The study showed that the pupil dilation -- widening of the pupils of the eyes -- could be used to indicate levels of stress of a person in a multitasking environment. Many people multitask but currently there is no measurement for someone's mental well-being. However we found that the size of a pupil could be the key to measuring someone's mental state while they multitask said Jung Hyup Kim Assistant Professor from the University of Missouri in the US. To understsand how everyone experiences stress differently the researchers used a simulated oil and gas refinery plant control room where they