"Two by Two" or "Why One is Not Enough"

A lot of Cog Sci research is focused on figuring out the basic mechanisms of sensation and perception, mostly because we need to understand the basics before we can make real claims about more abstract, interesting, human-type cognitive activities. This is all just to preface the next bit.

As far as I can tell, our bodies know that 'two are better than one', especially when it comes to perceiving and navigating through space. Think about it. At an obvious and general level, we have two feet to walk and two hands to manipulate things. On a more cognitive neuroscience-y level, we have two eyes that see slightly different views of the world (allowing us to perceive depth more easily), and we have two ears that hear two different sound profiles of the world (allowing us to locate the sources of sounds). This all makes sense.


Here's where things get strange. We have a nose. We have two nostrils. Recently, researchers at Berkeley found that this is a big deal (in terms of spatial perception). Despite the fact that humans don't depend on olfaction (smell) in the same way that other mammals do (see dogs, cats, rats, etc), these researchers found that humans are perfectly capable of following a scent trail (see image #1, one the left is a dog following a pheasants scent trail; on the right is one of the subjects in the study).



Not only that, but they used a 'nose prism' (row f in image #2, don't ask) that allowed the researchers to control whether the participants were breathing air from one or two airstreams. Turns out that participants breathing two different airstreams (which means that each nostril got slightly different air/scent inputs) were both faster and more accurate in their scent-tracking than those who only smelt air from a single stream! I think that it is crazy that we (our brains) are capable of detecting differences between our nostrils (that's like 5mm, nothing!).