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stimulus. After just one pairing of the shock with one of the fear-

relevant stimuli, people showed fear when the snake or spider was

shown without the shock, while it took more pairings of the shock

and the flower, mushroom, or geometric object for fear to be

aroused by these fear-irrelevant stimuli alone. People also stayed

afraid of the snake or spider, while fear faded over time in response

to the flower, mushroom, or geometric object.*

Of course we are afraid of snakes and spiders in our current envi-

ronment, so is it really evolution that explains Ohman's results? If

this counterargument were true, then people should respond to

other dangerous objects in our current environment, such as guns

and electrical outlets, just as they do to spiders and snakes. But that

is not what Ohman found. It took just as long to condition fear to

guns and electrical outlets as it took to condition fear to flowers,

mushrooms, and geometric objects. Guns and electrical outlets have

not been around long enough for natural selection to have devel-

oped them into universal triggers.12

In his extraordinarily prescient book The Expression of the Emo-

tions in Man and Animals, Charles Darwin described an experiment

with a snake he performed more than a hundred years ago that fits

quite nicely with Ohman's recent work. "I put my face close to the

thick glass-plate in front of a puff-adder in the Zoological Gardens,

with the firm determination of not starting back if the snake struck

at me; but, as soon as the blow was struck, my resolution went for

nothing, and I jumped a yard or two backwards with astonishing

rapidity. My will and reason were powerless against the imagination

of a danger which had never been experienced."13

Darwin's experi-ence shows how rational thought cannot prevent a fearful response

to an innate fear theme, an issue to which I will return shortly.

It is not certain whether any such emotion themes operate as

active triggers prior to experience linking them to an emotional out-

come. Remember that in Ohman's research some experience was

required for the snake and spider to become fear triggers; they were

not frightening on initial exposure. It took only one association with*E. O. Wilson has discussed the fear of snakes in terms that are very consistent with what I have pre-

sented. Although he does not apply his framework specifically to emotion, it is very consistent with

what I am suggesting about the emotion data base. (See Consilience, Random House, 1998, especially

pages 136-40.)