Short-Term Memory for Verbal and Graphic Route Information

As road systems become more tortuous, traffic signs giving the necessary short-distance route information become more complex, and place increasing demands on the drivers' short-term memory. An experiment designed initially to study drug effects on drivers' memory for route information revealed that unmedicated, control subjects were able to navigate short routes previously learned as lists of verbal directions, but were unable to navigate completely similar routes previously learned as maps. It was further found that verbal recall of maps, while not perfect, was better than recall by vehicle navigation whether the subject drove or was a passenger, and that the difficulty appeared to involve the spatial nature of maps compared with the “linear” nature of verbal directions. Results from laboratory studies suggest that the difficulty may be due partly to competition between the maps and the driving task for a spatial memory system, and partly to incompatibility between the subjective heading of the driver and the orientations of junctions as remembered and as seen.