Psychological refractory period

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. 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.

PRP is a product of the psychological refractory period paradigm, a paradigm in which two different stimuli are presented in rapid succession, each requiring a fast response.Stimulus onset asynchrony, the time that lapses between the presentations of the two stimuli, acts as the independent variable in this paradigm, and the reaction time to the second stimulus acts as the dependent variable.

An example of a PRP paradigm might be that there is a task 1 which requires participants to push the keyboard-letter ‘n’ with the right index finger when a square frame was green. There is also a task 2 which requires participants to push the keyboard-letter ‘v’ with the left index finger when the digit displayed was a ‘3’ and to push the letter ‘c’ with the left middle finger if the digit displayed was a ‘4’. If the temporal distance between the two tasks is varied, for example 150 ms in one and 1000ms in another, the time to respond to the second task will be longer when the interval occurring between the two tasks is 150 ms than when it is 1000 ms. Referring to figure 1, the SLACK intervening between the execution of the first and second task will be absorbed when the interval intervening between the two tasks is long rather than when it is short.

Researchers have used the PRP paradigm design to study various topics in psychology, and various results indicate how these areas of psychology are negatively affected by the psychological refractory period delay.

PRP is not dependent on personality. Upon experimentation, participants were tested with a PRP paradigm in which the first task was an auditory task and the second task was a visual two choice task. Results indicated that there is an overall decrease in reaction time, exhibiting a psychological refractory period effect, however, there was no effect due to varying levels of extroversion and introversion.

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