In 1910, a series of experiments were conducted that have come to be known as the Perky Experiments. They have achieved an almost mythical status, but the result shave been repeated and verified. In the experiments a subject was asked to look at a white wall, and unbeknownst to them a faint image just above the normal threshold of visibility, was back projected in soft focus onto the wall. Subjects to asked to visualise in their mind an image on the wall. Throughout the experience a wide range of subjects from young children to professional scientists were shown a variety of images and each subject reported similar results. Every subject believed that they were imagining the image they saw and had no idea that they were in fact perceiving the image presented on the wall. Further experiments have since been conducted and verified the results and it was later refined by Segal in 1972. Nanay (2016, p138) describes the experiments conducted in the later version as follows:
“They (subjects) were asked to imagine the skyline of New York City (For example) while, unbeknownst to them, they were gazing at an image of a red tomato (For example). The result was that they imagined New York City at sunset (Segal 1972). In other words, in the modified Perky experiment, the imaginative episode of visualizing the New York City skyline is sensitive to external, unrelated influences.”
What the experiment appears to show is that there is not a clear delineation between perception and imagination (though this interpretation is somewhat contentious). This could mean a lot of things in the way we perceive reality, but one common and likely interpretation is that the imagination creates representative images of what we perceive in our mind, and this in turn also constitutes perception. The fundamental difference between reality and an imaginative construction of the mind then is that reality simply allows us to generate a much more vivid projection that we are able to cognitively identify as “real”. We do not experience reality directly on this view, rather we perceive it through a range of senses and experiences and imagine a representation of it based on the information presented to us. This also explains why we often experience that same thing differently to others, because we each imagine a different reality. In a very real sense we each live in our own version of reality and perceive it as best we can through constant exploration and experimentation.
In any case this is one of those creepy experiments that makes you really contemplate reality and your understanding of the world around you.