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Article Excerpt
INTRODUCTION
In modern workplaces, people commonly have to deal with increasingly complex problems, such as managing a big company, finding the fault in a power plant, and learning a new computer program without specific instructions. Although in practice many of these tasks can be executed with routines or through the use of standardized procedures, there are also many complex tasks for which routines or procedures are not directly available or that need ad hoc actions that go beyond formal procedures. Dealing with such nonroutine tasks often requires exploration to gain insight into the task and to find out which actions can accomplish task goals (Funke, 1991). Exploration can be done in a systematic or unsystematic way (Dorner, 1980). Exploring systematically means that people behave in a goal-directed way and reflect on action feedback and on their own behavior (Trudel & Payne, 1995; van der Linden, Sonnentag, Frese, & van Dyck, 2001). In contrast, when exploring unsystematically, people often behave in an unstructured way and do not seem to follow a coherent path toward goal attainment (Dorner, 1980). Instead, actions are executed impulsively or are guided by external stimuli that tend to capture attention (see Hollnagel, 1993).
An important factor in whether people explore in a systematic or unsystematic way is their level of task engagement. Task engagement refers to the level of cognitive resources (e.g., attention) allocated to task-relevant processes; these processes involve problem-solving steps such as goal setting, hypothesis formation, planning, and feedback evaluation (Dorner, 1980; Trudel & Payne, 1995). When many resources are allocated to problem solving, exploration is likely to be goal directed and systematic. In contrast, when task engagement is low, this tends to manifest itself in the use of unsystematic exploration strategies, which may generally be ineffective or inefficient (Green & Gilhooly, 1990). Although many factors can influence the level of task engagement, in the current study we focus on one of these factors--namely, mental fatigue. Specifically, we measure exploration behavior and assess how systematic versus unsystematic behavior changes under fatigue. As far as we know, no other study has explicitly investigated exploration under fatigue. Nevertheless, knowing how exploratory behavior may change under fatigue is important because exploration is a substantial part of problem solving in complex tasks (Dorner, 1980; Hollnagel, 1993; Shrager & Klahr, 1986).
Mental Fatigue and Exploration Behavior
Mental fatigue can be defined as a psychophysiological state resulting from sustained performance on cognitively demanding tasks and coinciding with changes in motivation, information processing, and mood (e.g., Meijman, 2000). One of the main characteristics of mental fatigue is an increased resistance against further effort and a tendency to reduce task engagement (Holding, 1983; Meijman, 2000; Sanders, 1998). Thus, if possible, fatigued people will stop working on effortful tasks and postpone the work until they are no longer fatigued. However, even in situations where they cannot stop working, fatigued people still tend to reduce task engagement (often unintentionally; Meijman, 2000; Sanders, 1998). Such reduced task engagement will not manifest itself as a complete withdrawal from the task or as a complete breakdown of performance. More likely, periods of adequate performance will more frequently be alternated with lapses of task engagement under fatigue (Sanders, 1998). During such lapses, behavior may be directed not by clear task goals but by more automatic cognitive processes (see Monsell & Driver, 2000). With regard to exploration behavior, it can be expected that during those lapses, people will not show thoughtful, systematic exploration.
Before being to able to study exploration under fatigue, it is necessary to establish what are the behavioral manifestations of systematic and unsystematic exploration. Therefore, in the following sections we describe three major types of exploration behavior we assess in the current study. With these three types of exploration, we do not intend to exhaustively cover all possible forms of exploration behavior; rather, we want to capture broad patterns of behavior that people show when working on complex, nonroutine tasks (Hollnagel, 1993; Trudel & Payne, 1995). We labeled these types of exploration behavior systematic exploration, unsystematic trial and error, and rigid behavior.
Systematic exploration implies that a person explores a system in a goal-directed, coherent way (Green & Gilhooly, 1990; Trudel & Payne, 1995). This means that hypotheses about where to search for and about possible outcomes of actions are generated and that behavior is guided by these hypotheses (Shrager & Klahr, 1986). Moreover, exploring systematically implies reflection on action feedback and on working methods. Several studies support the importance of goal-directed, reflective behavior for successful exploration (Chi, Bassok, Lewis, Reimann, & Glaser, 1989; Shrager & Klahr, 1986; Trudel & Payne, 1995). For example, Trudel and Payne analyzed verbalizations of people who explored a digital stopwatch; they found that "good" explorers (the ones who learned much about the watch) tended to verbalize discoveries they made earlier, frequently assessed what had been learned so far, and often confirmed or disconfirmed feedback. In general, using systematic exploration involves a thoughtful, reflective approach to the task (Trudel & Payne, p. 325). As such, it can be argued that systematic exploration involves a relatively high level of engagement. However, as mental fatigue coincides with a reduction in task engagement (e.g., increased lapses of task engagement), it can be expected that the use of systematic exploration will decrease under fatigue (Hypothesis 1).
Unsystematic trial and error refers to exploration that is unstructured and does not seem to be guided by clear hypotheses; nor is it accompanied by signs of reflection (Hollnagel, 1993; Trudel & Payne, 1995). During unsystematic trial and error, people often shift from one subgoal to another, and none or only a few of these subgoals are well considered. In the literature on problem solving and human-computer interaction (HCI) there are many reports of such behavior, even though different labels have been assigned to it--for example, vagabonding (D6rner, 1980), scrambled mode (Hollnagel, 1993), and unsystematic trial and error (Trudel & Payne, 1995). In general, unsystematic trial and error may coincide with a withdrawal of cognitive resources from hypotheses formation, planning, and reflection. Moreover, as the tendency to reduce task engagement increases under fatigue, it can be expected that the use of unsystematic trial and error will also increase under fatigue (Hypothesis 2).
Rigid behavior is characterized by decreased cognitive flexibility and increased tendency to perseverate. During periods of rigid behavior, actions or ideas are often initially guided by habits or by salient cues that capture attention. Based on such habits or cues, people relatively quickly adopt certain action patterns in which they persist, even though feedback clearly indicates that this is no longer useful (Dorner, 1980; van der Linden et al., 2001). Rigid behavior is another specific type of unsystematic behavior often reported in the problem-solving and HCI literature. For example, in a study on learning a statistical program through exploration, Green and Gilhooly (1990) found that poor learners show a tendency to repeat methods, to pay less attention to feedback,...
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