| The safe and efficient management of an airline is a complex cognitive task involving many individuals working in close coordination. Unfortunately, the current models and assumptions upon which airline operations support systems are designed are not appropriate for dynamic work environments such as airline operations, and are not consistent with the activities observed there. A new way to approach the design of support systems is proposed whereby the system is viewed as a joint-cognitive system where human cognition must regulate two dynamic systems simultaneously, i.e., the internal system (the human) and the external system, e.g., the flight schedule as they both change in response to context. In this thesis a model of control which consists of three contextual control modes (CCMs) is used as a framework to represent the changes in patterns of behavior in response to context. Using this framework the thesis demonstrates three distinct contributions. First, it provides a theoretical foundation relating the high level constructs of contextual control modes to engineering design. Second, it formulates a method of designing cognitive work support systems using the CCMs. Third, it demonstrates these capabilities and benefits of CCM in a relevant domain.;The thesis begins by examining the evolution of human performance modeling from the initial stimulus-response methods introduced during the industrial revolution to model factory worker productivity, continues with a discussion of the information processing model where human cognition was modeled as a series of actions carried out in a predefined order, and ends with the concept of cognitive control whereby cognition is not considered a context-free mental process but modeled as an individual's ability to maintain control under varying contexts and to counter the effects of disturbances. The results from a preliminary evaluation conducted to determine if CCMs could be measured and if they provided any additional insight cognitive work are presented, and reveal that CCMs could be measured and the self-assessed CCM varied as predicted. A design process is developed which utilizes the CCMs as representing specific patterns of activity, thus specifying the design requirements. Following this design process, a prototype is created and evaluated using a controlled experiment to examine the effectiveness of the CWSS. The experiment examines performance, workload, and patterns of activity, and has several interesting findings. The first is that performance was independent of the almost all of the predictors and covariates including participant's Self-assessed CCM, with the exception of CCM transitions. As in the preliminary study, participants who reported transitioning between CCMs also reported decreased performance, increased frustration and actually performed worse. Second, perceived performance varied linearly with a participant's self-assessed CCM, but not with the actual performance. Third, participants report lower levels of effort when using a CWSS DM that matched their operational CCM. Finally, the design process successfully created a CWSS with DMs which support strategic and tactical CCMs. Unfortunately, no specific performance improvements were found for cases where the participant's CCM matched the DM as hypothesized, calling into question the effectiveness of creating different design modes for performance improvement.;This thesis presents two methods for measuring CCMs: one direct single scale and one indirect composite scale. The measurements correlate highly. Both have a high degree of face validity and user acceptance. In the end, the composite measure may be a more robust measure of CCM because it provides a greater degree of diagnosticity by specifically inquiring after different aspects of CCM and is less susceptible to an individual's interpretation of the relative importance of the multiple dimensions of CCMs included in the definitions. |
