Every day we are bombarded by stimuli that must be assessed for their potential for harm or
benefit. Once a stimulus is learned to predict harm, it can elicit fear responses. Such learning
can last a lifetime but is not always beneficial for an organism. For an organism to thrive in its
environment, it must know when to engage in defensive, avoidance behaviors and when to
engage in non-defensive, approach behaviors. Fear should be suppressed in situations that
are not dangerous: when a novel, innocuous stimulus resembles a feared stimulus, when a …