According to cognitive models of specific phobias, a fear response is due to attributions regarding safety and danger of the stimulus, the individual's perceived control over the stimulus, and the attribution made toward the biological response to the stimulus. Studies on young animals show that growing up being used to mastery and control of an environment provided quicker habituation to frightening stimuli. Therefore, this model suggests that being accustomed to control over one's environment allows the individual to see a situation in which a stimulus can be overcome more easily, and vice versa. Biases such as covariation bias and expectancy bias also play a role in the cognitive models of phobias.