Trading Later Rewards for Current Pleasure: Pornography Consumption and Delay Discounting (2015)
Comments: This paper (abstract below) contains two longitudinal studies examining the effects of Internet porn on "delay discounting." Delay discounting happens when people choose ten dollars right now rather than 20 dollars in a week. It's the inability to delay immediate gratification for a more valuable reward in the future.
Think of the famous Stanford marshmallow experiment, where 4 and 5 year olds were told if they delayed eating their one marshmallow while the researcher stepped out, they would be rewarded with a second marshmallow when the researcher returned. Watch this funny video of kids struggling with this choice.
The first study (median subject age 20) correlated subjects' pornography use with their scores on a delayed gratification task. The results:
"The more pornography that participants consumed, the more they saw the future rewards as worth less than the immediate rewards, even though the future rewards were objectively worth more."
Put simply, more porn use correlated with less ability to delay gratification for larger future rewards. In the second part of this study researchers assessed the subjects delayed discounting 4 weeks later and correlated with their porn use.
"These results indicate that continued exposure to the immediate gratification of pornography is related to higher delay discounting over time."
Continued porn use resulted in greater delayed discounting 4 weeks later. This strongly suggests that porn use causes inability to delay gratification, rather than the inability to delay gratification leading to porn use. But the second study drove the nail into the coffin.
A second study (median age 19) was performed to assess if porn use causes delayed discounting, or the inability to delay gratification. Researchers divided current porn users into two groups:
- One group abstained from porn use for 3 weeks,
- A second group abstained from their favorite food for 3 weeks.
All participants were told the study was about self-control, and they were randomly chosen to abstain from their assigned activity.
The clever part was that the researchers had the second group of porn users abstain from eating their favorite food. This ensured that 1) all subjects engaged in a self-control task, and 2) the second group's porn use was unaffected.
At the end of the 3 weeks, participants were involved in a task to assess delay discounting. Important note: While the "porn abstinence group" viewed significantly less porn than the "favorite food abstainers", most did not completely abstain from porn viewing. The results:
"As predicted, participants who exerted self-control over their desire to consume pornography chose a higher percentage of larger, later rewards compared to participants who exerted self-control over their food consumption but continued consuming pornography."
The group that cut back on their porn viewing for 3 weeks displayed less delay discounting than the group that abstained from their favorite food. Put simply, abstaining from internet porn increases porn users' ability to delay gratification. From the study:
"Thus, building on the longitudinal findings of Study 1, we demonstrated that continued pornography consumption was causally related to a higher rate of delay discounting. Exercising self-control in the sexual domain had a stronger effect on delay discounting than exercising self-control over another rewarding physical appetite (e.g., eating one’s favorite food).
- It wasn't exercising self-control that increased the ability to delay gratification. Reducing porn use was the key factor.
- Internet porn is a unique stimulus.
- Internet porn use, even in non-addicts, has long-term effects.
What's so important about delay discounting (the ability to delay gratification)? Well, delay discounting has been linked to substance abuse, excessive gambling, risky sexual behavior and internet addiction.
Back to the 1972 "marshmallow experiment": Researchers reported that the children who were willing to delay gratification and waited to receive the second marshmallow ended up having higher SAT scores, lower levels of substance abuse, lower likelihood of obesity, better responses to stress, better social skills as reported by their parents, and generally better scores in a range of other life measures (the follow-up studies here, here, and here). The ability to delay gratification was critical for success in life.
This new porn study turns everything on its head. While the marshmallow studies point to the ability to delay gratification as an unchangeable characteristic, this study demonstrates it's fluid, to some degree. The surprising finding is that exercising willpower was not the key factor. Instead, exposure to Internet porn affected subjects' ability to delay gratification. From the study:
"Our results also bolster findings that differences in delay discounting are largely due to behavior rather than genetic predispositions."
"While developmental and biological predisposition may play a major role in one’s discounting and impulsivity tendencies, both behavior and the nature of stimuli and rewards also contribute to the development of such tendencies."
Two important points: 1) the subjects were not asked to abstain from masturbation or sex - only porn, and 2) the subjects were not compulsive porn users or addicts. The findings clearly demonstrate that Internet porn is a unique and powerful supernormal stimulus, capable of altering what researchers though was an innate characteristic. From the study:
"Internet pornography is a sexual reward that contributes to delay discounting differently than other natural rewards do, even when use is not compulsive or addictive. This research makes an important contribution, demonstrating that the effect goes beyond temporary arousal."
As thousands of rebooters have revealed, Internet porn use can affect much more than one's sexuality. From the study's conclusion:
"Pornography consumption may provide immediate sexual gratification but can have implications that transcend and affect other domains of a person’s life, especially relationships. It is therefore important to treat pornography as a unique stimulus in reward, impulsivity, and addiction studies and to apply this accordingly in individual as well as relational treatment."
The study also contains a useful discussion of the role of dopamine and cue-driven behavior. In addition, it provides a lot of research on why sexual cues and internet cues (constant novelty) require special consideration. Evolutionarily, the survival advantage of delay discounting for sexual stimuli would be to urge mammals to ‘‘get while the getting is good," thus successfully passing on their genes.
As the researchers said,
"Pornography use in itself may be a harmless activity but, given what we know about the reward system and the primacy of sex as a natural reward and visceral stimulus, it also has the potential to become compulsive or addictive."
The researchers predicted porn consumption would increase impulsivity for 3 reasons:
- Sexual urges can be extremely powerful, and have been related to impulsivity in past research
- Pornography consumption is a simple replacement for real encounters, can become habitual, and can the condition user to instant gratification
- Constant novelty of the internet can lead to repeated stimulation and habituation (decreased responsiveness, driving an need for more stimulation)
Finally, as most of the subjects were still in adolescence, there is a brief discussion of how adolescents may be uniquely vulnerable to internet porn's effects.
"With regard to the current sample of college students (median ages of 19 and 20), it is important to be aware that, biologically, adolescence extends to approximately age 25. Adolescents show more reward sensitivity and less aversion to overconsumption, making them more susceptible to addiction."
J Sex Res. 2015 Aug 25:1-12.
Internet pornography is a multi-billion-dollar industry that has grown increasingly accessible. Delay discounting involves devaluing larger, later rewards in favor of smaller, more immediate rewards. The constant novelty and primacy of sexual stimuli as particularly strong natural rewards make Internet pornography a unique activator of the brain's reward system, thereby having implications for decision-making processes. Based on theoretical studies of evolutionary psychology and neuroeconomics, two studies tested the hypothesis that consuming Internet pornography would relate to higher rates of delay discounting.
Study 1 used a longitudinal design. Participants completed a pornography use questionnaire and a delay discounting task at Time 1 and then again four weeks later. Participants reporting higher initial pornography use demonstrated a higher delay discounting rate at Time 2, controlling for initial delay discounting.
Study 2 tested for causality with an experimental design. Participants were randomly assigned to abstain from either their favorite food or pornography for three weeks. Participants who abstained from pornography use demonstrated lower delay discounting than participants who abstained from their favorite food. The finding suggests that Internet pornography is a sexual reward that contributes to delay discounting differently than other natural rewards. Theoretical and clinical implications of these studies are highlighted.