Comment Contents Guastello on Hancock Hancock replies Morley on Waterman Serlin on Waterman Friedman on Waterman Churchill and Mruk on Waterman Schneider on Waterman Waterman replies Simms on Pellowski et al
85 86 88 89 89 90 92 92 94
DOI: 10.1(117/30034941
Vigilance Phenomena, Cognitive Workload, and Fatigue Stephen J. Guastello Marquette University This comment offers a solution to two of the problems that Hancock (FebruaryMarch 2013) identified in his integrative review of vigilance research. First, the performance decrement over time that can set in within a half hour of performing a vigilance task in the laboratory is much less likely to occur in real-world conditions; performance improvements have also been noted. Possible explanations for the complex results included intrinsic versus extrinsic motivation, adaptation in long-term job performance, the artificial nature of the occupational or the laboratory task relative to naturalistic vigilance processes, and properties of the signal and noise sources such as signal density over space and time. Second, a paradigm shift in the framing of questions and experimental designs is probably required to further research on these phenomena, which appear to grow in complexity (Hancock, 2013, p. 107). Some new insights on the foregoing issues arise from shifting the focus to cognitive workload and fatigue (CWLF) and treating CWLF as a nonlinear dynamical process instead of a static linear process, as it is commonly rendered in extant experimental designs. CWLF are challenging to untangle and explain within any given context because both occur simultaneously with different temporal dynamics and be-
January 2014 • American Psychologist © 2014 American Psychological Associaüon 0003-066X/14/$ 12.00 Vol. 69. No. 1. 85-95
cause other factors occur over time that improve performance, such as learning, adaptation, and automaticity of the cognitive processes. The nexus of the phenomena has perplexed psychologists for over a century (Ackerman, 2011). A viable theoretical solution is to capture CWLF as two separate cusp catastrophe processes (Guastello, 2003; Guastello, Boeh, et al., 2013; Guastello, Boeh, Schimmels, et al., 2012; Guastello, Boeh, Shumaker, & Schimmels, 2012; Guastello, Malon, et al., 2012; Guastello, Shircel, et al., 2013). The structures of the two models are the same (see Figure 1 ), but the contributing variables are different. Both models account for upward and downward shifts in performance. The models are analytic; the cusp functions can be assessed literally through appropriate statistical analyses and an experimental design that is sufficiently complex to capture all the elements of both models. Elasticity-rigidity in the workload model is analogous to the elasticity of nonlinear materials. When a load is applied to
a horizontal beam, the beam either waffles or remains rigid and eventually snaps. The analogous psychological constructs capture variables related to adaptability or coping strategies. Work speed is primarily a load variable, but it could act as a compensatory ability against fatigue by the operator speeding up or slowing down deliberately, depending on whether the task is high load or low load. Compensatory abilities, more generally, are those that are not necessarily the primary abilities that affect task performance but are those ability areas (of the brain) that could be recruited by the working memory executive when additional workspace is needed. There is an analogy to physical labor whereby upper body strength is often the primary ability, but fatigue in the arms is less if the legs are also stronger. The amount of work done in the fatigue model could derive from either the time spent working between two observation points, workload intrinsic to the target task, performance on a secondary task.
Figure 1 Cusp Catastrophe Models for Effects of Cognitive Workload (Upper Panel) and Fatigue (Lower Panel) on Performance Cusp point-
Response Time Error Rate y stable State^
Elasticity Resilience Adaptability low\ Vertical Load
Cusp point
Work Done Exercise Habits
Compensatory Abiiity
85
or levels of voluntary operator engagement. Some key points that have emanated firom the research thus far are as follows: 1. The experimental manipulations of workload do indeed contribute to the asymmetry parameter of the workload model. 2. The amoutit of work done between two observation points does indeed contribute to the bifurcation parameter of the fatigue model. 3. Elasticity and compensatory ability variables vary with the task situation— episodic, verbal, or pictorial memory; vigilance; financial decisions; dual tasks or conjoint behaviors; and working alone, in cooperation, or in competition with another operator. 4. In the particular case of a vigilance task, frustration was the bifurcation (rigidity) variable in the workload model, and completion of a secotidary task was the bifurcation variable in the fatigue model (Guastello, Malon, et al., 2012). Work speed, which was system driven rather than voluntary, acted as a compensatory ability; slowing down produced smaller increases in errors over time compared to speeding up. 5. Some experimental tasks produced a greater fatigue effect than a workload effect, whereas the opposite was true for other tasks. 6. Time on task was more directly related to fatigue than time on multiple sequential tasks. Future research on CWLF within the nonlinear paradigm should address the following issues: 1. The exploration of elasticity and compensatory ability variables in different types of tasks and task configurations that exist in occupational settings should continue until a full repertoire is achieved. This strategy should allow researchers to transcend some of the artificialities of particular tasks and equipment. 2. The emotional content of work should be explored as a workload variable. 3. Workload dynamics appear to be more closely associated with the workload allocation feature of working memory, and fatigue more closely related to the drain on the executive function of working memory. This pair of connections should be examined more definitively. 4. Variability is an important source of information within the nonlinear paradigm, whereas it is treated as an annoyance in the linear frameworks. Bifurcation of performance trends over time is one manifestation of meaningful variability. Entropy, which can be observed in task and attention switching, is thought to be a precursor to the positive
86
and negative performance shifts noted already, particularly in fatigue. 5. Midstream fatigue and recovery are possible and are thought to be produced by reorganizing the degrees of freedom in task performance and the cognitive schemata used to execute the task (Guastello, Gorin, et al., 2012). 6. Given that vigilance tasks have becotne increasingly widespread, there is experimental evidence that group dynamics and dual (multiple) task assignments can be leveraged against the psychological drain of the primary task (Guastello, Malon, et al., 2012). This proposition should be examined further in the laboratory and in real-world applications. REFERENCES
Ackerman, P. L. (Ed.). (2011). Cognitive fatigue. Washington, DC: American Psychological Association. Guastello, S. J. (2003). Nonlinear dynamics, complex systems, and occupational accidents. Human Factors and Ergonomics in Manufacturing, 13, 293-304. doi:10.1002/hfm.l0045 Guastello, S. J., Boeh, H., Gorin, H., Huschen, S., Peters, N. E., Fabisch, M., & Poston, K. (2013). Cusp catastrophe models for cognitive workload and fatigue: A comparison of seven task types. Nonlinear Dynamics, Psychology, and Life Sciences, 17, 23-47. Guastello, S. J., Boeh, H., Schimmels, M., Gorin, H., Huschen, S., Davis, E., . . . Poston, K. (2012). Cusp catastrophe models for cognitive workload and fatigue in a verbally cued pictorial memory task. Human Factors, 54, 811-825. doi: 10.1177/0018720812442537 Guastello, S. J., Boeh, H., Shumaker, C , & Schimmels, M. (2012). Catastrophe models for cognitive workload and fatigue. Theoretical Issues in Ergonomics Science, 13, 586602. doi:10.1080/1463922X.2011.552131 Guastello, S. J., Gorin, H., Huschen, S., Peters, N. E., Fabisch, M., & Poston, K. (2012). New paradigm for task switching strategies while performing multiple tasks: Entropy and symbolic dynamics analysis of voluntary patterns. Nonlinear Dynamics, Psychology, and Life Sciences, 16, 471-497. Guastello, S. J., Malon, M., Timm, P., Weinberger, K., Gorin, H., Eabisch, M., & Poston, K. (2012, July). Catastrophe models for cognitive workload and fatigue in a vigilance dual-task. Paper presented at the 22nd Annual International Conference of the Society for Chaos Theory in Psychology & Life Sciences, Baltimore, MD. Guastello, S. J., Shircel, A., Poggi, D., Malon, M., Timm, P., Weinberger, K Fabisch, M. (2013, July). Cusp catastrophe models for cognitive workload and fatigue: A new paradigm for studying biases in financial decision making. Paper presented at the 23rd Annual International Conference of the Society for Chaos Theory in Psychology & Life Sciences, Portland, OR. Hancock, P. A. (2013). In search of vigilance: The problem of iatrogenically created psycho-
logical phenomena. American Psychologist, 68, 97-109. doi:10.1037/a0030214
Correspondence concerning this comment should be addressed to Stephen J. Guastello, Department of Psychology, Marquette University, P. O. Box 1881, Milwaukee, WI 532011881. E-mail: [email protected] DOI: IÜ.IÜ37/a0035423
Finding Vigilance Through Complex Explanations for Complex Phenomena P. A. Hancock University of Central Florida Guastello (2014, this issue) offered a sympathetic, meaningful, and potentially explanatory account of several of the issues I raised in my recent article (Hancock, Eebruary-March 2013). My purpose here is to evaluate his offered hypotheses and to see where this intriguing line of development might lead in terms of theoretical and practical understanding of the critical realworld capacity of vigilance. What Guastello correctly identified is that vigilance, or more correctly, the application of human sustained attention to an external task, represents one facet of what Freeman (1948) identified generally as the "energedc" dimensions of human behavioral capacity. Thus, Guastello and I are in direct agreement that the vigilance decrement derives from the high workload imposed, predominantly upon working memory, and that extended or chronic expressions of such performance are certainly related to issues of fatigue (see also Hancock, Desmond, & Matthews, 2012). But Guastello went further and offered a nonlinear, dynamical interpretation of such findings founded upon the corpus of his own work. Clearly, this present brief exchange between us is insufficient to explore the full nuances and complexities of such propositions, so let me again emphasize our strong failure to disagree. Indeed, in an earlier work that, in a number of ways, served as the foundation of the article under discussion, my colleague Joel Warm and I advocated the further exploration of just such an explanation (see Hancock & Warm, 1989, p. 531). With respect to the specific application of such nonlinear dynamical approaches to vigilance, also in earlier work my colleague the late Jim Pierce and I were able to plot the four dimensions of signal detection (SDT) outcome (i.e., hit, miss, correct rejection, and false alarm) using the selfsame model shown in Guastello's
January 2014 • American Psychologist
Copyright of American Psychologist is the property of American Psychological Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
85 86 88 89 89 90 92 92 94
DOI: 10.1(117/30034941
Vigilance Phenomena, Cognitive Workload, and Fatigue Stephen J. Guastello Marquette University This comment offers a solution to two of the problems that Hancock (FebruaryMarch 2013) identified in his integrative review of vigilance research. First, the performance decrement over time that can set in within a half hour of performing a vigilance task in the laboratory is much less likely to occur in real-world conditions; performance improvements have also been noted. Possible explanations for the complex results included intrinsic versus extrinsic motivation, adaptation in long-term job performance, the artificial nature of the occupational or the laboratory task relative to naturalistic vigilance processes, and properties of the signal and noise sources such as signal density over space and time. Second, a paradigm shift in the framing of questions and experimental designs is probably required to further research on these phenomena, which appear to grow in complexity (Hancock, 2013, p. 107). Some new insights on the foregoing issues arise from shifting the focus to cognitive workload and fatigue (CWLF) and treating CWLF as a nonlinear dynamical process instead of a static linear process, as it is commonly rendered in extant experimental designs. CWLF are challenging to untangle and explain within any given context because both occur simultaneously with different temporal dynamics and be-
January 2014 • American Psychologist © 2014 American Psychological Associaüon 0003-066X/14/$ 12.00 Vol. 69. No. 1. 85-95
cause other factors occur over time that improve performance, such as learning, adaptation, and automaticity of the cognitive processes. The nexus of the phenomena has perplexed psychologists for over a century (Ackerman, 2011). A viable theoretical solution is to capture CWLF as two separate cusp catastrophe processes (Guastello, 2003; Guastello, Boeh, et al., 2013; Guastello, Boeh, Schimmels, et al., 2012; Guastello, Boeh, Shumaker, & Schimmels, 2012; Guastello, Malon, et al., 2012; Guastello, Shircel, et al., 2013). The structures of the two models are the same (see Figure 1 ), but the contributing variables are different. Both models account for upward and downward shifts in performance. The models are analytic; the cusp functions can be assessed literally through appropriate statistical analyses and an experimental design that is sufficiently complex to capture all the elements of both models. Elasticity-rigidity in the workload model is analogous to the elasticity of nonlinear materials. When a load is applied to
a horizontal beam, the beam either waffles or remains rigid and eventually snaps. The analogous psychological constructs capture variables related to adaptability or coping strategies. Work speed is primarily a load variable, but it could act as a compensatory ability against fatigue by the operator speeding up or slowing down deliberately, depending on whether the task is high load or low load. Compensatory abilities, more generally, are those that are not necessarily the primary abilities that affect task performance but are those ability areas (of the brain) that could be recruited by the working memory executive when additional workspace is needed. There is an analogy to physical labor whereby upper body strength is often the primary ability, but fatigue in the arms is less if the legs are also stronger. The amount of work done in the fatigue model could derive from either the time spent working between two observation points, workload intrinsic to the target task, performance on a secondary task.
Figure 1 Cusp Catastrophe Models for Effects of Cognitive Workload (Upper Panel) and Fatigue (Lower Panel) on Performance Cusp point-
Response Time Error Rate y stable State^
Elasticity Resilience Adaptability low\ Vertical Load
Cusp point
Work Done Exercise Habits
Compensatory Abiiity
85
or levels of voluntary operator engagement. Some key points that have emanated firom the research thus far are as follows: 1. The experimental manipulations of workload do indeed contribute to the asymmetry parameter of the workload model. 2. The amoutit of work done between two observation points does indeed contribute to the bifurcation parameter of the fatigue model. 3. Elasticity and compensatory ability variables vary with the task situation— episodic, verbal, or pictorial memory; vigilance; financial decisions; dual tasks or conjoint behaviors; and working alone, in cooperation, or in competition with another operator. 4. In the particular case of a vigilance task, frustration was the bifurcation (rigidity) variable in the workload model, and completion of a secotidary task was the bifurcation variable in the fatigue model (Guastello, Malon, et al., 2012). Work speed, which was system driven rather than voluntary, acted as a compensatory ability; slowing down produced smaller increases in errors over time compared to speeding up. 5. Some experimental tasks produced a greater fatigue effect than a workload effect, whereas the opposite was true for other tasks. 6. Time on task was more directly related to fatigue than time on multiple sequential tasks. Future research on CWLF within the nonlinear paradigm should address the following issues: 1. The exploration of elasticity and compensatory ability variables in different types of tasks and task configurations that exist in occupational settings should continue until a full repertoire is achieved. This strategy should allow researchers to transcend some of the artificialities of particular tasks and equipment. 2. The emotional content of work should be explored as a workload variable. 3. Workload dynamics appear to be more closely associated with the workload allocation feature of working memory, and fatigue more closely related to the drain on the executive function of working memory. This pair of connections should be examined more definitively. 4. Variability is an important source of information within the nonlinear paradigm, whereas it is treated as an annoyance in the linear frameworks. Bifurcation of performance trends over time is one manifestation of meaningful variability. Entropy, which can be observed in task and attention switching, is thought to be a precursor to the positive
86
and negative performance shifts noted already, particularly in fatigue. 5. Midstream fatigue and recovery are possible and are thought to be produced by reorganizing the degrees of freedom in task performance and the cognitive schemata used to execute the task (Guastello, Gorin, et al., 2012). 6. Given that vigilance tasks have becotne increasingly widespread, there is experimental evidence that group dynamics and dual (multiple) task assignments can be leveraged against the psychological drain of the primary task (Guastello, Malon, et al., 2012). This proposition should be examined further in the laboratory and in real-world applications. REFERENCES
Ackerman, P. L. (Ed.). (2011). Cognitive fatigue. Washington, DC: American Psychological Association. Guastello, S. J. (2003). Nonlinear dynamics, complex systems, and occupational accidents. Human Factors and Ergonomics in Manufacturing, 13, 293-304. doi:10.1002/hfm.l0045 Guastello, S. J., Boeh, H., Gorin, H., Huschen, S., Peters, N. E., Fabisch, M., & Poston, K. (2013). Cusp catastrophe models for cognitive workload and fatigue: A comparison of seven task types. Nonlinear Dynamics, Psychology, and Life Sciences, 17, 23-47. Guastello, S. J., Boeh, H., Schimmels, M., Gorin, H., Huschen, S., Davis, E., . . . Poston, K. (2012). Cusp catastrophe models for cognitive workload and fatigue in a verbally cued pictorial memory task. Human Factors, 54, 811-825. doi: 10.1177/0018720812442537 Guastello, S. J., Boeh, H., Shumaker, C , & Schimmels, M. (2012). Catastrophe models for cognitive workload and fatigue. Theoretical Issues in Ergonomics Science, 13, 586602. doi:10.1080/1463922X.2011.552131 Guastello, S. J., Gorin, H., Huschen, S., Peters, N. E., Fabisch, M., & Poston, K. (2012). New paradigm for task switching strategies while performing multiple tasks: Entropy and symbolic dynamics analysis of voluntary patterns. Nonlinear Dynamics, Psychology, and Life Sciences, 16, 471-497. Guastello, S. J., Malon, M., Timm, P., Weinberger, K., Gorin, H., Eabisch, M., & Poston, K. (2012, July). Catastrophe models for cognitive workload and fatigue in a vigilance dual-task. Paper presented at the 22nd Annual International Conference of the Society for Chaos Theory in Psychology & Life Sciences, Baltimore, MD. Guastello, S. J., Shircel, A., Poggi, D., Malon, M., Timm, P., Weinberger, K Fabisch, M. (2013, July). Cusp catastrophe models for cognitive workload and fatigue: A new paradigm for studying biases in financial decision making. Paper presented at the 23rd Annual International Conference of the Society for Chaos Theory in Psychology & Life Sciences, Portland, OR. Hancock, P. A. (2013). In search of vigilance: The problem of iatrogenically created psycho-
logical phenomena. American Psychologist, 68, 97-109. doi:10.1037/a0030214
Correspondence concerning this comment should be addressed to Stephen J. Guastello, Department of Psychology, Marquette University, P. O. Box 1881, Milwaukee, WI 532011881. E-mail: [email protected] DOI: IÜ.IÜ37/a0035423
Finding Vigilance Through Complex Explanations for Complex Phenomena P. A. Hancock University of Central Florida Guastello (2014, this issue) offered a sympathetic, meaningful, and potentially explanatory account of several of the issues I raised in my recent article (Hancock, Eebruary-March 2013). My purpose here is to evaluate his offered hypotheses and to see where this intriguing line of development might lead in terms of theoretical and practical understanding of the critical realworld capacity of vigilance. What Guastello correctly identified is that vigilance, or more correctly, the application of human sustained attention to an external task, represents one facet of what Freeman (1948) identified generally as the "energedc" dimensions of human behavioral capacity. Thus, Guastello and I are in direct agreement that the vigilance decrement derives from the high workload imposed, predominantly upon working memory, and that extended or chronic expressions of such performance are certainly related to issues of fatigue (see also Hancock, Desmond, & Matthews, 2012). But Guastello went further and offered a nonlinear, dynamical interpretation of such findings founded upon the corpus of his own work. Clearly, this present brief exchange between us is insufficient to explore the full nuances and complexities of such propositions, so let me again emphasize our strong failure to disagree. Indeed, in an earlier work that, in a number of ways, served as the foundation of the article under discussion, my colleague Joel Warm and I advocated the further exploration of just such an explanation (see Hancock & Warm, 1989, p. 531). With respect to the specific application of such nonlinear dynamical approaches to vigilance, also in earlier work my colleague the late Jim Pierce and I were able to plot the four dimensions of signal detection (SDT) outcome (i.e., hit, miss, correct rejection, and false alarm) using the selfsame model shown in Guastello's
January 2014 • American Psychologist
Copyright of American Psychologist is the property of American Psychological Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
