The failure of the independence axiom, once again

It seems that the mere presence of a salad on a fast food menu makes people more likely to order french fries.

Here is more.


Similarly, the presence of family-friendly fare on pay-per-view TV in hotel rooms probably increases the probability that the hotel guest will proceed to watch an adult film.

The local corner store also takes care to stock various useful items that rarely sell, even though they make nearly all of their profit from cigarettes, beer, soda, lottery tickets and maybe the occasional candy bar.

The seemingly superfluous items can be thought of as part of the decor or setting a certain ambiance, no less than piped in Muzak or colorful banners or other aspects of the shopping experience. People don't just care about what they're buying, they also care about what kind of a place they're buying it in. The researchers are rediscovering something that retailers have instinctively known all along.

I think you mean this is a violation of IIA (Independence of Irrelevant Alternatives). The Independence axiom, used in expected utility theory, is something else.

Since preferences are not restricted by assumption, it doesn't violate IIA for the decision maker's definition of "irrelevant".

I'll have the blueberry pie.

Seems there's another possibility that should be examined: that the presence of an unsatisfyng alternative on a menu serves to reinforce one's preference for richer or more satisfying tastes. As in, "rabbit food? No, gimme something tasty! Put on a side of fries!"

This could be especially the case if the salad is just described so as to conjure up wilted greens, maybe a bricklet of pasty pink tomato, and a bunch of acidic glop with red bits poured over it. That's about all I get in even fairly high class institutional settings that I find myself in. (E.g., "first class" meals in the air.)

Indifferently prepared burgers taste like meat. Indifferent fries supply lots of hot oil and salt. But indifferent salad (what students might reasonably expect) tastes like it got shoveled out of the scraps in the produce truck.

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