Date of Award

Winter 2004

Document Type


Degree Name

Doctor of Philosophy (PhD)



Committee Director

Mark W. Scerbo

Committee Member

Carryl L. Baldwin

Committee Member

Danielle S. McNamara

Committee Member

Frederick G. Freeman


In aviation, effective communication between air traffic control (ATC) and pilots is critical to pilot performance and safety. Problems and limitations of current radio communications initiated the development of datalink technology. Datalink is a text system used to send messages between ATC and pilots. Although datalink was intended to reduce errors associated with radio communication, there are new concerns related to changes in information processing demands associated with executing speech and text ATC commands. In addition, the nature of responses differs between voice and datalink systems. In a voice environment, responses are immediate. However, time delays exist with datalink. These time delays may create an opportunity for interference. Therefore, the timing of interference and the acknowledgement response on command execution performance were examined during the processing of simulated ATC commands. Verbal and central executive (CE) interference tasks were presented before or after the acknowledgement. Participants received both speech and text commands, responded by a verbal or manual acknowledgement, and set the controls in a flight simulator. Results demonstrated no differences between speech and text formats with a verbal acknowledgement. However, there was an advantage for a manual acknowledgement with longer messages. Regarding interference timing, CE as opposed to verbal interference prior to an acknowledgement had a greater negative effect on control setting performance and the magnitude of this effect was larger in the text condition. Thus, text information appears to be more susceptible to the negative effects of interference as resources begin to reach capacity. However, the differences between the sources of interference decreased with an increase in message length. Therefore, the timing and type of interference can have differential effects on resource capacity and the ability to rehearse information in memory. It was also suggested that the processing code of a task is of more importance than the response code. The findings are interpreted within the context of a working memory and resource perspective and implications are discussed with regard to the communication process in aviation.