Highway hypnosis may stem from the fact that the driving task in highly predictable road situations becomes automatic. This has two consequences. First it makes the task too easy to permit us to invest sufficient effort to maintain a high level of arousal. This gets a low ceiling on the extent to which we can, or will, increase our level of alertness. As a result we may become irresistibly drowsy. Secondly, since automatic task performance is mainly based on internal representations and motor programs and put less emphasis on external feedback, we may fail to act on slowly developing error information.
Samenvatting