Archive for the 'Neuroscience' Category

May 06 2019

Detecting Lies in the Brain

Published by under Neuroscience

It’s fairly common knowledge at this point that the polygraph test for detecting who is lying is not reliable enough to be used practically. Here is a good summary by the American Psychological Association (APA). The bottom line is that the entire idea of a lie-detector is problematic for various reasons. First, the underlying premises have not really emerged from psychological research, and has not been validated by research. The idea is that people will display physiological signs of stress when they are making an effort to be deceptive, or when confronted with incriminating information. However, the relationship between physiological signs and mental stress is too complex to develop any test. There is no universal feature of lying that can be detected.

The polygraph uses two basic techniques. The first is the control question test (CQT) – you ask questions of the person being examined, control questions that do not relate to the crime in question, and relevant questions related to the crime. The idea is that they will react more to the relevant than the control questions. The other method, the guilty knowledge test (GKT) is similar – mentioning random items along with one directly related to the crime may reveal guilty knowledge that only the perpetrator should know.

The idea sounds compelling, and it does work in that using these techniques results in a slight statistical advantage in determining who is lying and who isn’t. However, a small statistical advantage is all but worthless in practical application. There are too many false positives and false negatives to be useful. For any individual suspect, at the end of the test you still don’t know if they are lying or not.

Part of the problem is that people are complex and variable. Not everyone responds the same way to stress, or to the situations provoked in the testing. But the problem is worsened by the existence of effective mental countermeasures. There are two basic countermeasures that have been shown to be effective – lowering further the statistical effect of the polygraph. The first is to assign mental significance to control items or questions, thereby reacting similarly to the control and the relevant items. The second is to create mental distance to all the items, including the relevant ones. Focus on something else – the sound of the words, their precise dictionary meaning, or imagine a famous character saying them. If the statements are in writing, you can focus on the color of the ink, the font, or other superficial aspects.

These countermeasure work. They successfully blur any difference between control and relevant items.

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Apr 22 2019

Partially Reviving Dead Pig Brains

I turns out they were only “mostly dead.” Well, it depends on your definition of death.

This is an interesting study that has been widely reported, with a surprisingly small amount of hype. The New York Times writes:

‘Partly Alive’: Scientists Revive Cells in Brains From Dead Pigs
In a study that upends assumptions about brain death, researchers brought some cells back to life — or something like it.

All the reporting I have seen so far has appropriate caveats, but they are really trying hard to maximize the sensational aspects of this study. I actually wrote about this study one year ago when the data was first presented. Now it has been published, so there is another round of reporting (which interestingly ignores the prior reporting).

The quick version is that Yale neuroscientists collected decapitated pig brains four hours after death and then tried to keep the brain cells alive in order to see what would happen. It’s actually a great real-life Frankenstein type experiment, a fact not missed by some outlets. Here is what they did: Continue Reading »

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Apr 08 2019

More Research into Bullshit

Published by under Neuroscience

Often times when I state that I do not accept a claim at face value, I am challenged with the question – “Well, do you think they are lying?” The question results from a false dichotomy – that someone is either telling the truth or consciously lying. It misses a phenomenon that is perhaps vastly more large than conscious lying – bullshit.

Lying is when you say something that you know to be false. Bullshitting is when you say something that you don’t know is true or not. There is a spectrum here also, where people may be exaggerating or stretching what they know to be true, mixing in speculation and opinion with facts, distorting what is known with a conscious or unconscious agenda (motivated reasoning), or they are simply gullible themselves. How carefully do you vet a specific piece of information before you accept it and repeat it as true, and how transparent are you about your sources and your confidence in the information?

Most people, I would argue, are not careful enough. Being skeptical is essentially about being really careful and transparent about the information you accept.

Psychological researchers are trying to understand the phenomenon of bullshit, and actually use that term in the literature. A recent study extends this a bit, and is in line with previous research. Pennycook and Rand looked at 1,606 participants through online surveys. They evaluated how receptive they are to statements which are referred to as “pseudoprofound bullshit” and also their ability to discriminate real news from fake new.

Pseudoprofound bullshit are statements that are designed to superficially sound deep, but are actually utterly meaningless (think of pretty much anything Deepak Chopra says). For example, “Hidden meaning transforms unparalleled abstract beauty.”

There is even a website that generates random “Chopraesque” statements. For example, it just generated for me, “Innocence gives rise to subjective chaos.” This literally just uses an algorithm to string together random words but structured in such a way as to produce such statements.

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Apr 05 2019

The Color of Vowels

Published by under Neuroscience

What is the color, if you had to choose, of the “oo” sound in “boot”? What about the “ay” sound in “say”?

Researchers asked 1,000 participants this question, 200 of which have synesthesia – a condition in which different sensory and cognitive modalities blend into each other. Interestingly, 70% of non-synesthetes still had a structured answer to these questions. They had a mental map of what vowel sounds had which colors.

Synesthesia is a fascinating phenomenon, that is also a good reminder that our brains are just squishy machines, and they have quirky flaws like all machines. Brain function is mostly a result of networks of neurons firing together. There are various biological mechanisms that control the firing of neurons, so that they participate in networks but these electrical signals do not spread randomly through the brain (that’s basically what a seizure is).

These networks are horrifically complex, and interact with each other is complex ways to create neurological function. There are all sorts of variations of this brain wiring that can produce all the variation we see in people, including some that we would consider disorders or pathological.

Synesthesia is more of a condition than a disorder because it does not necessarily cause any demonstrable harm, and may even be an advantage in certain ways. Synesthetes have their brain networks crosses in unusual ways, so that they smell sound, see odors, or hear colors. They may also assign sensations to abstract concepts. Numbers may have a color, texture, or contour, for example. This is not imagination – they really perceive these things.

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Mar 12 2019

Robots Learning to Walk

Researchers at the USC Viterbi School of Engineering have developed a robotic limb with artificially intelligent control that learns how to walk by trying to walk. This may seem like a small thing, but it represents a fascinating trend in AI and robotics – shifting more and more to a bottom up rather than top down approach to programming.

This recent advance is very incremental, but worth pointing out. The researchers tried to designs a limb based on biological principles. Rather than programming the limb with the processes necessary to walk, including dealing with difficult terrain and recovering from a trip, they developed an algorithm that will learn how to walk and adapt by trying to do it. This type of learning algorithm from scratch is nothing new, but the researchers claim this is the first time it was applied to this particular task.

The results were impressive – the robot was able to learn how to walk within minutes. Because the learning is mostly trial and error, different iterations of this algorithm will hit upon different solutions, so different robots might have distinctive gaits.

The first thing I thought of when I read this news item is – what about Boston Dynamic’s Big Dog? This is a four-legged robot about the size of a large dog developed as a pack mule for the military, and capable of handling rough terrain. Watch the video – it’s impressive. I tried to find out how much of the Big Dog walking algorithm is learned vs programmed, but what I found is that “it’s proprietary.” But the consensus of opinion seems to be that it is partly both, a lot of developed walking algorithms but maybe incorporating some learning AI. If true the USC robotic limb would be the first fully self-learning walking robot algorithm, as they claim.

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Feb 11 2019

Caring About Robots

Would you sacrifice a human to save a robot? Psychologists have set out to answer that question using the classic trolley problem.

Most people by now have probably heard about the trolley dilemma, as it has seeped into popular culture. This is a paradigm of psychology research in which subjects are presented with a dilemma – a trolley is racing down the tracks and the breaks have failed. It is heading toward 5 people who are unaware they are about to be killed. You happen to be right next to the lever that can switch the trolley to a different track, where there is only one person at risk. Would you switch the tracks to save the 5 people, but condemning the 1 person to death? Most people say yes. What if in the same situation you were on the trolley at the front of the car, and in front of you was a particularly large person – large enough that if you pushed them off the front of the trolley their bulk would stop the car and save the 5 people, but surely kill the person you pushed over (I know, this is contrived, but just go with it). Would you do it? Far fewer people indicate that they would.

The basic setup is meant to test the difference between being a passive vs active cause of harm to others in the context of human moral reasoning. We tend not to be strictly utilitarian in our moral reasoning, thinking only of outcomes (1 death vs 5), but are emotionally concerned with whether we are the direct active cause of harm to others vs allowing harm to come through inaction or as a side consequence of our actions. The more directly involved we are, the more it bothers us, not just the ultimate outcome.

The trolley problem has become so famous because you can use it as a basic framework and then change all sorts of variables to see how it affects typical human moral reasoning. You can play with the numbers, to see if there is a threshold (how many lives must be saved in order to make a sacrifice worth it?), or you can vary the age of those saved vs those sacrificed, or perhaps the person you might sacrifice is a coworker. Does that make their life more valuable? What if they are kind of a jerk?

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Jan 29 2019

The Law of Unintended Consequences

Published by under Neuroscience

Psychologists have come to recognize that, because of the complexity of human emotion and behavior, we are often motivated to engage in activity which produces the exact opposite effect that we intend. If you are fearful of losing someone, you may become clingy and possessive, driving them away.

The same is true on a societal level – interventions designed to have one effect may have the opposite effect if we are not careful. A classic example is the “scared straight” approach to public service announcements – it doesn’t work. In fact, it may have the opposite of the intended effect. Warning kids about the dangers of alcohol, for example, may just romanticize alcohol use and suggest that it is more popular or common than it is, creating social pressure to use. This is the main idea behind the social norming approach – tell kids, instead, statistics about how few of their peers are getting drunk regularly, reducing the social pressure to use.

This overall pattern is fairly consistent in the literature (although, of course, researching such questions is complex and the details matter to the outcome). Another recent example is a study which finds that fat shaming obese people does not motivate them to lose weight, which is sometimes the motivation (or at least the justification) of the person doing the fat shaming. Rather, fat shaming leads to more weight gain.

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Jan 24 2019

Yawning in Virtual Reality

Published by under Neuroscience

Psychologists are increasingly using virtual reality (VR) in their psychological experiments. It’s very convenient – they can create whatever environment they want with total control over all visual and auditory variables. It’s also safe, so they can study how people respond in traffic without the risk of subjects getting run over.

The meta-question for this research, however, is whether people will respond the same in VR as they do in physical reality? That is a research question unto itself, with implications for all other VR-based research.

Based on my personal experience in VR I would guess that it depends. Current VR technology is of sufficient resolution and fidelity that it successfully tricks the brain – your brain believes that you are in the environment you see. I say “your brain” because you consciously know it is VR and not meat-space, but your brain incorporates the visual and auditory sensory streams into its construction of reality as if they were real. So, consciously you may know the difference, but subconsciously you don’t.

Perhaps the best demonstration of this is the Planck Experience – a fun little VR demonstration in which you walk out onto a planck 40 floors high on a virtual skyscraper. You know you are safe in a room, but your subconscious brain buys the visual construction and your emotions react as if you are about to die.

A recent experiment adds a bit more data to this question. Researchers used VR to test yawning. There is a phenomenon of contagious yawning – mammals will yawn when they see other mammals yawn, about 30-60% of the time. So the researcher put subjects in VR where they were exposed to virtual yawning. Sure enough – the yawns were contagious 38% of the time, in the range of previous research.

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Jan 22 2019

New Technique to Map Brains

Published by under Neuroscience

One of the “holy grails” of neuroscience is the ability to scan a brain and create a complete detailed map, including all networks and connections. Scientists use several techniques, all with their own drawbacks, and the process is very slow – it can take a year to completely scan a single fly brain. A collaboration of scientists, however, report in Science that they have developed a new technique that can accomplish a detailed scan of an entire fly brain (or a section of mouse cortex) in 2-3 days.

The team has been described as an “Avengers” type collaboration, and it is impressive. Specialists provided the prepared fly brains. Two different types of microscopy were combined (that’s really the new bit), along with a third imaging technique. Finally, computer specialists had to figure out how to combine all the data like puzzle pieces into an image. The result was a complete map of a fly brain in three days, which is an impressive leap forward.

The core innovation of the new technique is to use a combination of expansion microscopy and lattice light-sheet microscopy. Expansion microscopy is pretty much what it sounds like – the brain sample is expanded, retaining the relative positions of neurons and connections, but creating more space to facilitate imaging. Expansion is done chemically, similar to injecting an expanding gel into a specimen. The researchers expanded their samples four-times to provide optimal results. The potential problem with this technique is that it may introduce artifacts giving spurious results, so anyone using it has to be careful and validate their techniques (by reproducing known outcomes, for example).

This expansion technique was combined with the lattice light-sheet microscopy. This is a complicated setup that illuminates the specimen with high energy thin sheet of light, only that part of the specimen that is in focus to the microscope, keeping all the out-of-focus parts dark. Finally, this is all combined with fluorescence microscopy, which tags specific biological structures (such as certain amino acids) with fluorescent molecules. This way only certain cell types or certain connections or structures can be imaged and mapped. Specifically they used confocal microscopy, which provides better resolution and contrast.

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Jan 18 2019

GM Foods and Changing Minds

The question at the core of science communication and the skeptical movement is – how do we change opinions about science-related topics? That is the ultimate goal, not just to give information but to inform people, to change the way they think about things, to build information into a useful narrative that helps people understand the world and make optimal (or at least informed) decisions.

I have been using the GMO (genetically modified food) issue as an example, primarily because the research I am discussing is using it as a topic of study. But also – GMO opposition is the topic about which there is the greatest disparity between public and scientific opinion. A new study also looks at attitudes toward GMOs, specifically, with the question of – is a convert from GMO opponent to supporter more persuasive than straightforward GMO support?

The study uses clips from a talk by Mark Lynas, an environmentalist who converted from GMO opponent to supporter. They found:

The respondents each were shown one of three video clips: 1) Lynas explaining the benefits of GM crops; 2) Lynas discussing his prior beliefs and changing his mind about GM crops; and 3) Lynas explaining why his beliefs changed, including the realization that the anti-GM movement he helped to lead was a form of anti-science environmentalism.

The researchers found that both forms of the conversion message (2 and 3) were more influential than the simple advocacy message. There was no difference in impact between the basic conversion message and the more elaborate one.

This makes sense – prior research shows that it is more effective to give someone a replacement explanatory narrative than just to tell them that they are wrong. However, it is very difficult to say how generalizable this effect is.

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