The Molecule of More: How a Single Chemical in Your Brain Drives Love, Sex, and Creativity―and Will Determine the Fate of the Human Race

by Daniel Z. Lieberman

As with drugs, habituation can also occur with pornography, in which the starting “dose” no longer works as well. When sex addicts were repeatedly shown the same sexual images, their interest diminished. The activity measured in their dopamine circuits also decreased as the images were shown over and over. The same thing happened to healthy males who were repeatedly shown the same pornographic video. When they were shown a new video, their dopamine systems revved up again. This experience of a dopamine rush, followed by a dopamine drop (repeated images), followed by another dopamine rush (new images), pushes addicts to continually seek out fresh material, which may explain why browsing internet sex sites can become compulsive. It’s hard to resist the demands of dopamine circuits, especially with something as evolutionarily important as sex.