👉 Stimulus is a noun that refers to an action, event, or other factor that triggers a change in a system. In the context of psychology and neuroscience, stimuli are often associated with learning and memory processes. For example, when you receive a pleasant surprise, such as receiving a gift, it can trigger the release of dopamine (a neurotransmitter) in your brain, which is known to be involved in reward and pleasure pathways. This means that the stimulus itself has an effect on how you