H567/03 Section B Option 3 - Ergonomics and cognitive overload

When work exceeds processing capacity

A worker can receive more information than they can use at once. Ergonomics studies how to fit tasks, equipment and environments to human abilities and limitations. Cognitive ergonomics concerns attention, memory and decision making: a well-designed workstation helps the worker notice and interpret relevant information.

Capacity is limited, whereas competing demands can rise. A control-room operator may have to remember an unfinished instruction, interpret several changing readings and respond to a telephone call. Each demand competes for attention and working memory. Switching away from the instruction can leave its final step unperformed. This is a mechanism connecting design to errors; it does not mean the worker has lost all ability to think.

The environmental-overload account has four linked ideas. People have limited capacity for incoming stimuli. When demands exceed capacity, some information receives less processing. Intense, unpredictable or uncontrollable stimuli are especially likely to capture attention. Continued demands can temporarily reduce available attentional capacity, making later overload more likely. A loud unexpected alarm can therefore attract attention even when a quiet trend on another screen is more relevant.

More information is not automatically better information. A display can preserve essential readings while reducing the mental work needed to combine them. Conversely, removing a necessary warning in the name of simplicity can make the task less safe.

Designing around cognitive limits

Workplace design should reduce unnecessary processing while preserving the information needed for the job. Grouping related readings places the evidence for one decision together. Showing a trend beside the current value reduces the need to remember earlier values. Consistent labels and locations reduce searching, and a clear task sequence helps a worker resume after interruption. These proposals follow from cognitive mechanisms rather than from a preference for an attractive screen.

For example, a dispatch dashboard could put the delivery deadline, vehicle location and delay trend in one labelled panel. The dispatcher can compare related information directly instead of searching separate pages and remembering each value. A visible marker for the last completed check can support resumption after a call. This is an illustrative proposal, not a reported result of a dispatch experiment.

The cognitive area explains the information-processing link. The biological area can explain how sleep loss or prolonged stress changes a worker's available capacity; this links ergonomics to the earlier shift-work and environmental-stress topics. The social area also matters when interruptions arise from team communication. A cognitive explanation is therefore useful without implying that all errors are caused by the screen alone.