This is Scientific Americans 60 Second Science. I'm Jason Goldman. Got a minute?

Both of us were in the lab when we just saw a spider and I'm really afraid of them.

So I started to scream for her to come and pick it up because she's not afraid of them.

Ben Guryan University of the Negev Psychologist Tolly Labevich talking about herself and a colleague.

And she said, but it's small, how come you are afraid of it?

And I said, no, it's huge.

She said, it's small, I said, it's huge.

And we started arguing and this is why we started this study to see who was right.

Labovitch does not ordinarily study spiders, but this spider encounter made her curious about how the human

brain understands magnitude.

What are the factors that influence our estimation of how big or how small something is.

And does Fear play a role?

So she and her colleagues did an experiment, in which participants had to say how big a spider

in a photo was on a scale from house fly to goat.

And the subjects who were afraid of spiders consistently rated the Arachniz as

larger than did the nonphobic participants.

But the spiderphobes did not miscalculate the size of butterflies or

birds, nor did they see wasps as larger than life, even though wasps can be dangerous.

The estimation error was spider-specific. It seems our emotions drive us to experience

the same world in very different ways. The results are in the journal Biological Psychology.

Now we can ask the question of what causes what? So is it the fear of spiders

that makes you see them is larger or first you see them is larger for some reason and then because of it you start being afraid of them.

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