Academic journal article Human Factors

The Out-of-the-Loop Performance Problem and Level of Control in Automation

Academic journal article Human Factors

The Out-of-the-Loop Performance Problem and Level of Control in Automation

Article excerpt


The out-of-the-loop performance problem has been widely documented as a potential negative consequence of automation (Billings, 1991; Moray, 1986; Wickens, 1992; Wiener and Curry, 1980). System operators working with automation have been found to have a diminished ability both to detect system errors and subsequently to perform tasks manually in the face of automation failures, compared with operators who manually perform the same tasks. This paper will explore the possible etiologies of this phenomenon and potential means for ameliorating the problem.

The out-of-the-loop performance can be linked to two major issues associated with the implementation of automation: loss of manual skills and loss of awareness of the state and processes of the system.

Loss of Skills

The loss of manual skills is a major concern accompanying the introduction of automation. Shift (1983), for instance, found that despite initial manual training, those subjects who had been operating as supervisory controllers of automation in a simulated process control task were slower and more inefficient in bringing the system under control than were subjects who had operated only in a manual mode. Weiner and Curry (1980) cited concerns by aircraft flight crews that a loss of proficiency will occur with extensive use of automatic equipment. The fear is that manual skills will deteriorate with lack of use and flight crews will no longer be proficient at manual operations when needed. Wiener (1988) reported that in response to these concerns pilots are routinely operating in a manual mode in order to maintain flight skills.

There is also a concern that appropriate skills may not be developed if operators learn to operate with automated systems initially, without benefit of extensive manual experience. Moray (1986), building on the work of Rasmussen (1981, 1983) and Bainbridge (1981) discussed the need to provide operators with appropriate models. "If the operator has been trained exclusively for outer-loop control and is suddenly required to close an inner loop in an emergency when the automatic systems fail, this will be impossible" (Moray, 1986, p. 40/36). This has become a concern in automated aircraft, where new pilots may have little opportunity to acquire or practice manual skills or may not take full advantage of the opportunities they do have (Orlady and Wheeler, 1989).

These skills may be important not only for performing a task manually, but also for detecting the need for manual performance. In research relevant to this issue, Kessel and Wickens (1982) investigated the detection of system failures as evidenced by changes in dynamics associated with an automated tracking task. Although detection of changes in system dynamics in the manual mode was always superior to that in the automated mode, prior experience with operating in the manual mode led to superior performance in the automated mode when compared with the performance of subjects who had operated only with the system in the automated mode. Kessel and Wickens attributed this finding to the development of internal models when subjects were operating in the manual mode. These models directed subjects' attention to important cues that were also relevant in the automated mode. They did not find that internal models developed in the automated mode transferred to performance in the manual mode; those subjects performed significantly worse when switched to the manual mode. This finding supports the importance of manual experience in developing skills relevant to the detection of automation failures.

Loss of Situation Awareness

It is the central thesis of this paper that a loss of situation awareness (SA) underlies a great deal of the out-of-the-loop performance problem (Endsley, 1987). Situation awareness is defined as "the perception of elements in the environment within a volume of time and space, the comprehension of their meaning, and the projection of their status in the near future" (Endsley, 1988, p. …

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