How Babies Learn to Fear Heights

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As any parent knows, babies aren't born with a fear of heights.
In fact, infants can act frighteningly bold around the edge of a
bed or a changing table.

But at around 9 months, babies become more wary of such
drop-offs. New research suggests infants build an avoidance of
heights once they get more experience crawling and navigating the
world on their own.

In one of their experiments, a group of scientists from the
University of California, Berkeley, and Doshisha University in
Kyoto studied babies that had
not yet begun to crawl. Over the course of 15 days, some of the
infants were trained to use a motorized baby go-cart that they
could control. [ 9
Myths About Babies Debunked ]

After this period, the researchers watched how the babies reacted
when they were held over a glass-covered edge. The infants who
had experience with the go-cart got skittish around this virtual
cliff. Their heart rates sped up, while the heart rates of the
babies without the driving lessons remained steady, the
scientists found.

The researchers also tested how these babies reacted to a
so-called moving room, an enclosure where the walls move
backwards and make whoever is inside feel like he or she is
moving forward. The babies who had learned how to use a go-cart
were more upset by this illusion.

In another part of the experiment, the researchers tested babies
who had already started to crawl. The ones who were most upset by
the moving room were also more afraid to crawl over a
glass-covered virtual edge, even as their mothers encouraged them
from the other side, as
video from the experiment shows.

This finding suggests that as infants gain locomotor experience
(in this case, crawling or navigating a go-cart), they come to
rely more on visual information to help them move though an
environment. The results also indicate that a
fear of heights is not likely a hard-wired developmental
change, but rather a shift that depends on experience, the
researchers say.

An avoidance of heights has an obvious advantage: It keeps
infants from falling and getting injured. So why doesn't it kick
in before babies start
crawling ?

"One major benefit of such a delay is that infants are more prone
to explore their environment and the movement possibilities
afforded by that environment when they are less concerned about
the consequences of their actions," the researchers write in the
journal Psychological Science.

This lack of fear helps them develop movement strategies and
learn how to navigate different types of surfaces, the scientists
say.

"Paradoxically, a tendency to explore risky situations may be one
of the driving forces behind skill development," the researchers
add.