Perceptual load theory

Perceptual load theory explains how our attention works based on the complexity of a task. When we're engaged in a simple task with low perceptual load, our attention is more likely to be distracted by irrelevant stimuli because our cognitive resources are underutilized. Conversely, when the task is complex and demands most of our attention (high perceptual load), we tend to ignore distractions since our mental capacity is fully occupied. In essence, a task’s difficulty influences our ability to notice or tune out other environmental details.