The following contains a frank, though non-graphic, discussion of pornography addiction. Parents are therefore cautioned to examine the material themselves before sharing it with children or teenagers.

“Because the human brain is the biological anchor of our psychological experience, it is helpful to understand how it operates,” says William M. Struthers, associate professor of psychology at Wheaton College. “Knowing how it is wired together and where it is sensitive can help us understand why pornography affects people the way it does.” Here are 9 things you should know about pornography affects the brain.

1. Sexually explicit material triggers mirror neurons in the male brain. These neurons, which are involved with the process for how to mimic a behavior, contain a motor system that correlates to the planning out of a behavior. In the case of pornography, this mirror neuron system triggers the arousal, which leads to sexual tension and a need for an outlet. “The unfortunate reality is that when he acts out (often by masturbating), this leads to hormonal and neurological consequences, which are designed to bind him to the object he is focusing on,” says Struthers. “In God’s plan, this would be his wife, but for many men it is an image on a screen. Pornography thus enslaves the viewer to an image, hijacking the biological response intended to bond a man to his wife and therefore inevitably loosening that bond.”

2. In men, there are five primary chemicals involved in sexual arousal and response. The one that likely plays the most significant role in pornography addiction is dopamine. Dopamine plays a major role in the brain system that is responsible for reward-driven learning. Every type of reward that has been studied increases the level of dopamine transmission in the brain, and a variety of addictive drugs, including stimulants such as cocaine, amphetamine, and methamphetamine, act directly on the dopamine system. Dopamine surges when a person is exposed to novel stimuli, particularly if it is sexual, or when a stimuli is more arousing than anticipated. Because erotic imagery triggers more dopamine than sex with a familiar partner, exposure to pornography leads to “arousal addiction” and teaches the brain to prefer the image and become less satisfied with real-life sexual partners.

3. Why do men seek out a variety of new explicit sexual images rather than being satisfied with the same ones? The reason is attributed to the Coolidge effect, a phenomenon seen in mammalian species whereby males (and to a lesser extent females) exhibit renewed sexual interest if introduced to new receptive sexual partners, even after refusing sex from prior but still available sexual partners. This neurological mechanism is one of the primary reasons for the abundance and addictiveness of Internet pornography.

4. Overstimulation of the reward circuitry—such as occurs with repeated dopamine spikes related to viewing pornography—creates desensitization. As Gary Wilson explains, “When dopamine receptors drop after too much stimulation, the brain doesn’t respond as much, and we feel less reward from pleasure. That drives us to search even harder for feelings of satisfaction—for example, by seeking out more extreme sexual stimuli, longer porn sessions, or more frequent porn viewing—thus further numbing the brain.

5. “The psychological, behavioral, and emotional habits that form our sexual character will be based on the decisions we make,” says Struthers. “Whenever the sequence of arousal and response is activated, it forms a neurological memory that will influence future processing and response to sexual cues. As this pathway becomes activated and traveled, it becomes a preferred route—a mental journey—that is regularly trod. The consequences of this are far-reaching.”

6. What makes Internet porn unique? Wilson identifies a number of reasons, including: (1) Internet porn offers extreme novelty; (2) Unlike food and drugs, there are almost no physical limitations to Internet porn consumption; (3) With Internet porn one can escalate both with more novel “partners” and by viewing new and unusual genres; (4) Unlike drugs and food, Internet porn doesn’t eventually activate the brain’s natural aversion system; and (5) The age users start watching porn. A teen’s brain is at its peak of dopamine production and neuroplasticity, making it highly vulnerable to addiction and rewiring.

7. Men’s exposure to sexually explicit material is correlated with social anxiety, depression, low motivation, erectile dysfunction, concentration problems, and negative self-perceptions in terms of physical appearance and sexual functioning.

8. The following video offers a brief overview of the affect of pornography on the brain.

9. In this video, Gary Wilson discusses the disturbing symptoms showing up in some heavy Internet porn users, the surprising reversal of those symptoms, and the science behind these phenomena. Although it is not presented from a Christian perspective, the discussion is highly recommended for better understanding the deleterious and wide-ranging effects pornography has on men.