- The task-Invoked pupillary response refers to the changes in pupil size that occur during cognitive tasks, reflecting levels of arousal and cognitive load. This phenomenon is characterized by pupil dilation and constriction in response to task demands, behavioural performance, and unexpected events. - It's used often in research to check for things that you would normally require brain scans for. For example to see if someone is in a flow state. ---- https://en.wikipedia.org/wiki/Task-invoked_pupillary_response