Archive for the 'Neuroscience' Category

May 28 2020

Confidence Drives Confirmation Bias

Published by under Neuroscience

Human thought processes are powerful but flawed, like a GPS system that uses broken algorithms to lead you to the wrong destination. Psychologists study these cognitive biases and heuristic patterns of thought to better understand these flaws and propose possible fixes to mitigate them. To a large degree, scientific skepticism is about exactly that – identifying and compensating for the flaws in human cognition.

Perhaps the mother of all cognitive biases is confirmation bias, the tendency to notice, accept, and remember information that confirms what we already believe (or perhaps want to believe), and to ignore, reject, or forget information that contradicts what we believe. Confirmation bias is an invisible force, constantly working in the background as we go about our day, gathering information and refining our models of reality. But unfortunately it does not lead us to accuracy or objective information. It drives us down the road of our own preexisting narratives.

One of the things that makes confirmation bias so powerful is that it gives us the illusion of knowledge, which falsely increases our confidence in our narratives. We think there is a ton of evidence to support our beliefs, and anyone who denies them is blind, ignorant, or foolish. But that evidence was selectively culled from a much larger set of evidence that may tell a very different story from the one we see. It’s like reading a book but making up your own story by only reading selective words, and stringing them together in a different narrative.

A new study adds more information to our understanding of confirmation bias. It not only confirms our selective processing of confirming information, it shows that confidence drives this process. So not only does confirmation bias lead to false confidence, that confidence then drives more confirmation bias in a self-reinforcing cycle.

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May 25 2020

Can We See Personality?

Published by under Neuroscience

Is someone’s basic personality type written on their face? This is an interesting question, that research has not definitively answered. A new study uses AI to add one more piece of information, suggesting that the answer is – maybe, sort of.

Let’s start with a technical definition of personality:

“Personality refers to individual differences in characteristic patterns of thinking, feeling and behaving.”

It is uncontroversial that different people have different personality traits, although there are different schemes for how to divide up all the different recognizable personality traits people might display. One of the more accepted schemes is OCEAN (the big five) – Openness, Conscientiousness, Extroversion, Agreeableness, and Neuroticism. This does not capture every aspect of one’s personality, nor the rich background of experience and culture that helps mold our behavior, but it does seem to capture something fundamental about how humans vary.

Far more controversial is whether or not there are different personality types, meaning a suite of personality traits that tend to go together. There are many tests based on the assumption that people can be sorted into a small number of different personality types, but none of them have established validity. The best evidence we have so far, in my opinion, does not support the notion of personality types in any meaningful way.

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May 21 2020

Localizing Executive Function

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Where in the brain is a specific ability located? This is a more complex question than it may at first seem, mainly because we first have to define each specific ability. Some are obvious, like the ability to voluntarily move your right hand. The motor strip in the cortex physically maps to the body, and it is relatively easy to correlate a specific part of the brain to weakness of any specific body part. But even something as simple as motor control has many layers – other parts of the brain that modify control, allowing for smooth coordinated movement, for example.

Arguably the most difficult functions to localize in the brain are the more abstract ones, like executive function. This is extremely challenging partly because we don’t really know what those functions are at their most fundamental level. We can learn what behaviors they allow, but how? What is actually happening in the brain when you make a decision, for example?

Some of these more abstract functions are also difficult to study because they may be bilateral, meaning that the same structure on both sides of the brain contribute to the function. Therefore a lesion taking out one side won’t necessarily cause any deficits. Motor control, by contrast, is unilateral, so one single lesion causes an obvious deficit. This is important because studying lesions is one major way neuroscientists localize brain function – wait for it to break and than see what doesn’t work. Historically such lesion studies have been the most important method for mapping the brain.

Today we have other methods, such as imaging the brain functioning (fMRI), mapping electrical activity with EEG, and even temporarily influencing brain function with electrical or magnetic stimulation. This data (the first two methods, anyway), however, is mostly correlational. It can still be powerful, but a lesion is helpful in confirming causation.

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May 15 2020

Stimulating the Visual Cortex

Published by under Neuroscience

For adults who had vision but then lose it due to eye disease or damage to the optic nerve, their visual cortex is still intact. It is deprived if input, but is theoretically capable of functioning normally to create images. The ultimate technological expression of this potential would be something like the visor of Geordi La Forge – a device that can see (even in frequencies and particles humans cannot normally see) and transfer that information to the visual cortex. Obviously we are a long way away from any such technology, but we have taken the first baby steps in that direction, including a recent study which makes one tiny advance (but more on that shortly).

Early research into this approach involved animals and simply tried to determine if the monkeys could “see” the stimulation. Often simple behaviors, like moving their eyes, were used to see if the stimulation was having any effect. Some of the research also comes from trying to map the visual cortex, not necessary allow the blind to see. This research has been encouraging, because it shows that the primary visual cortex is arranged in a way to reflect the images it sees (so-called retinal mapping). The neurons, in short, are like a bitmap of an image. So if you stimulated a circle of neurons in the primary visual cortex, subjects would see a circle.

Of course there is more to vision than the primary visual cortex. A lot of processing occurs in the nerves  and pathways carrying information to the cortex. After the basic image is formed it is then sent to higher visual cortical areas for further processing, so a two-dimensional image is given shape, shading, movement, distance, three-dimensionality, and ultimately meaning. But hopefully we wouldn’t need to worry about all that higher levels of processing because once the image is presented to the primary visual cortex, the rest should take care of itself.

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May 05 2020

The Psychology of Buying More

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When I was in college I had just finished a course on social psychology (certainly one of the most memorable courses I took in college), and while back home I was visiting with my then girlfriend. When I arrived they were in the middle of dealing with a door-to-door textbook salesperson. That’s right – the product was a mathematics textbook that combined the K-12 curriculum into one giant tome. My girlfriend’s parents asked my advice, so I sat down to listen to the spiel.

The salesman was sitting in their living room, sitting on one side while the family members were all opposite. He had a velcro cast on one of his legs (the kind that can be removed and put back on) and was sporting crutches. His tactic was largely highlighting some feature of the book, then asking someone specifically if they thought that feature would be helpful. “Do you think it would be helpful to all this information in one location?” The answer, of course, was always yes. He mentioned that a neighbor down the street had just purchased the book for their high school student.

It was a fascinating experience for me, because I had just learned about all of the techniques the salesman was using. He was garnering sympathy with the cast. Using peer pressure by mentioning their neighbors. Getting them to agree that the product was useful, so they would feel inconsistent if they then decided not to buy. He positioned the family all on one side so they could not make eye contact with each other during his presentation.

After the pitch, while the book salesman was still waiting in the living room, I told the parents not to buy the book. I explained all the manipulative techniques he was using. Further, they simply did not need the book, and it was expensive. They understood, but bought the book anyway. They felt he had invested so much time in the sales visit they could not say no. His emotional manipulations worked – even when they knew they were being manipulated. It would have been simply too socially awkward to send him away with no sale.

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May 01 2020

Nanotechnology to Treat Alzheimer’s Disease

This is a very cool study, with the massive caveat that it is extremely preliminary – but scientists have concluded an in vitro study of nanodevices that can reduce one of the pathological changes thought to be a significant cause of Alzheimer’s disease. This has to be put into context, but let me first describe what they did.

Alzheimer’s disease (AD) is a neurodegenerative disorder that affects the brain diffusely. Little by little brain cells die, the brain atrophies, and cognitive ability slowly declines causing dementia. The disease affects about 10% of people over 65, producing a huge burden on individuals, families, and society. As our population ages, it is becoming even more prevalent. There is extensive research on how Alzheimer’s disease progresses, looking for clues that might lead to an effective treatment. However, it has proven a tough nut to crack. We have many clues, but nothing that has lead to a treatment that can prevent, stall, or reverse the neurodegeneration. It is, in short, a complex disease.

One piece of this complex puzzle is the β-amyloid peptide (Aβ), which is a breakdown product of an amyloid protein precursor. The simple version is that this peptide is normally cleared from brain cells as a waste product, but in some individuals it is not sufficiently cleared and there is enough hanging around to form conglomerations or clumps of the protein. These clumps form plaques, which are a major pathological sign of AD. However, the picture is more complex than that. The amount of plaques in the brain don’t necessarily correlate with the severity of the dementia in AD, so it is clearly not the whole picture. More recent studies have found:

Substantial evidence now indicates that the solubility of Aβ, and the quantity of Aβ in different pools, may be more closely related to disease state. The composition of these pools of Aβ reflects different populations of amyloid deposits, and has definite correlates with the clinical status of the patient.

There are also pathological processes in AD that are not related to amyloid plaques, so again we are only dealing with part of the picture here. Still, researchers have been looking for ways to prevent plaque formation as a possible way to slow, stop, or even reverse AD. So far nothing has led to an approved treatment. (Current treatments for AD are only symptomatic.)

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Apr 27 2020

Psychological Pitfalls and COVID-19

SARS-Cov2 is a challenging little bugger, but in my assessment no match for human science and ingenuity. There are already 1,650 listed scientific articles on COVID-19 and 450 ongoing clinical trials. In short, we are scienceing the shit out of this pandemic and we will get through it. But as I have argued previously, perhaps a bigger threat than the virus itself is human psychology. Crises bring out the best and worst in people, and we are seeing both in spades. Also, a crisis exposes the weaknesses in institutions, and they are being highlighted as well.

That’s why, in medicine, we have something called M and M – morbidity and mortality rounds. The goal of these rounds is to review all negative clinical outcomes in whatever setting is being covered and try to figure out what went wrong. But, importantly, such conferences are not about assigning blame, recrimination, or discipline. It is about improving the system. Was a particular negative outcome unavoidable? Was it precipitated by a personal failure, or rather a systemic failure. And if not a failure per se, is there some systematic change we can put in place to minimize these negative outcomes in the future? Should this be handled by education, by some additional checklist or process, or by reconfiguring the workforce?

For some crises, like the pandemic (or a war, for example), we can’t wait until it’s all over to look back and analyze the systemic shortcomings (although we should do this also, to prepare for the next one). We need ongoing analysis and adjustment. That is what a group of psychologists have done, with respect to common psychological pitfalls and how they might affect our individual response to the pandemic. I like this review because it is square in the tradition of skeptical thinking – it identifies psychological pitfalls so that we can better understand ourselves, and proposes specific adjustments we can do to mitigate them. You can read the full article, but I want to highlight a few of particular interset.

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Apr 13 2020

Demand Characteristics in Psychological Research

Published by under Neuroscience

I have written quite a bit about the body part ownership illusion (sometimes called the “rubber hand illusion” because of the original study design). The idea is that the brain constructs all our sensations, perceptions, and experiences, including the sense that we own, occupy, and control our various body parts and our whole body. All it takes, apparently, is synchronization between seeing the “rubber hand” being touched and feeling your own hand being touched. Visual-tactile synchrony triggers the sensation of ownership. There is a robust replicated body of research supporting this conclusion. But particularly when people are the subject of research, no conclusion is beyond reconsideration.

That is the core strength of science – it constantly questions and reexamines its own assumptions and conclusions. Psychological research especially needs to do so, because human behavior is horrifically complicated and we cannot directly see (well, not yet) what is happening in someone’s mind, so we have to infer what is happening from things like behavior. That inference is usually based on some construct – some idea about how people operate and how this will translate into their behavior in a psychological experiment.

For example, there is the now famous marshmallow test. In this robust series of experiments, children were offered a marshmallow (or some treat) and told they could eat it now, but if they wait a few minutes the researcher would be back with a second marshmallow and they could have two. The construct for these experiments is that children with more ability to defer gratification through executive function will be able to hold out for the second marshmallow. So in the end this is meant as an experimental measure of executive function. This conclusion was accepted for decades – until it was questioned. There is another possible interpretation of the results – at least some of the children who don’t hold out and go right for the initial treat may not trust that the researcher will be back with more. They will take the bird-in-the-hand. This is a rational response – especially if you have lived your life with adults who are less trustworthy and where basic resources may be limited. And in fact children from lower socioeconomic backgrounds, with less trust and stability, generally do worse on the marshmallow test.

We may now be facing a similar reinterpretation of the body owernership illusion experiments, although at this point I don’t think it is going to turn out that way. A new paper, however, does point out a very important consideration that this and similar research must take into consideration – the role of demand characteristics. The idea itself is nothing new. In psychological experiments the study design must take into consideration the fact that subjects subconsciously try to figure out what the experimenter wants and then gives it to them. Any subtle cue that one response is more desired than another can affect the outcome. So the influence of demand characteristics must be carefully controlled for.

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Mar 31 2020

Decoding Speech from Brainwaves

Here is yet another incremental advance in brain-machine interface (BMI) technology – decoding what someone is saying from their brainwaves using a neural network and machine learning. We are still a distance away from using a system like this to allow someone who cannot speak to communicate, but the study nicely illustrates where the technology is. Here is the BBC’s reporting:

Scientists have taken a step forward in their ability to decode what a person is saying just by looking at their brainwaves when they speak.

They trained algorithms to transfer the brain patterns into sentences in real-time and with word error rates as low as 3%.

Previously, these so-called “brain-machine interfaces” have had limited success in decoding neural activity.

Now here are all the caveats from the paper. First, the technology used electrocorticography (ECoG), which is an EEG with brain surface electrodes. So this requires an invasive procedure, and persistent electrodes inside the skull and on top of brain tissue. Also, in order to get the best performance, they used a lot of electrodes – resulting in 256 channels (a channel is a comparison in the electrical activity between two electrodes). They simulated what would happen with fewer electrodes by eliminating many of the channels in the data, down to 64, and found that the error rates were about four times greater. The authors argue this is “still within the usable range” but they consider usable range up to a 20-25% error rate. What this shows is that – yes, more electrodes matter. You need the very fine discrimination of brain activity in order to get good (usable) results.

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Mar 24 2020

Body Ownership Illusion

Published by under Neuroscience

A new study offers a small advance in our understanding of the body ownership illusion, but it is a good opportunity to review this cool and important neurological phenomenon. It also has practical implications. The body ownership illusion is the subjective sense that you occupy or own your body and its parts. There is also a separate phenomenon that gives you the subjective sense that you control your body parts.

What I find extremely interesting about these phenomena is that we initially didn’t know they needed to exist. People don’t generally wonder what creates the sense that they own and control their own bodies. It’s not even a question people think to ask (unless they are somehow involved in neuroscience). At first it may seem obvious – we are our bodies, and we do control our bodies, so why shouldn’t we have that sense? But like everything you experience and feel, this is not a passive or automatic sensation. It is an active construction of your brain. There are dedicated circuits in the brain whose specific function is to create these sensations.

As with most neurological phenomena we first suspected their existence by encountering patients who have suffered brain damage (like from a stroke) and therefore have a lack of some subset of these functions. For example, there is alien-hand syndrome. This is the sense that a body part is acting “on it’s own” without your conscious control. There are also cases that demonstrate the separation of body parts from the sense that we own those body parts. Phantom limbs, for example, occur when a limb is removed but the brain circuitry that creates the sense of ownership of the limb is still there. There can even be supernumerary phantom limbs – an illusion of an extra limb that was never there. This can happen when a stroke paralyzes a limb but spares the circuitry that creates the sense of ownership. There are also cases of the apparent opposite – when a limb is present and functioning, but the person has the uncomfortable sense that it does not belong to them. We also have evidence from certain drug-induced and other states of feeling entirely separated from our bodies.

We have a partial understanding of how our brains create these sensations. They all involve circuits that compare two or more inputs. When they are synchronous we have the subjective sense of ownership or control. For the sense of control the circuits compare our intention to move and our actual movements. When they match, we feel we have control. For ownership the primary circuit involves “visual-motor synchronization” or visual-sensory synchronization. If what we see of ourselves matches what we feel, that synchronization produces the sense of ownership. Obviously, we don’t immediately have an out-of-body experience when we close our eyes. There are other sensory inputs that act redundantly – proprioception, vestibular function, tactile sensation, and muscle feedback. It’s a robust system, which is why the illusion rarely breaks in day-to-day life. You have to disrupt the main parts of the brain producing this sensation with drugs, oxygen deprivation, or something else.

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