Optical illusions are a fun and creative way to demonstrate that you can’t always trust your senses. Optical illusions can be thought of as a way your brain tries to make sense of what you see by changing how you perceive the stimulus. They are a perfectly natural phenomenon and don’t necessarily reflect your eye health or brain health. There are three main categories that most optical illusions fall in — literal, physiological, and cognitive. In today’s blog here at Poudre Valley Eyecare in Fort Collins, we briefly explore the three main types of optical illusions and their characteristics.


Worried about your eye health? Schedule your appointment here at Poudre Valley Eyecare in Fort Collins today.



Literal optical illusions can be described as an image within another image. For example, the most common literal optical illusion is the image of two faces facing one another. Both are just shadows with no detailed characteristics on a white background. Upon further inspection, many people start to see a white goblet instead of the two people facing one another. The shapes of the faces also create the shape of the goblet in the center.


Here are some examples of literal optical illusions!


Physiological images are much different than literal optical illusions. Physiological optical illusions are often thought of as afterimages. Many of you may have experience with staring at an unmoving stimulus for so long that when you look away or close your eyes, you can still see the afterimage even with your eyes closed. Additionally, perceiving an unmoving or static image as moving and changing also falls into the category of physiological optical illusions. The theory behind this type of optical illusion is that the eyes and brain are getting excessive stimuli or are receiving conflicting stimuli that your brain is trying to make sense of.


Here are some examples of physiological optical illusions!


Afterimages and other optical illusions can sometimes cause eye strain. A little eye strain is normal, however, if your eye strain doesn’t go away or worsens, then you should consult an eye health professional right away. 


Cognitive illusions are a stimulus that uses your pre-existing knowledge about how the world works and uses that to fool our brains. This is often done through the use of lighting, shading, angles, and other visual cues that our eyes and brains use to perceive the world around us. The information that our senses are giving us and our existing knowledge of the world can conflict, confusing our unconscious brain. This causes our brain to focus on one version of the stimulus that makes sense — whether it is accurate or not. Once we understand the illusion, however, we can control the illusion and reverse its effects in our minds.


Here are a few examples of cognitive optical illusions!

Poudre Valley Eyecare

Here at Poudre Valley Eyecare in Fort Collins, we are eye health professionals with years of experience working with a variety of people with all manner of different eye problems. If your eyes are sore from too many optical illusions, you are experiencing changes in vision, vision loss, or simply haven’t been to the eye doctor in a while, contact us at Poudre Valley Eyecare in Fort Collins to schedule your eye care appointment!