Babies are fearless when it comes to heights. That woozy, faint feeling only starts kicking in around month nine, when babies begin to recoil from the edge of a steep staircase or the drop-off of a changing table. Researchers writing in the journal Psychological Science wondered what changed, and they suspected it was the experience of moving around. ScienceDaily:
The researchers randomly assigned some babies to receive training in using a powered baby go-cart, providing them with locomotor experience, while other babies received no such training. Critically, none of the babies had begun to crawl.
The data revealed that infants who used the baby go-cart showed tell-tale increases in heart rate when confronted with the virtual drop-off, indicating that they were fearful; infants in the control condition did not show such increases.
So what’s going on in those go-cart riding babies that makes their hearts go all aflutter? The researchers think it’s a sudden lack of visual cues. The New Scientist writes:
This suggests that the act of propelling yourself around in space teaches the brain to become aware of information in the peripheral visual field and use it to correct balance, says Campos.
In other words, the world is steady and predictable, but once babies start moving around, they find that, sometimes, due to a drop, the visual world is no longer there. It’s disorienting and scary. The information they need to move confidently around the world just isn’t available.
The New Scientist puts this finding into terms non-babies can relate to:
The finding might also explain why a passenger looking out of a plane window experiences no vertigo, while the same person in a transparent “bubble cockpit” helicopter can be reduced to a gibbering mess. When you look out of a plane window the information in your peripheral vision is relatively fixed, whereas in a bubble cockpit there is far more happening.
More from Smithsonian.com: