One important philosophical question is whether humans can ever see and, therefore, interact with the world objectively. The rabbit hole can run so deep that it can make one question the very nature of reality. Researchers have now brought this age-old inquiry out of limbo and used techniques from cognitive science to offer some form closure. Their investigation suggests that ‘no’, humans are not really equipped to see things objectively.

Do you trust your eyes?

Led by Chaz Firestone, an assistant professor of Psychological and Brain Sciences and Director of the Hopkins Perception & Mind Laboratory, the team of researchers employed a series of experiments meant to challenge the participants’ sense of reality.

On a computer screen, participants were shown pairs of round, three-dimensional objects (coins) that were tilted away from them, distorting the perspective of the objects in question into ovals and ellipses. Over the course of nine sessions, one of the coins was always a true oval, while the other was a circle. The participants simply had to pick which coin they thought was the true oval.

That seems easy enough, but time and time again the participants became confused and, when presented with the tilted circular coins, they hesitated.

The significant delay in time response was consistent across all experiments, regardless of whether the coins were still or moving, had different shapes, and whether they were shown on a computer screen or physically shown right in front of the subjects.

“This question about the influence of one’s own perspective on perception is one philosophers have been discussing for centuries,” Firestone said in a statement, alluding to the works of the likes of John Locke or David Hume, who wondered centuries ago whether it is ever truly possible to separate the way an object truly is (a circle) from how it appears (an ellipse).

The findings, however, suggest that vision is not only influenced by physics — how light bounces off objects, hits the retina, which then sends signals that are processed into sight by specialized areas of the brain — but also by assumptions and knowledge of the world gained throughout our lifetimes.

“Our subjective approach to the world stays with us. Even when we try to perceive the world the way it really is, we can’t completely discard our perspective,” said Jorge Morales, a post-doctoral fellow at Johns Hopkins and lead-author of the new study, which was published in the Proceedings of the National Academy of Sciences.

“I think it was quite memorable to see the reaction of our colleagues around the world when we presented the results of our studies at different academic conferences. Some of the people whose views we criticize in the paper were truly perplexed by our stimuli and our results, but their openness to engage with us and our experiments was extremely rewarding. Similarly rewarding was the appreciation we received from some of our colleagues with respect to the harmonious mix between science and philosophy that our studies tried to achieve. For example, after presenting our results at the annual meeting of the European Society for Philosophy and Psychology, Asifa Majid—professor at the University of York and chair of the Cognitive Science Society—kindly described our experiments as “elegant” and as a “highlight of the marriage of philosophy and psychology” during the conference,” Morales told ZME Science.

This is just the first of several experiments that the researchers are working on using approaches from psychology and neuroscience to test ideas from philosophy related to subjectivity, Morales told me in an email. For instance, these projects will investigate how stereotypes affect perception and how people perceive objects that aren’t really there, in other words how they perceive the absence of things.

“We think that the study should be important for the public for at least three reasons. First, it provides an empirical answer to a centuries-old question. While the philosophical and scientific details may be complex, I think many people in the public may have asked themselves similar questions about the nature of what we see. We invite readers to hold a coin head on in front of a friend or family member, tilt it, and ask them if the coin looks round or oval to them (clarifying that the question is about what the coin looks like as opposed to what shape they know it has). They might be surprised by the strong—often contrasting—intuitions that people have around this problem. Our study provides a novel empirical answer to this often-irreconcilable intuitions: A rotated coin looks both circular and oval! Second, it’s a nice example of the importance of keep asking foundational questions. We surmise that the mainstream assumption in cognitive science holds that perception is mostly just objective. By borrowing concerns from the philosophical literature, we are able to revise this assumption. Finally, we think our work is a nice example of the importance of interdisciplinary work. Beyond our particular research question, our study is a reminder of how philosophy can ask very precise and important questions and how cognitive science can offer powerful methods to put those ideas to empirical test,” Morales and Firestone told ZME science.