On the day harvey is to present his dissertation, he wakes up with a severe head ache. during the presentation, he felt no pain in his head. not until 15 minutes after the presentation is over does harvey become aware of his head ache again. harvey's occurrence is best explained by:

Harvey has had en episode of Gate-control theory. The gate control theory of pain asserts that non-painful input closes the "gates" to painful input, which prevents pain sensation from traveling to the central nervous system. Therefore in Harvey's case, his presentation was so stimulating to him that the experience and moment of it suppressed his pain momentarily.