Human error in medicine contributes to adverse events that threaten patient safety. Certain errors tend to recur across adverse events in health care, reflecting unmet perceptual, cognitive, and behavioural needs as users interact with systems to accomplish patient care goals. For example, slips such as overdosing patients result from inputting the wrong number into infusion pumps or misreading medication orders because critical information is not highlighted or similar symbols are confused on the interface or in the order.