Big Think sits down with the Professor Emeritus at the University of Delaware.

Marvin Zuckerman: Marvin Zuckerman, Professor Emeritus, from the University of Delaware.

Question: What is sensory deprivation?

Marvin Zuckerman: Sensory deprivation is where you put people in dark, sound-proof rooms, or water tanks. People were becoming aware that we needed sensation stimulation, variation stimulation almost as much as we need food and water and so forth. It’s a basic need. Deprivation of this kind of stimulation led to some very uncomfortable states.

So we asked, is there a personality trait that some people need more stimulation or more variety or intensity of stimulation than others? That’s when we developed our first sensation-seeking scale. Subsequently that expanded and became the main focus of my research. We were surprised by how many things were affected by this trait, sensation-seeking. Then we got interested in the biological basis, the genetic biological basis and here again, we had some very interesting findings pointing to the fact that this is a very fundamental trait with biological roots.

Question: How much of the sensation-seeking trait is determined genetically?

Marvin Zuckerman: Well this is determined from twin studies called Biometrics of Behavior Genetics actually. Using these twin studies we initially found that roughly 60% inheritability. In heritability is the proportion of the variance in a trait that is determined by genetics. We discovered there was 60% -- which is very high for a personality trait which generally runs between 30% and 50%. So, 60% is high for a personality trait. Well, it’s higher for intelligence and some other traits. This was established not only using twins raised together but twins raised apart showing that it wasn’t due to the fact of sharing a stimulating environment let’s say. There’s an environmental aspect of the remaining 40%, **** error of measurement, but some of it is due to environment. But it’s not the shared; what we called the shared environment, shared in the family. It’s due to the non-shared environment which means your friends, peers or your unique life experiences that you don’t share with other people in your family.

Question: Was sensation-seeking a factor in human evolution?

Marvin Zuckerman: Well we can surmise that particularly since a particular gene has been found to be related to sensation-seeking, a dopamine receptor gene. So that means it’s been there a long time. Well, actually they estimate though that it’s been – not all evolution maybe 50,000-100,000 years old in our species, this particular gene but there may be genes that are older even. But you see this in other – the point is, you see what I call emalogues of sensation-seeking behavior in other species. In fact, a lot of my work is compared sensation-seeking expressions exploration approach to novelty in other species. And I explored to the extent that do they have the same biological roots in humans and in other species. So, in that sense we look at evolution – we have a modern test of evolution when you can find something that exists in humans in earlier species, particularly primates ****, but also even in rats, when you can find this and it’s linked to the same biological indicators in both humans and other animals. That indicates it has an evolutionary history rather it’s more than merely an analogy. Well this looks like what we do. But it’s more than that, it’s the fact that it looks like sensation-seeking and has the same biological roots.

Question: Does the presence of this behavior vary across ages?

Marvin Zuckerman: I would say the age differences are somewhat larger if you’re looking at the extremes. I would say like of about sixty-sixty-five a male would have half the sensation-seeking score that he had when he was in his late-teens and early-twenties. So that's pretty much of a decline. The male-female differences are constant across age, but perhaps not as large. I want to talk about sex differences in traits. We’re always talking about a lot of overlap or talking about population differences. People always say, “I know someone who’s female, but has a very high sensation-seeking.” Of course, there’s variation within both genders. Just the overall population difference is different.

Question: Are men more prone to possess the sensation-seeking trait?

Marvin Zuckerman: Well we find that it’s genetic in both, but males are almost always higher on the general trait and particularly on those subscales that deal with impulsivity. We call them disinhibition, for instance is one scale. And another is Thrill and Adventure Seeking. These are things men are particularly high on. These are things that also peek in adolescence and decline with age. So that’s an interesting thing because sensation-seeking also peaks in adolescence, it higher in men then women, peeks in adolescence, late-adolescence and declines with age.

Question: How does modern society repress the sensation-seeking gene?

Marvin Zuckerman: Well in the past, sensation-seeking was found in just the struggle for survival. Hunting I would imagine. The successful hunters were men who enjoyed it even at the risk of hunting large mammals. Mammoths and things like that. War has always been fighting among men, and still is related to sensation-seeking. But in modern western society where there is no war, most people find their sensation in other kids of activities. For instance, thrill and adventure seeking. Ordinary sports don’t provide much of that, exception sports like skydiving and hang gliding and white water rafting and things like that provide the sensation thrill and adventure seeking for a minority of people who engage in them. Your modern average man for instance finds his sensation-seeking in the way he drives his car. We find the high sensation seekers are more risky drivers. They drive at higher speeds, young males have more accidents, they tailgate; they use their cars for thrill and adventure seeking, and aggression. Sensation-seeking isn’t all thrill and adventure seeking. Sensation-seeking has outlets through other aspects through sex for instance. Which again is the reason for it’s survival that was involved in seeking a mate. And some men, and women, need a lot of variety in their sexual outlets and behavior and others don’t need that much variety and therefore are more monogamous. So that's one area. Drugs, drinking, partying, these are all outlets for sensation seekers involving different kinds of risks, but involving risk nevertheless.

Question: Are risk-seekers more prone to becoming addicted to drugs?

Marvin Zuckerman: Well, there are four types of risk taking which form the core you might say, smoking, drinking, drugs and sex. Now you can see three of those are substance abuses, and they act through the central nervous system. They act on centers in the central nervous system that give intrinsic pleasure. Particularly stimulant drugs like cocaine. They provide pleasure. They provide the kick that activities provide, like sex provides, for the sensation seeker. They are all correlated because they are all aspects of intensity seeking sensation and the novelty too. There’s a difference, for instance, in drug users between those who are high sensation seekers and those that are low. I found this out when I was treating drug abusers. The low sensation – well the average sensation-seeking drug abuser tries one drug which he enjoys particularly and sticks to it. The low’s try many different drugs. So, invariably they get into odd drugs like LSD that affect their minds as well as they provide unusual sensations as well as arousal, the low’s stay away from those drugs.

I remember once sitting around in a discussion in this drug abusing community and they were relating their drug experiences. One of them was a high sensation-seeking LSD user and he was talking about that he – and another one was shaking his head. And they asked him, “Joe, why are you – what do you think of this?” He says, “Man, that’s crazy.” Now this is a heroin abuser understand. “Why would anyone fool with that? That’s dangerous. It’ll fuck with your mind, you know?” He just couldn’t understand it, he just used heroin which initially provides some highs, but eventually it’s used because of the lows because you need it to stay feeling normal

Question: What is a specific link between high sensation-seeking and drug use?

Marvin Zuckerman: You find for instance that high sensation seekers – there are not many men who love war and combat, but there are a few, there are some who really find that exciting and will re-volunteer simply because they are bored with military life outside of combat. And there are various substances which are interesting as they stimulate the same sensors that are stimulated by intense and novel external stimulation. Drugs do that more directly, particularly drugs like cocaine.

Question: Is there a link between sensation-seeking and creativity?

Marvin Zuckerman: There is, particularly for one type of sensation-seeking, we call it experience seeking, seeking sensation through the mind and the senses for one type of experience seeking. High sensation seekers are more prone to engage in divergent thinking. They don’t think in the conventional ways. They tend to think along unconventional lines. And this is a part of creativity. Creativity is the ability to think and do things in a way that haven’t been done before. Part of novelty-seeking, you might say. So, in a sense, they tend to be more creative if they have ability to be creative. When we think of creativity, we think of abilities. Many of the people on the streets who are drug dealers are very creative. They are creative criminally. They think of new ways of doing the things, you know. But we don’t call that creativity, even though it is creativity. So it depends on what – if you have the ability to pursue your divergent thinking along the lines that will result in the production of something whether it’s business, art or science. You have the ability plus the sensation-seeking that makes you more creative in what you’re doing.

Question: Is there a link between sensation-seeking and anxiety?

Marvin Zuckerman: Well actually there is no relationship between sensation-seeking and neuroticism or anxiety. You might think that’s funny because they seem to lack fear, but the kind of fear they lack is fear of physical harm. Neuroticism anxiety is based on a different kind of fear, mostly social fear. They don’t differ on that; they’re independent. That’s an independent trait, neuroticism. So you find that many high sensation seekers are high as are low and most are average in neuroticism. It’s that physical fear that they differ on. The high sensation seekers tend to; first of all, see things as less risky than lows. If you ask them, even something they’ve never tried before, if you say, “How risky is this?” The highs are going to say it’s riskier. Then when they do it, they demonstrate less fear arousal because fear arousal makes something unpleasant. Those who are not that high in sensation-seeking, they may try it under peer pressure or something and then they find that even though no harm comes to them they find it an unpleasant experience because of the fear that it arouses. So they’ll never do it again. They say, “Okay, I’ve done that, I’ll know not to go do it again.”

Whereas, the highs value that kind of whatever fear they felt just gave a little kick to the experience and made it even more pleasurable, oddly enough. Because it was fearful, they overcame the fear and they experienced pleasure.

Question: Why are violent films more prominent today than in the past?

Marvin Zuckerman: Well, there’s a thing that happens with sensation-seeking. Habituation. Habituation is a basic law of learning, the lowest organisms. When you expose them to something repeatedly, over and over, they respond less to it. They are less aroused by it even though initially it was arousing when they get used to it then nothing particular happens they get less aroused. Now in the violence around sex this occurs too. Habituation. So, what was initially very arousing, let’s say in sex, you know the honeymoon, with time becomes still pleasurable, but less arousing and that’s why the high sensation seekers have to look for new sources of arousal. Now this occurs in films too. You start out with simple horror films and the high sensation seekers say, “Eh, that’s fine.” But they get bored by it and so when they are allowed to legally and recently society has loosened the laws about the depiction of violence and sex in the media. So, they keep pushing it to the extreme because that as high sensation seekers become habituated, they become bored with it and they need something more. They go to something that’s more exciting.

Same think in thrill seekers. Skydivers, they find that very initially very exciting and that’s why they like it. Then they become used to it and they have to do new things like they do the stunting and things like this, and group things, and then that become boring. Some of them even go on to even more dangerous ones like base jumping. You know what base jumping is. Base jumping is; you jump not from an airplane, but from a cliff or a building even, or something where you have very little time to open your parachute. Timing is very important and a lot more people die with that sort of parachuting. Okay. And yet, why do they do it? Because it’s really more exciting due to the fact that they have less time, it’s not that they do it because they’ve become habituated to less arousing form, but for them now less arousing form them. So that’s why everything tends to escalate in the sensation seekers from lesser expression to sometimes more dangerous expressions.

Question: What happens when one is deprived on sensation?

Marvin Zuckerman: Well, what was happening psychologically, they’d just become bored and restless if they were high sensation seekers. If they were low sensation seekers, they were fairly comfortable and once they had high anxiety trait – we measured how much they would move around. We could actually measure their restlessness. At the beginning, the first three hours, there was not difference, but as time went on the highs being more and more restless, twitching, turning on the bed. They began to sing to themselves even though they knew they weren’t supposed to speak or to simulate themselves. They began to stimulate themselves. So, that was the expression of it.

If you go a long period – what’s happening in the brain is, over longer periods of time, even over shorter periods is that the brain waves are slowing down. The basic arousal in the brain, the alpha waves are getting slower. Okay. And that, for most people, is unpleasant. To go below your optimal level of arousal for any prolonged period of time becomes unpleasant. And if you give them any kind of stimulation in sensory deprivation, even looking at meaningless blotches of color they will avidly press a bar to do that. They are being deprived of something, variety and variety of stimulation and when you deprive people of that, that is very aversive to them. It’s one of the ways of torture actually of putting people – it’s not just the social and sensory deprivation when you put someone you know. It’s the sensory deprivation. You put people in an environment they might not be under sensory deprivation, but if nothing is varying in their sensory environment, it is becoming increasing aversive.

Question: Is this form of torture more human than others?

Marvin Zuckerman: No, it’s not humane, and it’s not – solitary confinement it’s called in prison. It’s a punishment when they put them in solitary confinement, which usually sensory deprivation as well because even if there is light in the cell, there’s no variation. Nothing is changing, mo one to talk to. Part of social isolation is the lack of social stimulation. So, over time, it is very torturous. It’s a mental torture of a sort that could be very effective. The torturer is often – they usually isolate their prisoners before they begin interrogating them because then they respond – they have at tendency to respond to any stimulation, even interrogation is more primed by the sensory deprivation

Question: How did you become interested in sensation-seeking?

Marvin Zuckerman: Well, as I say, it came out of a natural course of my research in sensory deprivation which is the opposite of sensation-seeking. But I must admit, perhaps I was – at that time in my life I looked at people – friends who were high sensation seekers and I looked at them once and I kind of – I used them as kind of a prototype when I was designing this trait. But what are the things they do? What do they like? Now since now we have other ways once we had designed it. But you have to have the idea – was a new idea for a trait which no one was really measuring at that time. Okay? So to get my idea, I looked around to what people were doing and the first form of this test we were depending on saying, “Would you like to do this?” Like, would you like to do skydiving? Because we assume most people aren’t doing it, but the mere liking, or wanting, or the thought that they would like to do it is something that characterized a higher sensation seeker.

Whereas a lower sensation seeker would say, “No, that’s crazy. Why would I want to do that? That’s dangerous.” What people might like to do, **** the first items for our thrill and adventure seeking sub scale. Then we asked, “What about one of the other aspects? And we looked at sex, drugs. And we asked questions, would you like to do this, would you like to do that? Or, in the case of sex, what do you like to do? Or what are your attitudes toward it? Are they permissive attitude? So those were the sort of things that we looked at. So, that’s how I got the initial items. We have different kinds of items now that don’t include content, just the need for excitement.

Question: Were you a high sensation seeker at a young age?

Marvin Zuckerman: Well, I would say to be a publishing professor teaching, you can’t be too high because if you’re too high, you’re out doing other things. You’re not doing research and writing. But I would say that I was higher than average – then the average professor. Now recently that became a mote point when they discovered this gene, the Dopamine 4 Receptor Gene. I was in England. By this time I was getting on in age, it was my last sabbatical, but I had the chance – I was in the genetics lab there and I had the chance to have my own DNA examined for the presence of this particular gene, or the form of the gene. So, I did and I found I had the long form of the gene, which is the type associated with sensation-seeking, but as I explained to my colleagues there, my sensation-seeking by the time I was 60, my sensation-seeking was confined to riding the top of the double-decker bus in London because age – you may have the gene for something but it’s expression is affected by other biological factors related to age. Like the rise in MAO with age which reduces sensation-seeking.

Recorded on: October 22, 2009