In his analysis of the 'hedonic treadmill,' psychologist Shane Frederick explores why significant life improvements—such as a major promotion or a new home—often fail to produce a lasting increase in subjective well-being. Frederick argues that humans possess a remarkable capacity for sensory and emotional adaptation; once the initial excitement of a positive event fades, the individual's 'happiness set point' quickly adjusts to the new circumstances. Consequently, the individual finds themselves back at their baseline level of satisfaction, ______.