The stimulus in this scenario is the act of dimming the lights in the room. The response is the reflex arc, which involves the sensory neurons detecting the change in light and sending signals to the central nervous system (the brain). The brain then processes this information and sends signals back to the muscles that control the pupils in the eyes to constrict in response to the decreased light, allowing the eyes to adjust to the new lighting conditions. This reflex arc helps to protect the eyes from sudden changes in light and maintain optimal vision.
