The effect of congruency between sound-source location and verbal message semantics of in-vehicle navigation systems

In-vehicle navigation systems use an auditory interface to avoid redirecting drivers’ visual attention when interaction with the devices is required. Since most of these systems emit sounds from the installation location of the devices, there are situations when the sound-source location conflicts with the message’s semantics. This research studied the effect of congruency on recall accuracy and response time after a distraction period during which participants had to perform a modified Brown–Peterson task. Three conditions of verbal message presentation methods were tested: to left-ear only (PL), to right-ear only (PR), and to one of the ears according to the message semantics (PS), in which message content was either “left” or “right”. Three distraction intervals were also tested. The results indicated that the length of the distraction interval significantly reduced response time, suggesting an expectancy effect in the presence of distractions. The presentation condition did not have significant effect on error rate. The data were further divided into two conditions: the congruent condition, which was equivalent to PS, and the conflicting condition, for PL and PR. The analysis showed that the congruent/conflicting condition significantly affected the error rate; the data revealed that congruent condition had a lower error rate. The findings have implications for the design of verbal messages with semantics that are spatial in nature.