Defining and measuring pilot mental workload

A theory is sought that is general enough to help the researcher deal with a wide range of situations involving pilot mental stress. A limited capacity theory of attention forms the basis for the theory. Mental workload is then defined as an intervening variable, similar to attention, that modulates or indexes the tuning between the demands of the environment and the capacity of the organism. Two methods for measuring pilot mental workload are endorsed: (1) objective measures based on secondary tasks; and (2) psychophysiological measures, which have not yet been perfected but which will become more useful as theoretical models are refined. Secondary-task research is illustrated by simulator studies in which flying performance has been shown not to be adversely affected by adding a complex choice-reaction secondary task

Using Microworlds to Design Intelligent Interfaces that Minimize Driver Distraction

While recent developments in telematics have produced great interest in driverdistraction, this is hardly a new topic. An early UMTRI report (Treat, 1980)defined internal distraction as a diversion of attention from the driving task that iscompelled by an activity or event inside the vehicle. Based on data collected inMonroe County Indiana, Treat (1980) concluded that internal distraction was afactor in 9% of in-depth reports and 6% of on-site investigations. In the period ofdata collection (1972-1975) conversation with a passenger and increasing use ofentertainment tape decks were the major sources of distraction. Now a host ofmodern infotronic devices offers even greater opportunities for internal distraction(Kantowitz, 2000).Intelligent driver-vehicle interfaces present a wonderful opportunity tosuccessfully manage this increased in-vehicle workload. This smart interfacewould be adaptive, making dynamic allocation of function decisions in real time.Designing such an intelligent interface presents many problems. In particular,since new infotronic devices are being developed and deployed rapidly, it seemsdifficult to evaluate all these new designs. This chapter focuses upon usingmicroworlds to swiftly assess effects of in-vehicle infotronics upon driverdistraction.Microworlds vary along several dimensions such as realism, tractability andengagement (Ehret, Gray, & Kirschbaum, 2000). The traditional drivingsimulator is only one example of a relevant microworld. By considering a widerrange of microworlds, we can gain insight into how to best utilize drivingsimulators. Issues of validity are also illuminated when considered from amicroworld perspective. If appropriate intelligent interfaces are designed,telematics should never increase driver distraction

POPEYE: A production rule-based model of multitask supervisory control (POPCORN)

Recent studies of relationships between subjective ratings of mental workload, performance, and human operator and task characteristics have indicated that these relationships are quite complex. In order to study the various relationships and place subjective mental workload within a theoretical framework, we developed a production system model for the performance component of the complex supervisory task called POPCORN. The production system model is represented by a hierarchial structure of goals and subgoals, and the information flow is controlled by a set of condition-action rules. The implementation of this production system, called POPEYE, generates computer simulated data under different task difficulty conditions which are comparable to those of human operators performing the task. This model is the performance aspect of an overall dynamic psychological model which we are developing to examine and quantify relationships between performance and psychological aspects in a complex environment

Timesharing performance as an indicator of pilot mental workload

Attentional deficits (workloads) were evaluated in a timesharing task. The results from this and other experiments were incorporated into an expert system designed to provide workload metric selection advice to non-experts in the field interested in operator workload

A theoretical approach to measuring pilot workload

Theoretical assumptions used by researchers in the area of attention, with emphasis upon errors and inconsistent assumptions used by some researchers were studied. Two GAT experiments, two laboratory studies and one field experiment were conducted

Objective measure of pilot workload

Timesharing behavior in a data-entry task, similar to a pilot entering navigation data into an on-board computer is investigated. Auditory reaction time as a function of stimulus information and dimensionality is examined. This study has direct implications for stimulus selection for secondary tasks used in the GAT flight simulator at Ames Research Center. Attenuation effects of heat and cold stress in a psychological refractory period task were studied. The focus of interest is the general effects of stress on attention rather than upon specific temperature related phenomena

Attention and automation: New perspectives on mental underload and performance

There is considerable evidence in the ergonomics literature that automation can significantly reduce operator mental workload. Furthermore, reducing mental workload is not necessarily a good thing, particularly in cases where the level is already manageable. This raises the issue of mental underload, which can be at least as detrimental to performance as overload. However, although it is widely recognized that mental underload is detrimental to performance, there are very few attempts to explain why this may be the case. It is argued in this paper that, until the need for a human operator is completely eliminated, automation has psychological implications relevant in both theoretical and applied domains. The present paper reviews theories of attention, as well as the literature on mental workload and automation, to synthesize a new explanation for the effects of mental underload on performance. Malleable attentional resources theory proposes that attentional capacity shrinks to accommodate reductions in mental workload, and that this shrinkage is responsible for the underload effect. The theory is discussed with respect to the applied implications for ergonomics research