Back in 1991, Mark Knopfler sang"Sex and money are my major kicksNow twenty years later a team of French neuroscientists have followed up on this observation with a neuroimaging study: The Architecture of Reward Value Coding in the Human Orbitofrontal Cortex.
Get me in a fight I like the dirty tricks"
Sescousse et al note that people like erotic stimuli, i.e. porn, and they also like money. However, there's a difference: porn is, probably, a more "primitive" kind of rewarding stimulus, given that naked people have been around for as long as there have been people, whereas money is a recent invention.
The orbitofrontal cortex (OFC) is known to respond to all kinds of rewarding stimuli, but it's been suggested that the more primitive the reward, the more likely it is to activate the evolutionarily older posterior part of the OFC, whereas abstract stimuli, like money, activate more anterior parts of that area.
While this makes intuitive sense, it's never been directly tested. So Sescousse et al took 18 heterosexual guys, put them in an fMRI scanner, showed them porn, and gave them money. Specifically:
Two categories (high and low intensity) of erotic pictures and monetary gains were used. Nudity being the main criteria driving the reward value of erotic stimuli, we separated them into a “low intensity” group displaying women in underwear or bathing suits and a “high intensity” group displaying naked women in an inviting posture. Each erotic picture was presented only once to avoid habituation. A similar element of surprise was introduced for the monetary rewards by randomly varying the amounts at stake: the low amounts were €1-3 and the high amounts were €10-12.You've gotta love neuroscience. Although the authors declined to provide any samples of the stimuli used.
Anyway, what happened?As hypothesized, monetary rewards specifically recruited the anterior lateral OFC ... In contrast, erotic rewards elicited activity specifically in the posterior part of the lateral OFC straddling [fnaar fnaar] the posterior and lateral orbital gyri. These results demonstrate a double dissociation between monetary/erotic rewards and the anterior/posterior OFC ... Among erotic-specific areas, a large cluster was also present in the medial OFC, encompassing the medial orbital gyrus, the straight [how appropriate] gyrus, and the most ventral part of the superior frontal gyrus. [immature emphasis mine]In other words, the posterior-primitive, anterior-abstract relationship did seem to hold, at least if you accept that money is more abstract than porn. (Many other areas were activated by both kinds of rewards, such as the ventral striatum, but these were less interesting as they've been identified in many previous studies.)
Overall, this is a good study, and a nice example of hypothesis-testing using fMRI, which is to be preferred to just putting people in a scanner and seeing which parts of the brain light up in a purely exploratory manner...
Sescousse G, Redouté J, & Dreher JC (2010). The architecture of reward value coding in the human orbitofrontal cortex. The Journal of neuroscience : the official journal of the Society for Neuroscience, 30 (39), 13095-104 PMID: 20881127
8 comments:
The research showed pictures of partially clad and naked women to subjects. Were the same pictures shown to both men and women? Were erotic photos of men also shown to all subjects? Were homosexuality variables factored into the study?
And, were subjects selected within one age group or across a variety of ages? I'd like to know the responses of subjects when compared across different ages.
Intuitively it doesn't seem that every decade of a human life would contain the same responses to the stimuli presented.
For the results to be meaningful I think we need more of a breakdown of results in terms of subject response. "Men" and "women" categories are too broad.
Joanna, the paper states that they used only male heterosexual males and subsequently the erotic stimuli was of females.
Participants were aged at an average of 24 with a s.d. of 3.3 years. This is probably the result of convenience sampling and the fact that, at least at this point, age does not play into the hypothesis.
Overall, the methodology used seems acceptable considering the hypothesis and the conclusions made.
There is actually a methodological difficulty with doing this across genders: while the type of pictures men find rewarding are predictable, the same does not hold for females.
At least, that's what piloting at one of my university's labs showed. It would mean that more female subjects would be necessary in order to pick out especially rewarding pictures.
Although it may be harder to predict which images women will find rewarding, showing the same images to women or male images to heterosexual males would still help to control for the possibility that activity in a given region is simply in response to recognition of a "naked people" category.
I'm also not so sure money is less primitive. Well, money is, but what about a more broad category of "resources?"
Granted, I guess I should admit that I haven't actually read the paper and this isn't really an area I know too much about. So maybe the authors considered these already in the discussion.
Probably because money/reward/barter has been associated with sex gratification from the earliest time known to Man.
Learned habits associate themselves with primitive instincts to achieve satisfaction in ways that are short.
It is to be noted prostitution is the oldest trade.
Study would have been more rounded if females were also studied.
Money and sex? Money is a symbol for status, a value of rank.
How many women has not get married 'upwards' on the social ranking list, often with elderly men.
Diamonds are a girls best friend.
Maybe men work so hard just to be able to give women what they want, value. Maybe it should be wiser to give women their value right from the beginning.
But what does this study exactly explain? That different areas of the brain respond to money and sex. What's so insightful about that?
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