Cognitive fatigue and workspaces: what open-plan offices don’t show

The experts

From an ergonomic perspective, fatigue cannot be reduced to mere weariness or a lack of motivation. Rather, it is a functional state that deteriorates when the resources mobilised to meet the demands of work become insufficient — or simply too costly to sustain over time. Put another way, fatigue is not just a question of the ‘quantity’ of work: it also depends on how the environment, the organisation and the actual activity combine to place demands on the individual (Hockey, 2013; Peytcheva, 2025).

This is where the ICA model proposed by Édith Galy is particularly illuminating. By linking the Individual, Mental Load and Activity, it encourages us to view fatigue not as the effect of a single cause, but as the result of a balance—sometimes a fragile one—between several dimensions. The Individual component encompasses the resources available at a given moment, determined by individual cognitive, affective, physiological and social factors. The Mental Load component comprises four categories of mental load. Intrinsic load corresponds to the demands inherent in the task, time load to the time constraints imposed on the individual, and organisational load to organisational requirements and the social atmosphere. A fourth category, relevant mental load, corresponds to the cost of implementing regulatory strategies to cope with organisational and temporal constraints. Finally, the Activity component refers to the characteristics of the tasks to be performed, which determine the task’s intrinsic load, and to the execution context, the elements of which determine the temporal and organisational loads (Galy, 2016; Galy, 2020; Galy, Cariou, & Mélan, 2012).

In open-plan offices, the mental strain of managing one’s workload becomes a key factor. Work is not merely about carrying out a task. It also involves constantly maintaining focus, picking up where one left off in a train of thought; filtering out nearby conversations; responding to an unexpected request; reprioritising, and then returning to the original task as if nothing had happened. This extra effort leaves little trace in office layouts and largely escapes conventional performance indicators. Yet it has a direct impact on employees’ experience and their ability to maintain sustained productivity without burning out.

This is where the concepts of vigilance and nervous tension become particularly useful. Vigilance refers to a state of arousal that is conducive to sustaining attention. When it is sufficiently high, it helps the individual to resist distractions, remain engaged, and maintain — at least temporarily — an acceptable level of performance (Mackworth, 1948; Thayer, 1986). One might say that it constitutes a resource for ‘stamina’: it supports the regulation of fatigue. But this resource is neither stable nor infinite. It fluctuates depending on the time of day, the workload, the quality of recovery, and the specific conditions under which the activity is performed (Åkerstedt & Folkard, 1995).

Nervous tension, on the other hand, is of a different nature. It involves a more constrained, more strained form of mobilisation, often linked to the effort to keep going despite mounting demands and repeated disruptions. In the short term, it can compensate for a drop in alertness: we ‘buckle down’, we push ourselves, we hold on. But when this tension persists, it itself becomes a factor in burnout. Energy is no longer invested in the core of the work; it is consumed in maintaining a level of control that has become costly. And it is often at this point that fatigue becomes more apparent: reduced mental availability, irritability, difficulty refocusing, a feeling of being overwhelmed, and a gradual reduction in room for manoeuvre (Van der Linden, Frese, & Meijman, 2003; Peytcheva, 2025).

In this process, the sound environment plays a major role — but not solely through average sound levels. What causes fatigue is also the variability of sounds, their unpredictability, and above all their informational content. Intelligible speech attracts attention, even when one is trying to ignore it. A nearby conversation, a phone call, or repeated exchanges involuntarily draw on cognitive resources and increase the effort required to stay focused. The literature is clear on this point: in open-plan offices, and particularly when speech is intelligible, concentration deteriorates and performance declines on tasks requiring sustained attentional control (Banbury & Berry, 2005; Hongisto, 2005; Jahncke, Hygge, Halin, Green, & Dimberg, 2011).

Ultimately, what open-plan offices do not always reveal is not just the noise. It is the invisible effort of adaptation that they demand. On the surface, work continues: employees respond, cooperate, mediate and produce. But this continuity often relies on a series of silent compensations. However, when an environment forces individuals to draw on more resources over the long term, and then to rely on an increasingly taxing nervous strain, fatigue is no longer a matter of individual fragility. It becomes a sign of an overly demanding adjustment between the person’s functional state and the constraints of the situation.

For those involved in commercial property and spatial design, the challenge is therefore very real. Designing an effective workspace is not just about optimising square metres or encouraging interaction. It is also about creating conditions for cognitive sustainability: enabling concentration, limiting unnecessary interruptions, providing opportunities for retreat, tailoring atmospheres to specific tasks, and recognising that actual activity is never limited to what the space dictates. Thinking about the environment in terms of the triad of Individual–Mental Load–Activity means putting actual work back at the centre. And this is probably an essential condition for preventing fatigue in the long term.

 

Selected bibliography

Banbury, S., & Berry, D. C. (2005). Office noise and employee concentration: Identifying causes of disruption and potential improvements. Ergonomics, 48(1), 25-37.

Galy, E. (2016). Approche integrative de la charge mentale de travail : une echelle d'evaluation basee sur le modele ICA (Individu-Charge-Activite).

Galy, E. (2020). A multidimensional scale of mental workload evaluation based on Individual-Workload-Activity model: Validation and relationships with job satisfaction. The Quantitative Methods for Psychology, 16(3), 240-252.

Galy, E., Cariou, M., & Melan, C. (2012). What is the relationship between mental workload factors and cognitive load types? International Journal of Psychophysiology, 83(3), 269-275.

Hockey, G. R. J. (2013). The Psychology of Fatigue: Work, Effort and Control. Cambridge University Press.

Hongisto, V. (2005). A model predicting the effect of speech of varying intelligibility on work performance. Indoor Air, 15(6), 458-468.

Jahncke, H., Hygge, S., Halin, N., Green, A. M., & Dimberg, K. (2011). Open-plan office noise: Cognitive performance and restoration. Journal of Environmental Psychology, 31(4), 373-382.

Mackworth, N. H. (1948). The breakdown of vigilance during prolonged visual search. Quarterly Journal of Experimental Psychology, 1(1), 6-21.

Peytcheva, V. (2025). Approche transactionnelle de la fatigue en bureau et espace ouverts de travail. These de doctorat, Universite Cote d'Azur.

Thayer, R. E. (1986). Activation-Deactivation Adjective Check List: Current overview and structural analysis. Psychological Reports, 58(2), 607-614.

Van der Linden, D., Frese, M., & Meijman, T. F. (2003). Mental fatigue and the control of cognitive processes: Effects on perseveration and planning. Acta Psychologica, 113(1), 45-65.

Akerstedt, T., & Folkard, S. (1995). Validation of the S and C components of the three-process model of alertness regulation. Sleep, 18(1), 1-6.

Release date: April 2026