Final answer:
In relation to attention 'external focus' is used when attending to environmental cues or information which sometimes leads to inattentional blindness as shown in the study by Simons and Chabris.
Step-by-step explanation:
In relation to attention, external focus is used when people attend to cues or information in the environment. this involves attending to outside stimuli and processing that information, as opposed to focusing internally on thoughts or feelings. For example the famous study by Simons and Chabris demonstrates how an external focus on the task of counting basketball passes can lead to inattentional blindness where individuals fail to notice an unexpected event (like a person in a gorilla costume) because their attention is directed elsewhere. this example underlines the importance of attention in perception and cognition, highlighting how it can shape our experience of the world around us.