62 JOURNAL OF ECONOMIC EDUCATION
In response to this assignment, students in my principles course have tackled a
host of fascinating questions. The following are some recent examples:
Why do the keypad buttons on drive-up automatic teller machines have Braille
dots? (Bill Tjoa)
An interesting question! Visually impaired persons can do many remarkable
things, but they cannot drive automobiles on public roadways. Keypads at drive-
up machines have Braille dots, Mr. Tjoa reasoned, because once the keypad
molds have been manufactured, the cost of producing buttons with dots is no
higher than the cost of producing smooth ones. Making both types would require
separate molds and separate batches of inventory. If the patrons of drive-up
machines found buttons with Braille dots harder to use, these extra costs might be
worth bearing. But because the dots pose no difficulty for sighted users, Mr. Tjoa
concluded the best solution is to produce only keypads with dots.
Is this the right answer? After Ben Bernanke and I described Mr. Tjoa’s exam-
ple in our principles text (Frank and Bernanke 2003), we received an e-mail
pointing out that the suggested explanation, although plausible, was wrong—that
the Braille dots on drive-up ATM keypads were in fact a consequence of a Federal
regulation requiring them. Perhaps, but so what? For the purposes of the eco-
nomic naturalist writing assignment, all that matters is that the question posed be
interesting and that the proposed answer to it rest on plausible economic reason-
ing. On both counts, Mr. Tjoa’s response to the assignment clearly succeeded.
Yes, it is important to remind students that the additional step of testing a hypoth-
esis would need to be carried out before feeling confident enough to act on it. But
that is a step for another time and place.
Why do brides spend so much money on wedding dresses, whereas grooms
often rent cheap tuxedos, even though grooms could potentially wear their tuxe-
dos on many other occasions and brides will never wear their dresses again?
(Jennifer Dulski)
This is my all-time favorite economic naturalist question. In attempting to answer
it, Ms. Dulski began with the assumption that distinctive attire matters more for
women than for men on important social occasions. This might strike many as a
heroic assumption, but evolutionary biologists tell us that in largely monogamous
species, such as humans, distinctive appearance may indeed be more important for
women than for men. Precisely the opposite pattern is observed in species in which
dominant males take many mates. In those species, bright coloration and other dis-
tinctive features are more likely to be found on males than on females. Ms. Dulski
reasoned that if men need not wear distinctive clothing on special occasions, a
rental company could serve their fashion needs at relatively modest prices. Thus, by
focusing on only a few variants of the standard men’s tuxedo, a company could
maintain a sufficiently large inventory to accommodate clients of a wide variety of
sizes at rental prices that average roughly one-quarter of the garment’s purchase
price. If the goal were to appear in distinctive attire, however, it would be necessary
to hold an inventory in which numerous different styles were available in all differ-
ent sizes. Because this would require an inventory possibly dozens of times larger
than the corresponding tuxedo inventory to serve a given volume of rentals, a rental