After faulting economists for ignoring marketing, Geoffrey Miller harshly attacks mainstream marketing for ignoring what he calls the “Central Six” – IQ plus the Big Five personality traits.  At first, you might think he’s merely telling marketers, “Here’s something useful you’ve overlooked”:

Surprisingly, most marketers have no idea how well the Central Six can
predict consumer behavior.  The typical consumer behavior textbook
includes a large section devoted to individual differences, but no
discussion of general intelligence and the Big Five factors.  Rather,
the focus is on diverse “factors” that may influence consumer decision
making: wealth, time, knowledge, attitudes, values, self-concepts, and
motivations.  The fact that the Central Six efficiently predict
individual variation across all these factors remains unknown or
ignored… Marketers likewise pay attention to “demographic variables” – age, sex, ethnicity, socioeconomic status – without taking into account their correlations with the Central Six.

But on closer look, Miller position seems to be, “Knowledge of the Central Six makes mainstream marketing obsolete”:

So, most current research on marketing and consumer behavior relies on a chaotic grab bag of outdated theories and unreliable findings.  The potent effects of general intelligence are hidden behind its causal effects, empirical correlates, and politically correct euphemisms: education, class, socioeconomic status, consumer knowledge, “cognitive resources,” and “cultural capital.” Often, marketers think they are studying the effects of class, race, or religion on consumer decision making when they are actually studying the effects of intelligence, which shows different average scores, for whatever reasons, across different classes, races, and religions.  The potent effects of the Big Five are likewise hidden behind their correlates and euphemisms: attitudes, motivations, self-concept, values, lifestyle, culture.  Here, marketers think they are studying the effects of sex, age, or political beliefs, when they are actually studying the effects of openness, agreeableness, stability, or extraversion, which also show different average scores across males and females, young and old, liberals and conservatives.

Miller makes little effort to charitably explain the mainstream marketing position.  But even if we take his caricature as fact, mainstream marketing seems far more predictively useful than the Central Six.  Consider a few random examples:

Hannah Montana.  Mainstream marketers would presumably say that age and sex are the key predictors of interest.  What do the Central Six have to add?  Maybe a little – I suspect that tween girls higher in IQ and Openness would spend fewer dollars and hours on Hannah Montana.  But how many 38-year-old men of any IQ and personality type voluntarily watch her show or listen to her music?

Strollers.  Mainstream marketers with their “chaotic grab bag of outdated theories and unreliable findings” might foolishly suggest that people buy strollers if and only if they have very young children.  What do the Central Six have to add?  I guess Miller might respond that high IQ customers buy Peg-Peregos (I finished assembling one today, that’s the ticket!).  Still, only mainstream marketing explains why people are in the market for a stroller in the first place.

iPods.  Mainstream marketers would probably claim that age
matters a lot.  Maybe the Central Six could add in IQ and Openness, but
they’d probably be marginal.  If you’re 80 years old, you probably don’t
own an iPod, even if your IQ and Openness are in the 95th percentile.

Morton’s.  Mainstream marketers would say that people who eat at Morton’s have high income.  What’s Miller alternative?  That Morton’s is really a restaurant for people with high IQs?  Come on – there are a lot more people of average IQ and high income at Morton’s than people with average income and high IQ.

Even Miller’s favorite example – bumper stickers – doesn’t have his back.  Sure, there are lots of IQ and personality-themed bumper stickers.  But aren’t there far more political bumper stickers?  Miller might object that political ideologies are mere proxies for personality.  But when you look at the empirics, that’s just not true.  Personality tells you something about ideology, but most of the variation remains unexplained.  Bottom line: If a car has an Obama bumper sticker, you know the driver’s party with at least 90% probability.  But even if I gave you a .5 SD margin of error, how confidently could you predict the driver’s IQ or personality?

I suppose it’s conceivable that I’m cherry picking my examples to make Miller lose the Mainstream Marketing – Central Six Cage Match.  So here’s my challenge: Pick a random object in plain sight.  (Anything displayed in an open browser window counts).  What would mainstream marketing say about this object?  What would Miller say?  Which approach explains more about consumer behavior?