Epstein’s Dollar Bill and What it Doesn’t Prove About the Brain

I hate to pick on poor confused Robert Epstein again, but after thinking about it some more, I’d like to explain why an example in his foolish article doesn’t justify his claims.

Here I quote his example without the accompanying illustrations:







Now let me explain why Epstein’s example doesn’t even come close to proving what he thinks it does.

First, the average person is not very good at drawing. I am probably much, much worse than the average person in this respect. When I play “pictionary”, for example, people always laugh at my stick figures. Yet, given something to look at and copy, I can do a reasonable job of copying what I see. I, like many people, have trouble converting what I see “in my mind’s eye” to a piece of paper. So it is not at all surprising to me that the students Epstein asks to draw a dollar bill produce the results he displays. His silly experiment says nothing about the brain and what it “stores” at all!

Second, Epstein claims that the brain stores no representation of a dollar bill whatsoever. He is pretty unequivocal about this. So let me suggest another experiment that decisively refutes Epstein’s claim: instead of asking students to draw a dollar bill (an exercise which evidently is mostly about the artistic ability of students), instead give them five different “dollar bills”, four of which have been altered in some fairly obvious respect. For example, one might have a portrait of Jefferson instead of Washington, another might have the “1” in only two corners instead of all four corners, another might have the treasury seal in red instead of the typical green for a federal reserve note, etc. And one of the five is an ordinary bill. Now ask them to pick out which bills are real and which are not. To make it really precise, each student should get just one bill and not be able to see the bills of others.





  1. brucegee1962 says

    What Epstein really seems to be trying to prove here is that the brain is not a digital camera. It memorizes things in terms of systems and relationships, not a bitmap.

  2. shallit says

    I think we have to be cautious about universal claims about how the brain represents things, especially when we are still struggling to understand it. Consider, for example, prodigious feats of memory, like the people who memorize pi to many digits (I think the current record is 70,000). Or the people who can multiply 20-digit numbers in their heads. Do you really think these things are achieved by “systems and relationships” alone? Personally, I doubt it.

    • mk says

      “Do you really think these things are achieved by “systems and relationships” alone?”

      Of course.

      “Personally, I doubt it.”


  3. tcmc says

    The cruder drawing in Epstein’s article is a representation of a one dollar bill. The second part of the experiment in which the subject creates an image from the actual bill neither adds to or detracts from the fact.

    • shallit says

      Yes, that’s so, tcmc. But I would add even more is true: the ability of subjects to draw a dollar bill says little about how many bits of representation about the dollar bill they store. Simple information theory, combined with a more elaborate experiment of the type I described, would suffice to estimate how many bits the average person has. Epstein doesn’t seem to understand this at all.

  4. smrnda says

    Your proposed experiment reminds me of some studies in cognitive psychology when they try to figure out what characteristics of things people use to categorize, particularly with children as they begin to understand categories. An example is kids will quickly get that wheels are on vehicles, and not animals.

    Speaking of computers, machine learning often involves (simple explanation) training a computer to categorize things based on features rather than ‘storing’ any complete representation in memory. In fact, to be useful in recognizing items which are not all identical, a computer has to recognize them by key features instead of matching them to an example. So Epstein seems a bit out of date on machine intelligence if he thinks they recognize dollar bills by matching them to a stored picture. If that was the case, than a program for recognizing bills would be easily thwarted simply by defacing George’s face. Epstein should try the following experiment : take a crisp, clean one dollar bill, draw sunglasses on George Washington, and see if a machine will still accept his currency.

Leave a Reply
