Pupil dynamics refers to the changes in the size of the pupil, the opening in the center of the iris that controls the amount of light entering the eye. These changes occur in response to various factors, including light levels, emotional states, and cognitive load. When exposed to bright light, the pupil constricts (becomes smaller) to protect the retina, while in dim light, it dilates (becomes larger) to allow more light in. The size of the pupil can also be influenced by autonomic nervous system responses. For instance, during moments of excitement or stress, the pupil may dilate due to increased sympathetic nervous system activity. Conversely, relaxation can lead to constriction. Understanding pupil dynamics can provide insights into a person's emotional and cognitive state.