The principle of ___ states that if a stimulus is vivid and real, it will likely change or have an effect on behavior.

The principle of intensity focuses on the idea that the more vivid and real a stimulus is, the greater impact it will have on behavior modification. This principle suggests that experiences or stimuli that are striking, engaging, or emotionally charged are much more likely to catch an individual's attention and, consequently, influence their actions or decisions.

In educational and training contexts, using intense and relevant stimuli—such as realistic scenarios or simulations—can enhance learning outcomes by making the material more relatable and memorable. This concept is integral in developing effective instructional strategies, as it emphasizes the importance of engaging learners through impactful experiences.

In contrast, the other principles revolve around different aspects of behavior change. The principle of relevance pertains to how pertinent the information or experience is to the learner's own life or context. The principle of recency focuses on how recent an experience or information is, impacting its recall. Exercise refers to the practice of applying knowledge or skills, which can also influence learning but is not specifically about the vividness of a stimulus. Thus, intensity stands out as the key principle that ties the vividness of a stimulus to its ability to effect change in behavior.