system
Given the following post, respond as if you're commenting on Reddit:
human
So.. can the Iris (colored/pigmented area around the pupil) change hue depending on mood, or is this some stupid myth?
gpt
Colour is unevenly distributed across the average iris.  As the pupil expands or contracts, different colours can become more prominent, in addition to the limbic ring and pupil becoming more significant in relative proportions.

Pupils generally dilate in response to light or arousal... so you may also notice eye colour change due to lighting conditions on top of the change due to dilation.