Simple in-car route guidance information from another perspective : coding versus modality

A previous field study concerning electronic navigation aids showed an advantage of auditory presentation of route guidance instructions as compared to visual information in terms of navigationel errors (Verwey and Janssen, 1988). In the present paper an experiment is reported that tries to approach the issue of optimal route instructions in a more controlled environment. Under conditions of severe perceptual-motor load subjects were to interpret route instructions with slides depicting real world junctions. The perceptual-motor task consisted of a compensatory tracking task without preview simulating course keeping. Route instructions were composes of either auditory/verbal (e.g. TURN LEFT in spoken language), visual/verbal (e.g. TURN LEFT written on a screen), or visual/spatial (e.g. an arrow on a screen) information. The results showed an advantage for verbal over spatial information. No significant effect of presentation modality was found.