Home > Human Factors history and studies > Hands-free, eyes-free but cognitive distracted drivers

Hands-free, eyes-free but cognitive distracted drivers

There is a tendency to provide interaction means that keep the driver’s hands and eyes free in a car. An example are mobile phones. The first mobile phones were used in a car like usual, one hand on the phone and in case before selecting the correct number or checking who is calling. Then the hand-free speaking system was invented and options to select a number with the steering wheel.

What remains is still a shared attention. One part still focusing on the street, more like an autopilot fulfilling the known learned actions to drive a car, and the other part involved in the phone call. Talking with someone on the phone opens like a second reality. The mind activates memories on that person and shared knowledge about the topic of conversation.

Cognitive resources like attention and decision making are limited. In shared attention the “auto pilot” might work well for known situations of driving such as following the lane and reaction to traffic lights. However if something unusual happens reaction time increases if the situation has been interpreted correctly or even the perception of the situation is delayed and  any reaction is too late, like a kid chasing a ball.

Donald Norman explained this topics in one of his books and the AAA (American Automobile Association) just released a study validating that fact. The study brought evidence of longer reaction times while talks on the phone. Those are resulting from less scanning of the road and therewith missing cues for happenings in the surroundings like pedestrians (a kind of inattentional blindness).

Source: AAA foundation "Measuring cognitive distraction in the automobile" (June 2013)

Source: AAA foundation “Measuring cognitive distraction in the automobile” (June 2013)

Study composition:
3 experiments, each of them with a single task, a concurrent task listening to a radio, a concurrent task listening to a book on a tape, a concurrent task conversation with a passenger and a concurrent task conversation via a hands-free cell phone.
Performance was measured with NASA TLX, Electroencephalographic activity, response time and accuracy to a peripheral light and event related brain potentials. Those data was combined to a rating system for the cognitive distraction. Low-end is 1 and high-end is 5. The cell phone conversation was rated with 2,27 and the speech-to-text condition with 3,06.

The first experiment solved for the basement assessment. Therefore the participants sat in front of a computer screen with a static cross. They performed the later on concurrent tasks without the driving tasks. The measured workload for each of the tasks contributes to estimate the amount of distraction for the driving task. The experiment two took place in a driving simulator (the participants should follow a pace car through moderate traffic while fulfilling the concurrent tasks) and experiment three in a real car – a Subaru Outback.

Further reading / Sources:

A summary on the dvice website.
A summary on the AAA webpage.
The original paper of the AAA study (53 pages).

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