Which term refers to a complex behavior that is rigidly patterned throughout a species and is unlearned?

The term that describes a complex behavior that is rigidly patterned throughout a species and is unlearned is instinct. Instincts are innate behaviors that organisms are born with, which means they do not need to be acquired through experience or practice. These behaviors are generally consistent across members of the same species and occur in response to specific stimuli in the environment.

For example, many animals exhibit specific mating rituals or parenting behaviors instinctively, displaying a set pattern of actions that is crucial for their survival and reproduction. Instincts can be more complex than simple reflexes, often involving a series of behaviors that are executed in a specific sequence.

In contrast, learned behavior involves acquiring new skills or responses through experience, which inherently differs from instinct. A reflex is an involuntary and immediate response to a stimulus, but it is typically much simpler than an instinctive behavior. A conditioned response is a learned reaction that occurs through the process of conditioning, which also indicates that it is not innate. Therefore, instinct is correctly defined as a behavior that is inherently programmed in an organism, making it unlearned and universally recognized within the species.