Effects of Alert Cue Specificity on Situation Awareness in Transfer of Control in Level 3 Automation

Abstract

Drivers in a Level 3 automation environment typically need at least 8 s following a manual takeover request to achieve appropriate levels of situation awareness. Studies that have derived this time estimate use general audio alerts that suggest a transfer of control from the automation to the driver might be required. The current experiment examined if improvements in younger drivers’ situation awareness might be observed in as little as 4 s before a latent hazard might materialize and a transfer of control occurs if more specific audio alerts are used. Younger drivers either drove manually with no cue or in one of four automation conditions: ( a) a general cue condition, ( b) a condition that described the risky features of the roadway and the location of those features, ( c) a condition that contained information about the actual identity of the threat and the required behavior, and ( d) a combination cue condition (both environment and threat cue). Eye movements were recorded as drivers completed six scenarios in a simulated automated driving experiment. The results showed that audio cues that contained information about risky roadway features increased the detection of latent hazards by almost 40% compared with when a general cue or a threat cue was used. Performance with the combined cue was no better than performance with the environment cue. The environment cue gives drivers the critical seconds needed to mitigate a potential crash. Results are informative about which types of alerts to use to inform drivers of upcoming hazards.