Has anyone ever noticed that sometimes when a person is trying really hard to pay attention to you, their pupils dilate...and I don't think this is related to the intake of light (i.e. it is not night time when this is going on) What exactly is this all about?

does anyone have an explanation?

Hi duch84,

when people are paying attention, their pupils dilate in order to let a large amunt of light enter, spreading the perception of the visual scene. In this way, the information kept from the eyes to the brain is larger.

Moreover, You may read something in the NLP (Neuro Linguistic programming) about how to use this sign in everyday life.

Cheers

There is a body of psychological research that uses pupil dilation as a measure of attention or interest. In some experiments, subjects are asked to view various pictures while their gaze direction and pupil dilation are recorded.

maybe you are in fear ))) and you sympathetic activity is raised )

It has been shown that the activity of the norepinephrine system is correlated with pupil diameter. Norepinephrine is one of the 4 main neuromodulators (the four being acetylcholine, norepinephrine, dopamine, and serotonin). Acetylcholine and norepinephrine are both highly correlated with attention, and are believed to mediate various aspects of task-relevant direction of perception.

Norepinephrine in particular is believed to mediate "vigilance", which can be thought of as noticing the environment, or giving priority to new sensory information from the environment. Increases in norepinephrine, which is released from the locus coerulus, are known to correlate with increase pupil diameter size. So perhaps this is one explanation.

The relationship between norepinephrine and pupil diameter is mentioned in this review of the norepinephrine system by Gary Aston-Jones and Jonathan Cohen (2005) in Annual Reviews of Neuroscience:

http://www.csbmb.princeton.edu/ncc/publica...sAnnRev2005.pdf