the manual phone operation has been technically suppressed the risk of phone conversations relies on the demands of the message content and its equivalent to talking to a passenger. Implications for safety are discussed. (Author/publisher).
Samenvatting