The gradual disappearance of a conditioned response is known as extinction. When extinction occurs, the bond between the stimulus and response, in the is case gummy worms and fear, is diminished or even extinguished. This can occur when gummy worms are presented in a manner that does not cause fear or causes less fear as the exposures continue.
Often, in a treatment plan to eliminate undesired responses or behaviors, an instructor or therapist will try to determine why a response or behavior exists. In this case, the person working with Yamaki would investigate the reasons he or she has a fear response towards gummy worms. Once the cause is isolated, a way of presenting the stimulus that will either not trigger the response or offer an alternative response can be used to lessen the association between the gummy worms and the fear.
If the desire is to increase fear of gummy worms, the opposite would be done. A secondary stimulus that would increase the fear towards gummy worms would need to be presented simultaneously each time the gummy worms were presented. This would recondition Yamaki to respond with fear towards the gummy worms.