Written by Emily Nagoski, Ph.D.
I was inspired by a RadioLab story from years ago (though I only just heard it) about, among a great deal else, the relationship between cognitive load and impulse control. Starting at minute six there's a story about how rational effort is finite and when it's being used up by a cognitive task, you decrease your ability to avoid doing irrational things.
Briefly, if you're in the middle of a high-demand cognitive task and someone puts both cake and fruit in front of you, you're more likely to choose the cake than if you were in the middle of a low-demand cognitive task. it seems the brain power used up by the cognitive task (in this case remembering either seven numbers or two numbers) takes away power from your ability not to do something bad for you.
What they don't tell you on the radio show is that this study also looked at what happens to decision-making when your options are right there in front of you, as opposed to being symbolically in front of you, (in this case chocolate cake and fruit salad versus pictures of chocolate cake and fruit salad). The difference between high cognitive demand and low cognitive demand disappears when someone puts pictures of cake and fruit in front of you, rather than the cake and fruit itself.
The difference also disappears if you're a "prudent" consumer, impervious to candy at the grocery store check out, as opposed to an "impulsive" consumer. Impulsives are people who describe themselves as impulsive, careless, easily tempted.
Conclusion: those with a proneness to impulsivity, presented with a real-world binary choice, will be increasingly likely to choose the tasty-but-bad-for-you choice as their cognitive load increases. It looks like a zero-sum game for them.
As a sex nerd, I hear these things and think, "Well if that happens with food, does it happen with sex too? And what does this imply about sex research?"
The vast majority of psycho-physiological sex research is done by investigating what happens to a subject's body while they watch sexually explicit films or look at pictures of naked women. Indeed, the sex researcher listserv I'm on spends a great deal of time trying to find the best possible video stimuli. So, taking into account the difference between food and pictures of food on decision-making, what's the difference between pictures or videos of sex and real life sex, like a beloved partner? Just exactly how depleted does a stimulus need to be before we're no longer getting a clear picture of how someone's real-life sexual response works?
And to what extent ought we to be sorting experiment participants by their proneness to sexual risk taking or impulsivity? We can do that pretty well by assessing their SIS and SES, which is known to correlate with risk behavior and sexual compulsivity. Should all psycho-physiological and survey research take such variables into account? How important are individual differences in figuring out how sex really works?
I've had the same thought about research on women's sexuality. If a survey or psycho-physiological study doesn't control for phase of menstrual cycle, a flag goes up in my brain and I have to wonder how their results might be different if they sorted their participants by menstrual phase.