Arianna Thoksakis is a doctoral student in the integrative neuroscience graduate program. She studies pareidolia in the hopes of understanding why it is that we see ghosts and shares her expertise here, just in time for Halloween.
What’s happening in our brains when we see a ghost?
There isn't one specific thing that happens in the brain when someone sees a ghost, because what we call a 'ghost sighting' can encompass several different perceptual experiences. The brain is constantly interpreting sensory information using both incoming signals and our expectations, memories and prior experiences. Under certain conditions, that process can produce an experience that someone interprets as supernatural.
One important factor is fear. Fear is a natural response that helps protect us from danger by making us more vigilant and aware of our surroundings. However, this heightened vigilance can also make us more likely to interpret ambiguous information as a potential threat. From an evolutionary perspective, this makes sense. Imagine being one of our prehistoric ancestors and encountering an unfamiliar shape in the darkness. If you mistakenly thought a harmless object was a predator and ran away, there might be little consequence. But if you failed to recognize an actual predator, the consequences could be deadly. In situations like these, being overly cautious could be more advantageous than overlooking a potential threat.
Context and expectations also play an important role. Our brains are constantly trying to make sense of the world using both incoming sensory information and what we already know or expect. They are great at filling in the gaps in sensory information. For instance, sometimes you might not hear a word in a sentence when talking with a friend, but because you know what the conversation is about and you're familiar with that person's speech patterns, you're able to figure out what they said without explicitly hearing it. In fact, our visual system is so good at filling in missing information that we ordinarily don't notice the blind spots in our own eyes! When we're in an unfamiliar or supposedly haunted environment, our expectations can influence how we interpret what we're seeing. If we're already frightened and anticipating a ghost, we may be more likely to interpret an ambiguous shadow as something supernatural. Additionally, humans are notoriously bad at seeing in the dark. Many reported ghost sightings occur in dimly lit environments where people may already expect to encounter something supernatural, whether that's because of stories they've heard or their own personal fears.
This brings us to pareidolia. Humans are particularly good at recognizing faces. In fact, we're so sensitive to face-like patterns that we sometimes perceive faces in completely ordinary objects, like electrical outlets or the front of a car. Research has shown that these illusory faces, called pareidolia, can rapidly engage parts of the visual system involved in processing real faces. However, exactly how the brain resolves the competing interpretations of an illusory face and its underlying object is still being investigated. Our perception may depend on factors such as how ambiguous the image is, what we're paying attention to and what we expect to see. When you combine these processes, it's easier to understand how someone might genuinely perceive something they interpret as a ghost. Their brain is doing what it normally does: trying to make sense of incomplete information, using the available sensory evidence alongside expectations and prior experience.
Consider this: someone walks into a dark room in an unfamiliar place. They might not have heard any scary stories about the location, but they're already on edge because they're in a new environment where they can't see very well. Then, they turn their head and see what looks like a face peering out at them from a dark corner. Quite a lot of people would run out of that room believing they'd seen a ghost staring back at them. However, a more likely explanation is that the shadows and patterns in the room happened to form something that looked enough like a face for the observer's visual system to interpret it as one.
How do you study this phenomenon?
Ultimately, my research is motivated by a larger question: why do people see ghosts? But to answer that, we first need to understand how the brain interprets ambiguous visual information. My dissertation focuses on one piece of that puzzle by investigating how we perceive faces in ordinary objects. Understanding these fundamental perceptual processes may eventually help us better explain experiences that people interpret as supernatural. Right now, I’m focused on understanding how our brains process pareidolia in the first place. I do this by showing people images of real faces, objects that appear to have faces (pareidolia), and ordinary objects. Then, I compare how the brain responds to these different types of images. I also investigate how our goals and attention influence the way we perceive pareidolia. For example, if someone is looking for a face, they may focus more on the face-like features of an object. However, if they're focused on identifying the object itself, they may pay more attention to its underlying structure. To investigate these processes, I use techniques such as EEG, eye-tracking, fMRI, behavioral experiments and brain stimulation to examine both neural activity and behavior when people perceive illusory faces.
Do you believe in ghosts? Have you ever seen a ghost?
I've had experiences that certainly felt paranormal, but as a neuroscientist, I also recognize that our perceptions aren't always an accurate reflection of what's happening around us. Just because an experience feels supernatural doesn't necessarily mean it is. As for whether I believe in ghosts, I think that's a more complicated question! Scientifically, we don't have compelling evidence that ghosts exist, and there are many fascinating neurological and psychological explanations for experiences that people interpret as paranormal. However, I also think there's something wonderful about the mystery of it all. I enjoy entertaining the possibility that there might be more to the world than we currently understand, while recognizing that possibility isn't the same thing as scientific evidence. I think there is something to be said for allowing a little bit of magic in our everyday lives, as long as we stay grounded in reality.
Are there any other common questions you get when you tell people about your research?
One of the most common responses I get is people sharing their own ghost stories with me! I've heard all kinds of fascinating experiences, and people are often very eager to tell me why they're convinced what they encountered was supernatural. Occasionally, I'll even wake up to an email from someone who wants to explain why my research is completely wrong! I think it just goes to show how personal these experiences can be for people and how strongly we can feel about the things we've perceived. It’s certainly made checking my email inbox interesting!
