Alarm reaction patterns by pilots as a function of reaction modality

Past research has demonstrated that operators may lose faith in an alarm system that they deem unreliable. This cry-wolf effect is manifested by slower and less frequent alarm responses. This research examined the effect of reaction modality (manual or vocal) on reactions to alarms of moderate reliability. Twenty-four pilots from the Madison County, Alabama, area performed tracking and monitoring tasks from the Multi-Attribute Task Battery (Parasuraman & Mouloua, 1987) while being presented with alarms, 75% of which were true. Pilots reacted to the alarms during one session using key presses and during another session using voice-activated responses. Analysis of variance and t tests were used to compare speed, accuracy, and frequency of primary and secondary task performances between vocal and manual alarm reactions. Results indicated that participants reacted to alarms more quickly in the manual mode than in the vocal mode; however, participants responded to a greater number of alarms vocally than manually. The results are discussed with regard to human performance theory and aviation applications.