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Abstract:
Imagine changing lanes on a motorway, and in particular the series of angles through which the steering wheel passes in completing the manoeuvre. The vast majority of us describe turning the wheel once and then returning the wheel to the middle position. This is wrong, because we have failed to describe the appropriate symmetrical motion of the steering wheel in the opposite direction required to straighten the car. To investigate this misconcept and so as to determine the type of motor programs used during steering, we tested the ability of subjects to change lanes with and without visual feedback. Five licensed drivers drove in a simulated environment projected on a 180° screen using a force-feedback steering wheel. A straight four-lane motorway appeared alternately with normal (daylight) or zero visibility (dark tunnel). In both conditions subjects were asked to change lanes—either to the left or to the right. In the condition without visual feedback no other feedback about performance was given.
Without visual feedback the results showed a predictable increase in variance in the final heading but also suggested a systematic deviation of heading towards the direction of the lane change (p<0.001), due to the subjects' failure to complete the lane changing manoeuvre. Hence, we conclude that despite the highly practised nature of the task of lane changing, it is not stored as a complete motor program, but is instead achieved by the interplay of a simple steering program and visual feedback about current heading and location on the road.
