The term psychological refractory period (PRP) refers to the period of time during which the response to a second stimulus is significantly slowed because a first stimulus is still being processed.[1] This delay in response time when one is required to divide attention can exhibit a negative effect that is evident in many fields of study. The PRP can be used to investigate many areas of research that study processes which require divided attention, such as reading aloud, language, or driving and talking on the phone. PRP effects related to personality, age, and level of alcohol or caffeine intake have also been investigated.