Emotional parts of our brains respond much more strongly to the sight of an animal than to anything else in our environment, a new study shows.
When we see an animal, our amygdala – an area associated with fear and reward – responds much more quickly and strongly than to, say, a landmark or an inanimate object. Scientists think this response may date back all the way to our earliest four-legged ancestors.
As the journal Nature Neuroscience reports, a team led by Florian Morman at the California Institute of Technology gathered a group of 41 volunteers. Thanks to some epilepsy therapies that involve inserting electrodes into specific brain areas, the team were able to precisely monitor the electrical activation patterns of individual neurons in several regions.
The scientists kept track of electrical activity in the each patient’s amygdala, hippocampus, and endorhinal cortex, as the volunteers looked at images of animals, people, landmarks, and objects. It turns out that the right amygdala, in particular, responds very strongly to the sight of an animal.
This asymmetry is intriguing, because it may reflect some deep-seated biases that reach far back into our evolutionary history:
Hints of [this asymmetry] appear in animals’ tendency to favor one eye, and thus one side of their brain, when scanning for food or predators. That behavior has been found in every class of vertebrates, from mammals to fish.
It’s also worth noting that these responses in the amygdala seem to happen independently of any subjective fear emotion – in other words, although the amygdala is involved in processing fear, it seems to handle images of animals whether or not they’re involved in a fear response. This may suggest that the process of sorting images into “types” may be even older than our emotions themselves:
This selectivity appeared to be independent of emotional valence or arousal and may reflect the importance that animals held throughout our evolutionary past.
Morman also points out that it’ll be interesting to find out exactly where in the nervous system this right-side bias happens – it could be somewhere in the amygdala itself, or it might begin even further toward the outlying ranges of the optic tract.
It’ll also be interesting to see if these findings have anything to do with the infamous Cat Proximity Effect. I’d better confirm this effect by seeking out some adorable kitties – you know, for science.