Departures from Consciousness: Q&A with Psychology Professor Peter Tse

We all lapse out of consciousness every night when we sleep, but what happens when we depart from consciousness during our waking hours? This week, the Mirror interviewed professor of psychological and brain sciences Peter Tse to learn more about the basis of consciousness and how people depart from it every day.

Could you explain the science behind how our minds form consciousness?

PT: Nobody knows the general basis of consciousness exactly, but we do know some things about it. We know, for example, that for visual consciousness, if I knock out the motion processing area, then people can’t see motion. If I knock out another area, they can’t see color, and if I knock out another area, they can’t see shape. We know it at that level, but we don’t have any general solution for the neural basis of consciousness.

The majority of processing in your brain is not conscious, and a lot goes into the construction of your consciousness — for example, when photons get to your retina. Your conscious experience of the world that’s based upon what hits your retina is not at the same time as it hitting your retina; it happens later, approximately a quarter second later. There’s a delay between retinal activation, or events in the world, and our conscious experience of them, and the reason for that is because our conscious experience has to reflect what’s going on in the world. The problem is what hits the retina is a pattern of pixel-level activations that don’t contain any information about 3-D shape or causation, so in the quarter of a second between retinal activation and your conscious experience of the world, there has to be all this processing that constructs a story about what’s happening in the world, based upon what happened at the retina.

Could you explain some of the science behind departures from consciousness, such as hallucinations, flashbacks, subconscious thoughts or daydreams?

PT: Let’s talk about the case of hallucinations. The case of hallucinations is, in a way, not exactly a departure from your normal consciousness as it is a hyper exaggeration of what goes on in normal consciousness. You might argue that even normal perception is analogous to something like a hallucination, in that it’s not of what’s happening at the retina; it’s a kind of story about what’s likely happening in the world, given what happens at the retina. You might say hallucinations are a departure from normal consciousness in the sense that you start constructing things that are not really there, whereas normal consciousness involves constructing events and experiences about what is presumably really there. It’s possible to hallucinate because the same constructive processes that create your normal consciousness can create wrong information.

How does daydreaming work, and how does it differ from hallucinations?

PT: A hallucination involves perceiving something that’s not really there. Daydreaming is a very different kind of departure, in that you’re departing attending to the outside world, and now you’re attending to an inner world, so daydreaming is more like internal virtual reality. For example, you might imagine who to invite for dinner tonight and imagine a table with food on it and putting people at the table and deciding which food goes to who. Daydreaming is not so much about what’s going on in the outside world; it’s about what could happen in the future or what did happen in the distant past. Both daydreaming and hallucinations are a departure from your normal consciousness, but they’re very different departures — in one, you start constructing events that are not really happening, and in the other, you’re constructing events that could happen.

Are there certain stimuli that might instigate someone to start daydreaming or hallucinating, and what might they be?

PT: There’s some very nice work by two scientists — Jonathan Schooler and Jonathan Smallwood — in which they gave people buzzers. The task was, anytime the buzzer went off, participants had to write down exactly what they were thinking, daydreaming or seeing. Based on that data, people spend half of their waking lives daydreaming. Even when they’re supposed to be fully engaged, like a pilot landing on a runway, even then, people will be daydreaming as if they’re on autopilot.

I think daydreaming is not triggered by a stimulus — it’s more triggered by disengaging from what you’re doing. Boredom might actually be a reason we start daydreaming, so when a task is easy for you, then your attention is freed up; it doesn’t have to be allocated to the outside world. If something happens in the real world, like a deer jumps in the road, suddenly your attention has to be jerked back to reality. A stimulus can bring you out of a daydream, but I don’t think there’s necessarily any stimulus that makes you daydream.

I would really put all these departures from consciousness in different categories. There are the ones involving shifting your attention from the outside world to the inner world, and that would include your imagination, dreaming and daydreaming, and there’s the one involved with hallucinations — where you’re seeing things that are really not there — and those can be drug-induced, induced by fever or other stimuli. In a way, we are all subject to visual illusions. I think visual illusions are really interesting because, in a way, visual illusions are mistakes, and you’re seeing something you know cannot be real, and those mistakes tell us about the neural processing that goes into the construction of our visual reality.

What makes some people more susceptible to daydreams while others can maintain concentration more easily?

PT: I don’t know if there’s a single factor. I do know that some people are more susceptible to hypnosis than others, and those people who are the most susceptible to hypnosis are often those who are best able to imagine themselves in imaginary worlds where they have a really rich fantasy life, so there might be a correlation between the kinds of departures you’re capable of and your makeup. Certainly, little children spend a lot of time in fantasy, and we call that pretend play, and fewer and fewer adults engage in it as we get older. We have to ask: why do children depart from everyday ordinary reality, in order to attend to this virtual reality of their own creation?

It might be adaptive because all mammals seem to play, but our kind of play is different because we have pretend play where we can pretend to be things that we’re not. For a baby tiger, it can pretend to pounce and pretend to be aggressive and pretend to be submissive, but it can’t pretend to be a dog. In humans, a little kid will stick his arms out and pretend to be an airplane. This kind of pretend play might be unique to our species, and it might be because we have the capacity to imagine things that are not the case and would never be the case, so we can be counterfactual whereas an animal cannot.

There’s a price we pay for that, which is probably various forms of madness where we imagine things that are in fact not the case. A schizophrenic may imagine, for example, that aliens are putting voices into his head, or he’s being controlled by thought-wave projecting satellites, which is seemingly kind of crazy, but it might be the price we pay for having our kinds of imagination.

Is there anything else you’d like to add?

PT: The ultimate departure from consciousness is death. I think the majority of scientists operate under the assumption that consciousness is realizing brain events, and when the brain dies, consciousness ceases. That’s a fundamental assumption of physicalism or materialism in science. Now, a lot of people with a religious perspective would challenge that and would argue that when the brain dies, the departure is not the sensation of consciousness but the departure of the soul from the body.

We talked about hallucinations, and I would imagine that there are some real puzzles in the kinds of hallucinations or experiences that people report having as they reach death, like out-of-body experiences or seeing light-filled tunnels. From my perspective as a physicalist, that could well be because visual cortical areas are no longer getting the oxygen they need, but an alternative view would be that is because you are in fact going down a tunnel as you leave your body. I don’t believe in that, but I can understand why some people would believe in it — the ultimate departure from our normal consciousness is the consciousness we have as we are dying.

This interview has been edited and condensed for clarity and length.