Which term describes a simple, automatic response to a sensory stimulus?

The term that describes a simple, automatic response to a sensory stimulus is "reflex." A reflex is an involuntary reaction that occurs rapidly in response to a stimulus without the need for conscious thought. This type of response typically involves a direct pathway through the nervous system, known as a reflex arc, which allows for quick responses that help protect the body from harm or facilitate immediate reactions to changes in the environment.

Reflexes are crucial in many situations, such as pulling your hand away quickly from a hot surface, which illustrates how they help in protecting an organism. This automatic response is fundamental to survival and operates independently of conscious input, making it distinct from learned behaviors, which involve a process of trial and error or conditioning, and instinct, which refers to more complex, innate behaviors that are exhibited by animals.