A couple years ago, Aaron Swartz blogged about what he called the "percentage fallacy":

There’s one bit of irrationality that seems like it ought to be in behavioral economics introduction but mysteriously isn’t. For lack of a better term, let’s call it the percentage fallacy. The idea is simple:

One day I find I need a blender. I see a particularly nice one at the store for $40, so I purchase it and head home. But on the way home, I see the exact same blender on sale at a different store for $20. Now I feel ripped off, so I drive back to the first store, return the blender, drive back to the second store, and buy it for $20.

The next day I find I need a laptop. I see a particularly nice one at the store for $2500, so I purchase it and head home. But on the way home, I see the exact same laptop for $2480. “Pff, well, it’s only $20,” I say, and continue home with the original laptop.

I’m sure all of you have done something similar — maybe the issue wasn’t having to return something, but spending more time looking for a cheaper model, or fiddling with coupons and rebates, or buying something of inferior quality. But the basic point is consistent: we’ll do things to save 50% that we’d never do to save 1%.

He recently followed up with a speculation that this may explain some irrational behaviour normally attributed to hyperbolic discounting:

In a famous experiment, some people are asked to choose between $100 today or $120 tomorrow. Many choose the first. Meanwhile, some people are asked to choose between $100 sixty days from now or $120 sixty-one days from now. Almost everyone choose the laster. The puzzle is this: why are people willing to sacrifice $20 to avoid waiting a day right now but not in the future?

The standard explanation is hyperbolic discounting: humans tend to weigh immediate effects much more strongly than distant ones. But I think the actual psychological effect at work here is just the percentage fallacy. If I ask for the money now, I may have to wait 60 seconds. But if I get it tomorrow I have to wait 143900% more. By contrast, waiting 61 days is only 1.6% worse than waiting 6 days. Why not wait an extra 2% when you get 16% more money for it?

Has anyone done a test confirming the percentage fallacy? A good test would be to show people treat the $100 vs. $120 tradeoff as equivalent to the $1000 to $1200 tradeoff.

Is this a real thing? Is there any such research? Is there existing evidence that does especially support the usual hyperbolic discounting explanation over this?

I propose the following title keywords for Discussion posts, to be included as I did with [META] in this one.

• META: Posts about LW, in general.
• DRAFT: Drafts of posts that may be promoted to the main LW, posted for comments and criticism.
• POLL: Polls and (essay question–type) surveys on whatever topics seem to merit that format.
• LINK: Discussions centered primarily around a linked webpage.
• HELP: Posts requesting help with some question or problem.
• QUICK: The same sort of content (with respect to topic and structure and style) that you'd post to main LW, but smaller and quicker, perhaps.

Feel free to propose others, debate the merit of the ones I've suggested, tell me that the whole thing is a stupid idea, etc.

This is not meant to replace the actual Tags system, which is good for arbitrarily tagging posts by topic. I see this as a way to allow us to quickly scan through the list of Discussions and know what general type of content to expect from each item. I don't expect that absolutely everything will need one of these keywords, but many/most of the things that have been posted in Discussion so far seem to be categorizable along these lines. And I don't intend by this to encourage specific types of content (e.g. if we get more polls as Discussion posts now as a result of having a [POLL] keyword, then it is not working correctly), I only suggest that it may be useful for organizing the things people are already using this section for.