Medical College Admission Test (MCAT) Psychological, Social, and Biological Foundations of Behavior (Psych/Soc) Practice Exam

Habituation is defined as a decrease in response after repeated presentations of a stimulus. This phenomenon occurs when an organism becomes accustomed to a stimulus and responds less and less to it over time. For instance, if a loud noise occurs repeatedly in the environment, a person may initially startle at the sound but gradually show less reaction as they become desensitized to it. This process is an essential part of learning and adaptation, allowing individuals to focus on more relevant stimuli while ignoring those that have become predictable and non-threatening.

The other options do not accurately capture the concept of habituation. An increase in response following a stimulus pertains to sensitization, where the response heightens with frequent or intense exposure to a stimulus. The acquisition of new behaviors describes a learning process rather than a decrease in response. Lastly, an immediate response to a novel stimulus refers to an organism's instinctive reaction to something new in its environment, which contrasts with the gradual decrease in response characteristic of habituation.