Eyes’ movements reveal what’s on your mind
You generally feel like you’re in charge of your eyes. If you have an interest in something, your brain aims your eyes at it and you observe it, right? It turns out that our eyes are are involved in a lot more hunting, scanning, and maybe even processing than we’re consciously aware of. These activities help our vision, thinking and even memory, sometimes before we’re even realized it.
When you enter a room, your eyes will dart around, making quick scans of everything they can until something catches your focus. Even then, your eyes will not rest completely on a single subject, continuing to sweep the environment in tiny movements called saccades. These help stablize your vision as you move around (as compared to the method employed by say, a pigeon.) They also help you gather more detail than your lenses would otherwise be able to, which are assembled into a single image in your brain without conscious effort.
Cognition and conceptualization
When your eyes aren’t sweeping or focusing on the environment around you, your gaze sometimes gets appropriated by your thought processes. Thinking about differences between numbers seems to trigger a sort of linear, spatial model in most people’s minds, arranged in ascending order from your left field of vision. When thinking of larger number, your eyes will often look up and to the right, and vice versa for smaller numbers. This may be hard-wired to a degree, as even baby chicks show some similar behaviors when ‘counting.’
If you’re thinking of something less abstract than a number line, like a visual memory, your gaze may actually be crucial for proper recollection. When recounting a visual memory, your eyes will often try to reproduce the same saccades they made in the original event. If prevented from doing so (say, because you are actively keeping them focused on a single point,) your recollection of the memory will be less successful.
Finally, if this weren’t enough to give away your next hand at poker, your pupils are ready to give up your thoughts as well. When something excites you, either positively or negatively, your pupils will dilate. For example, they’ll widen slightly the moment you change your mind and are ready to try something new for the first time, often before you actually state any of these intentions out loud.
So perhaps our eyes aren’t simply observational organs. Rather than only take information in, they seem to actually share a lot of the mind’s inner workings with the outside world as well.
Source: How your eyes betray your thoughts by Mo Costandi, The Gaurdian