title: Cusp catastrophe models for cognitive workload and fatigue: a comparison of seven task types.
abstract: The study introduces a nonlinear paradigm that addresses several unresolved problems  concerning cognitive workload and fatigue: (a) how to separate the effects of workload versus  fatigue, (b) whether the upper boundaries of cognitive channel capacity are fixed or variable,  and how multitasking produces a bottleneck phenomenon, (c) that prolonged time on task can produce  performance decrements but also produce improvements in task performance associated with practice  and automaticity, and that (d) task switching can alleviate fatigue but could be mentally costly.  This study describes two cusp catastrophe models that have become useful for separating the workload  and fatigue performance phenomena and explores the role of task switching and multitasking in both  performance phenomena. In the experiment, 105 undergraduates completed seven computer-based tasks  seven times under one of four experimental conditions: tasks fully alternated, tasks aggregated with  the multitask module performed first, aggregated with the multitask module performed last, and where  the participants chose the task order themselves. Results supported both the cusp models such that  fatigue effects were stronger for tasks with higher memory or attentional demand, and were often  counteracted by practice effects; spelling ability acted as a compensation variable in most cases,  and the intervening amount of work done acted as the bifurcation variable. For cognitive workload,  catastrophic shifts in performance were noted between the single tasks and the multitask, with  relative difficulty of the single task acting as the load (asymmetry) variable and the  flexible task ordering condition as the bifurcation variable.
authors.affiliation: Marquette University, Milwaukee, WI, USA. stephen.guastello@marquette.edu
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Guastello
authors.forename: Henry
authors.initials: H
authors.lastname: Boeh
authors.forename: Hillary
authors.initials: H
authors.lastname: Gorin
authors.forename: Samuel
authors.initials: S
authors.lastname: Huschen
authors.forename: Natalie E
authors.initials: NE
authors.lastname: Peters
authors.forename: Megan
authors.initials: M
authors.lastname: Fabisch
authors.forename: Kirsten
authors.initials: K
authors.lastname: Poston
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention; D003071:Cognition; D005221:Fatigue / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D017711:Nonlinear Dynamics; D013647:Task Performance and Analysis; D016526:Workload / Q000523:psychology* / Q000706:statistics & numerical data; D055815:Young Adult