Not the new truth serum.

Magnetic Pulses to the Brain Make it Impossible to Lie: Study

Zapping the brain with magnets makes it IMPOSSIBLE to lie, claim scientists

Holy crap! Hold on to your civil liberties...get your tin foil hat.... Something really exciting must be going on in neuroscience.

Right?

So it turns out that these articles refer to the following study:

Here, participants were shown red and blue circles and asked to name the color of the circle. At will, the participant could choose to lie or tell the truth about the color of the circle. However, while they were performing this task, repeated transcranial magnetic stimulation (rTMS) was applied to one of four brain areas (right or left dorsolateral prefrontal cortex (DLPFC), or right or left parietal cortex (PC)). TMS produces a transient magnetic field that produces electrical activity in the brain. As it is causing the brain to have different firing behavior, TMS allows researchers to gain insight into how certain brain areas cause behavior. Previously, the dorsolateral prefrontal cortex has been implicated in generated lies. Here, the authors sought to assess whether this area has a causal role in deciding whether or not to tell a lie. Here, the parietal cortex served as a control area as it is not generally implicated in the generation of lies.

So, is TMS to DLPFC the new truth serum? Here, I've re-plotted their results:

When TMS was applied to the left DFPFC (compared with the left PC), participants were less likely to choose to tell the truth whereas they were slightly more likely to be truthful when stimulation was applied to the right DLPFC. As you can see from the graph, the effect, although significant, is pretty tiny. The stimulation changes your propensity to lie or truth-tell about 5% in either direction. This cannot be farther from the "impossible to lie" headlines.

Interesting? Yes. Useful for law enforcement? Probably not.

Karton I, & Bachmann T (2011). Effect of prefrontal transcranial magnetic stimulation on spontaneous truth-telling. Behavioural brain research, 225 (1), 209-14 PMID: 21807030

Carrots and sticks, sure but...

The theory of hyperbolic discounting asserts that the farther in the future a consequence (positive or negative), the less it matters to us when compared to an immediate consequence. This is why we abandon our diets in the face of a cupcake: the future hot body just pales in comparison to fatty, sugary goodness right now.

This is why putting clear economic incentives on habits can be so effective. Ian Ayers' Carrots and Sticks is an excellent book detailing how making behavioral contracts can be effective for smoking cessation, weight loss, etc.

So, I'm on board with the method. However, I don't quite understand this motivational structure for working out. Here, a gym membership costs more when you miss a workout. Maybe this is just me (I see my gym time as my favorite time of day), but missing a workout already costs you more because your monthly membership dues means that you're paying more per workout when you work out less.

Thoughts?

Is it time to question a lack of free will?

In the early 1980s, psychologist Benjamin Libet conducted a relatively simple experiment that critically shaped the way we think about free-will. Participants sat facing a clock, keeping a finger on a button, and were instructed to lift the finger whenever they pleased, remembering the clock time corresponding to the time when they decided to move the finger. All the while, EEG was being recorded. Libet found that 300-500 msec before participants moved (and about 150 msec before reporting that they decided to move), that a strong negative signal was found in the EEG waveforms. If the brain "knows" you are going to move before you do, do you really have conscious control over your own behavior?

The Libet experiment has been replicated, if not uncontroversial among philosophers. However, a new paper in Psychological Science questions whether the readiness potential is an artifact of observing a moving clock.

In the new study, Jeff Miller and colleagues presented participants with two decision-making conditions: a clock condition, similar to that of Libet, and a condition without the clock. If the time between the decision and the movement is constant, then one can look at the EEG from the time to move, with or without the clock. The authors found that participants in the clock condition showed the readiness potential, but the participants in the no-clock condition did not, suggesting that the act of monitoring the clock modulated the EEG signal, not the preparation for making a decision.

I think that this study is innovative as we need new methods to study the time course of decision making. I do think it asks more questions than it answers, though. For example, there are differences between the clock and no-clock groups that go beyond the presence of a clock: being asked to keep a time in mind provides a load to working memory that the no-clock participants did not have.

Is it time to give up on Libet? I'm not so sure. Is it time to reconsider with new methods? Absolutely!

Miller J, Shepherdson P, & Trevena J (2010). Effects of Clock Monitoring on Electroencephalographic Activity: Is Unconscious Movement Initiation an Artifact of the Clock? Psychological science : a journal of the American Psychological Society / APS PMID: 21123855

Book review: Addiction: A Disorder of Choice by Gene Heyman

I was apprehensive about reading this book. I was worried that it was going to be a hyper-conservative and moralizing tome. What I found instead was a provocative and well-researched book that I highly recommend to anyone interested in addiction, public policy or psychiatry.

As is clear from the book’s title, Heyman asserts that the dominant paradigm of drug addiction (that it is a “chronic and relapsing brain disease”) is not correct, and that by viewing addiction as the result of a series of willful actions, we have a better understanding of the course of drug addiction and its treatment.

Why is this view controversial? It strikes at the heart of the paradoxical way that we view drugs and drug addiction in the modern US. Heyman explains: “The reasoning behind this view is that if addiction is a disease, then science will soon find an effective treatment for it, as had been the case for many other diseases, but if that addiction is a matter of choice, then the appropriate response is punishment… The core assumption of this viewpoint is that there are but two possible responses to addiction: treatment or punishment”. As a good liberal, I was uncomfortable starting the book because I was worried that Heyman would be blaming the victims of addiction, and potentially creating policy that would take away treatment options, leaving them worse off.

Heyman remains unfortunately agnostic on what ought to be done about drug abuse, but focuses instead on the science and history of drug abuse and drug policy. Here are his central arguments for addiction being a choice:

The same drugs have different effects on people that depend on cultural context

Across time, culture and place, the reactions to the same drug are markedly different. If drug abuse were a biological reflex, this would not be the case. Of course, some of the “cultural contexts” listed by Heyman (smoking versus injecting heroin, for example) can dramatically influence the metabolism of the drug, which is a biological context that can influence receptor binding, etc.

The more interesting piece of this argument was that studying only those in treatment for drug addiction biases many studies of drug addicts. These people have higher co-morbidity with other mental illnesses and are more likely to relapse. For most people, a drug habit runs a natural course, beginning in a person’s late teens to early twenties and ending by age 30. Heyman profiles the majority population of invisible “successful addicts” who start and end drug-taking behavior as free choices.

The right motivations get just about anyone to quit

When people are given enough motivation, nearly all can quit taking drugs. 85% of drug addicted doctors and airline pilots faced with the possibility of passing all future random drug tests or losing their jobs will quit taking drugs. “Change your incentives, change your behavior, change your brain”.

The genetic basis for addiction is not compelling.

Heyman uses religiosity and twin studies to prove this point. Religion is a learned and voluntary behavior, and twins tend to have similar degrees of religiosity. However, the religiosity data only show a 0.3-0.4 correlation between even identical twins, so I agree with Heyman that the argument is a little weak.

The book misses a great opportunity to go into the neuroscience of addiction, as strengthening neural circuits associated with habit, and down-regulating neurotransmitter systems affected by the drugs could be very potent reasons why drug taking is so difficult to stop.

Near the end of the book is an argument of choice behavior, largely based on the very cool research of Drazen Prelec and colleagues. While it takes Heyman a while to set up the background, it is worth following as it has a lot of explanatory power for habitual behavior of all kinds, not just drug addictions. In brief, as the negative consequences of taking drugs accumulate slowly while the positive feeling of taking drugs is immediate (albeit diminishing over time), it takes a long-term perspective to see that drug-taking is a losing prospect in the long-term. The same goes with any bad habit: while just one cupcake will not cause you to gain 20 pounds, the habit of eating cupcakes over time will accumulate those 20 pounds. It takes a strong future orientation to see that the immediate deliciousness of the cupcake is not worth the long-term metabolic cost of the cupcake. Heyman refines his argument here by pointing out that while it is silly to say that someone would choose to be an addict, one becomes an addict from the accumulation of choices. “The point is that one day of heroin does not mean addiction, just as eating desert once does not make one fat. Of course as the days accumulate, the characteristics of addiction emerge, and as the deserts accumulate, fat cells get bigger”

One disappointment is the frequent straw-man argument along the lines of “It is not likely that anyone ever referred to recovery from obsessive compulsive disorder or schizophrenia as ‘going cold turkey’”.  These arguments seem to appeal to the emotions behind addiction rather than the science. Also, cognitive behavioral therapy, which involves the willful changing of one’s beliefs and behaviors, is an effective strategy for combatting other mental illnesses such as OCD, only showing how nuanced the idea of will in mental illness really is.

Subtle influences on choice

Like most people, I like to think that my choices are a result of clear, rational thought. However, our decision processes are far more heuristic than we admit. Two new articles on choice bear this out:

Mantonakis and colleagues studied how the order of items presented to us affects our preferences and choices. In their experiment, several wines were presented to participants to taste and rate. Although participants were told that all wines were from the same varietal (e.g. pinot grigio), in reality, all of the samples were from the exact same wine! If preference and ratings were rational, then the average rating a wine receives by subjects should be the same regardless of whether it was tasted first or last. However, they found that the first wine tasted by participants was preferred over wines in other serial positions, a finding known as the primacy effect.

In the second paper, Krajbich and colleagues modeled decision choices made by subjects between two pieces of junk food. Krajbick brought junk-food-loving, hungry participants into the lab, and asked them to rate how desirable 70 different junk foods are to them. Then, in front of an eye tracker, they were presented with pairs of pictures of these food packages and asked to decide which they would prefer to eat after the experiment. Unsurprisingly, people are quicker to decide when the value of the two choices is very different. However, when the decision is more difficult, participants tended to choose the item they looked at more.

Both of these studies are laboratory demonstrations of things advertisers seems to have known for a while: to get you to buy their product, getting you to look at it early and often might be enough to get you to buy it.

Mantonakis, A., Rodero, P., Lesschaeve, I., & Hastie, R. (2009). Order in Choice: Effects of Serial Position on Preferences Psychological Science, 20 (11), 1309-1312 DOI: 10.1111/j.1467-9280.2009.02453.x

Krajbich I, Armel C, & Rangel A (2010). Visual fixations and the computation and comparison of value in simple choice. Nature neuroscience, 13 (10), 1292-8 PMID: 20835253

The self-control meta-game

Previously, I wrote about the use of neuroscience in the courtroom as a defense for criminal actions. I asserted that these arguments hold water only insofar as they can demonstrate a clear causal connection between the brain injury and the criminal behavior, and that it was not possible for the defendant to control himself in the presence of such a brain injury.

Although I am a card-carrying pinko, I am enjoying the new book by Gene Heyman, Addiction: A Disorder of Choice. (A longer review post forthcoming once I finish the book). Heyman challenges the view that addiction is a compulsory chronic and relapsing condition. By illustrating historical, cultural and individual differences in drug reactions, he shows that drug dependence can be overcome with will (and massive amounts of effort and motivation). This brings us right back to the question we left off with last time: under what circumstances can we reasonably expect a person to demonstrate self-control?

A common model of self-control posits that exhibiting self-control is an effortful, resource-consuming process. According to this model, a person has a set amount of self-control that can be exhibited before failure and/or “recharge”. A common source of evidence for this model is the fact that exhibiting self-control appears to consume a good deal of glucose. (Of course, this is a very interesting idea for those whose self-control is being directed towards dieting!) Another measure of self-control failure are mistakes on a Stroop test.

A compelling new study examines the limitations of the resource-limitation model of self-control. A first experiment demonstrated that people who do not agree with the resource-limitation model made fewer mistakes on the Stroop test following a cognitively demanding task than did those who professed beliefs in the model. Even stronger was a second experiment where manipulation of participants’ beliefs in the model had the same effects. Of course, like many things in psychology, William James was here before us when he stated “The greatest discovery of my generation is that a human being can alter his life by altering his attitudes”.

Job V, Dweck CS, & Walton GM (2010). Ego Depletion--Is It All in Your Head?: Implicit Theories About Willpower Affect Self-Regulation. Psychological science : a journal of the American Psychological Society / APS PMID: 20876879

Did my brain make me do it?

Our first case is from a 40-year old man who developed a new and intense interest in child pornography.  His sexuality also generally increased, and he found himself frequenting prostitutes even though he never had before.  He was ashamed of his behavior and went to lengths to hide it, and could communicate that it was morally wrong.  However, he then began making sexual advances on his pre-pubescent step-daughter and spoke of raping his landlady.  He was removed from his home, but failed a 12 step sexual addiction program as he could not restrain himself from soliciting sexual favors from the staff and fellow group members.  As he failed the program, he was sentenced to prison, but developed debilitating headaches and balance problems shortly before admission.  An MRI revealed a large tumor in his orbitofrontal lobe, an area associated with self control, executive function and the regulation of social behavior.  Following surgical removal of the tumor, the man was able to successfully complete the sexual addition course, successfully moved back in with his family and no longer had pedophilic or other deviant urges.

Consider, then our second case: the 1992 trial of Herbert Weinstein, a 65-year-old advertising executive who was charged with strangling his wife to death and then, in an effort to make the murder look like a suicide, throwing her body out the window of their Manhattan apartment.  At his neuropsychiatric evaluation, it was found that Mr. Weinstein had a small, subarachnoid cyst in his brain. The defense moved to use this cyst as evidence of Mr. Weinstein’s inability to control, or be responsible for, his behavior. The cyst in Weinstein’s brain has never been linked to mental illness or violent behavior. After a contentious pre-trial hearing about using this evidence, Mr. Weinstein accepted a plea bargain.

Are both of these men equally responsible for their own behavior?

A central tenet of neuroscience is that all behavior is caused by the brain. This sounds simple enough, but given our long intellectual history of separating the mind from brain, we hold very dear to the idea of an “I”, separate from the 3 pounds of electrical meat that is our brain, calling the shots. After all, “I” feel like “I” make decisions that shape my life. If “I” wasn’t responsible for these decisions, if the decisions instead came from the electrical meat, which is determined by the laws of physics, then how is it that “I” decided to wear a blue shirt instead of the red one? More troubling, if “I” am just my brain, and my brain is malfunctioning, am “I” still responsible for my behavior?

People are remarkably consistent in their moral judgments. Therefore, with some confidence, I can predict that you feel that the man from case 1 is less responsible for his behavior than Mr. Weinstein from case 2.  Is this gut-level feeling rational? After all, both men had damage to their brains, and their brains govern their behavior.

The problem with many cases of “my brain made me do it” arguments is that the association between a brain injury and a behavioral problem is not causal evidence that the injury caused the behavior. Another way of saying this is that “correlation does not imply causation”. We are quick to call B.S. on associations that don’t seem to have plausible causal connections: although drowning is associated with ice cream consumption, we do not guess that ice cream causes drowning. In the criminal realm, we are also likely to see through a Twinkie defense, even if “neuro-babble” makes for a more compelling case.

However, in the case of the first man, we are able to establish a causal connection between his brain injury and his bad behavior: he had “normal” behavior (presumably) before and after the tumor. Unfortunately, we cannot surgically repair most malfunctioning brains, so most connections between behavior and brain are speculative.

Beyond the problem of causality is the problem of will. How can we establish that someone absolutely cannot control his behavior? People can exhibit a certain degree of regulation over even autonomic functions using biofeedback or certain styles of meditation. In the lab, feedback from fMRI has been used to train subjects to willfully activate and de-activate a region involved in the perception of pain. However, it is incredibly difficult to willfully change most behaviors. It takes many days of consistent effort to form new habits. Many ex-smokers report that the physical withdrawal from nicotine was much easier to deal with than the reprogramming of one’s automatic response to grab a cigarette in various contexts. Although the politics of how we frame addiction is a larger topic for another post, suffice it to say that there is no consistent agreement what behaviors we expect people to be able to control, and those we don’t.

So, did my brain make me do it? Well, yes, of course it caused my behavior. Am I to be held responsible for this behavior? Given the above difficulties, I have to agree with Michael Gazzaniga who states that this question is to be left to the legal scholar and not the neuroscientist.