Archive for the 'Neuroscience' Category

Jan 14 2019

Our Memories Work Backwards

Published by under Neuroscience

One more piece to the memory puzzle seems to be falling into place. The question is – what steps do our brains go through when recalling a memory? Researchers have been focusing on visual memory, because it is easiest to model and image, and they have found that memories are recalled in a reverse of the process by which they are formed.

A recent study in Nature Communications replicates the overall findings of a previous study published in PNAS. Both studies looked at the visual system and found essentially the same thing.

When we perceive an object, first our brain receives an image from the retina. By the time this image gets to the visual cortex some basic image processing has already occurred at the subcortical level. Then the cortex puts the image together, sharpens up contrast and lines, interprets size and distance, shadows and movement, etc. The brain then tries to find a match in its catalogue of known things. Once a match is found, actually, that information is then communicated back down to the more basic visual layers and the image is adjusted to enhance the match – lines are filled in, extraneous details are suppressed, assumptions of size and distance are adjusted.

Then the now identified object is sent to even higher brain areas (higher in this network) to afford meaning to the object. If your brain thinks the object has agency, this connects to the emotional centers in order to remember what you feel about the object. Connections are also made to memories about the object. Let’s call these thematic memories. So our brains build the image up from basic details, to complex shapes, then to known objects, and finally to feelings, connections, meaning and memories.

But what about when you recall the object that you previously saw? Both of these studies, using visual memories, found that the brain works backwards. First the thematic areas of the brain light up, then progressively more basic areas of visual processing. Media reporting on these studies emphasize that this is backward from how visual memories are made in the first place. However, this is only sort-of true. Remember – even when perceiving things, information goes simultaneously from the details to the themes, but then back down from the themes to the details. Perception and memory formation is bidirectional.

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Jan 10 2019

Children and Screen Time

Most parents worry about how much time their children are spending in front of computer screens, smartphones, and other electronic devices. This is a reasonable worry – this is a fairly dramatic cultural change, and the experience is different than what most of today’s parents experienced when they were children.

Pediatricians have also been warning about excessive screen time, which has been linked to obesity. But current research and recommendations are getting more nuanced, and pediatric organizations have recently walked back or altered their recommendations.
A recent review published in the BMJ found:

We found moderately strong evidence for associations between screentime and greater obesity/adiposity and higher depressive symptoms; moderate evidence for an association between screentime and higher energy intake, less healthy diet quality and poorer quality of life. There was weak evidence for associations of screentime with behaviour problems, anxiety, hyperactivity and inattention, poorer self-esteem, poorer well-being and poorer psychosocial health, metabolic syndrome, poorer cardiorespiratory fitness, poorer cognitive development and lower educational attainments and poor sleep outcomes. There was no or insufficient evidence for an association of screentime with eating disorders or suicidal ideation, individual cardiovascular risk factors, asthma prevalence or pain. Evidence for threshold effects was weak. We found weak evidence that small amounts of daily screen use is not harmful and may have some benefits.

The evidence is weak, and correlational only. This means we cannot conclude that screen time causes obesity, anxiety, or other issues. It may be, for example, that children who are sedentary for other reasons are both overweight and engage in sedentary activities, many of which involve screen time.
Based on this review, The Royal College of Paediatrics and Child Health said that there is insufficient evidence to conclude that screen time in itself is “toxic.”

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Jan 08 2019

Misunderstanding Dunning-Kruger

Published by under Neuroscience

There is, apparently, an increase recently in interest in the Dunning-Kruger effect. The Washington Post writes about this recently, making the obvious political observation (having to do with the current occupant of the White House). It’s great that there is public interest in an important psychological phenomenon, one central to critical thinking. I have discussed DK before, and even dedicated an entire chapter to discussing it in my book.

Unfortunately the Post misinterpret the DK effect in the common way that it is most often misinterpreted. They write:

Put simply, incompetent people think they know more than they really do, and they tend to be more boastful about it.

and

Time after time, no matter the subject, the people who did poorly on the tests ranked their competence much higher. On average, test takers who scored as low as the 10th percentile ranked themselves near the 70th percentile. Those least likely to know what they were talking about believed they knew as much as the experts.

The first sentence makes it seem like the DK effect applies only to people who are “incompetent.” This is wrong on two levels. The first is that the DK effect does not apply only to “incompetent people” but to everyone, with respect to any area of knowledge. To be fair the author also writes, “it is present in everybody to some extent,” but this does not really capture the reality, and is undone by the sentences above. Second, the effect applies not just in the range of incompetence, but even for average or moderately above average competence.

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Dec 21 2018

Radical Political Views Correlates with Poor Metacognition

The usual caveats apply – this is one study in a limited context showing only correlation and using a psychological construct. I also have to be careful because the study confirms what I already believe. Having said all that, it is interesting and is probably telling us something about people with extreme political views, especially when other research is considered.

The study involves individuals with radical political beliefs, as measured by a standard questionnaire. It has already been established that those with more extreme beliefs espouse greater confidence in their knowledge and beliefs. However, it is not clear how much this is due to an overconfidence bias vs a failure of metacognition. In other words – do people who are overconfident about their political beliefs like to portray themselves to others as being confident, or do they simply lack insight into the correctness of their own beliefs (a metacognitive failure). The current study tests the latter factor.

The researchers, lead by Steven Flemming at University College London, looked at, “two independent general population samples (n = 381 and n = 417).” He gave them a challenge in which they had to estimate the number of dots on two images, and decide which one had more. They also had to say how confident they were in their judgement. Further, if they got the answer wrong, they were given further information in the form of another image with dots which should have helped them improve their estimate. They were then asked to restate their confidence.

The study found that those with more radical political views indicated higher confidence in their choices, even when they were wrong, and less of a tendency to update their confidence with new information. In other words – you might say they are opinionated and stubborn.  This comes as absolutely no surprise if you have ever interacted with someone with extreme political views.

What this study cannot tell us about is the arrow of cause and effect. One possibility is that those who lack the metacognitive ability to properly assess and correct their own confidence levels will tend to fall into more extreme views. Their confidence will allow them to more easily brush off dissenting opinions and information, more nuanced and moderate narratives, and the consensus of opinion.

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Dec 13 2018

Delay School Start Times

Published by under Neuroscience

Living in a complex society means that some decisions are made for us. In a representative democracy, this means our elected officials, at every level, can have incredible power over our lives. The social contract, however, is that these elected officials should know what they are doing, act in the public interest, listen to their constituents, and engage in due diligence based on valid evidence-based processes. Well, that’s the ideal, and it’s pretty clear that we generally fall far short.

One limitation is that people are flawed and have complex motivations and often fall prey to ideology. However, there is also a collective problem of political will, with often perverse incentives baked into the system itself.

These inherent flaws in the system become increasingly frustrating as there are obviously better ways to do things, and yet we can’t seem to get out of our own way. On the bright side it is possible to slowly build the political will in response to a growing body of evidence. Scientific evidence on the risks of second-hand smoke, for example, supported the political will to ban smoking in many public locations, which has led to an improvement in health.

But there are other areas where the science is increasingly clear, the arguments seem one-sided, and yet we seem to be stuck in paralysis. Changing from Daylight Savings time to Standard time is hazardous. It is linked to worse sleep, more accidents, and even more heart attacks. There is also no good reason for the change. It’s just dumb. It seems that we are long past the time of having enough evidence, arguments, and political will to just ditch the change – so what’s the holdup?

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Dec 11 2018

Study – Mental Activity Does Not Prevent Decline

Published by under Neuroscience

There has been a very interesting debate going on in neuroscience over the impact of so-called “brain training” activities and cognitive ability and decline. No one study, of course, is ever going to be the final word on this debate, but a new study does add one more piece to the puzzle. Unfortunately it shows that increased mental engagement (doing puzzles, engaging in problem solving, etc.) does not alter the course of mental decline in later years.

But let’s back up and frame the question a bit more. The overarching question is – what is the effect on the brain and on cognitive ability from engaging in various kinds of mental activity? A cottage industry has risen out of one extreme end of opinion on this question, the notion that certain kinds of mental activity could have wide ranging benefits. This is the “brain training” claim – doing specially designed puzzles will make you smarter, and maybe even prevent dementia.

Although Lumosity often gets cited for making these claims, I think it started much earlier, in the 1990’s with the Baby Mozart movement. In 1993 a short paper was published in Nature, involving a small number of college students who were either exposed to classical music or just relaxation. They were then tested with a paper folding task, and those who listened to the music did a litter better. This was a small preliminary study in college students showing a very narrow effect. Yet somehow this tiny and insignificant paper was used to create the myth of the so-called “Mozart effect” – that children who are exposed to classical music will become generally smarter.

Later studies showed no such effect, but the genie was out of the bottle. A cottage industry of “Baby Mozart” and “Baby Einstein” (because, why not?) products still thrive to this day. This spawned a more general claim that mental activity can “train your brain” to make you generally smarter.

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Nov 09 2018

Navigation May Be Fundamental to Thinking

Published by under Neuroscience

Have you ever been in a semi-familiar location but couldn’t quite place where you were, then suddenly the landmarks line up and you know where you are? This might happen when entering a familiar location from an unusual direction, for example. Also (a seemingly unrelated question), when you visualize abstract ideas, do you arrange them physically. For example, do you visualize time (like days, weeks, months, years), and if so is there a particular physical relationship by which you mentally organize the progress of time?

Scientists from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) and the Kavli Institute for Systems Neuroscience in Trondheim, Norway have published a paper in which they propose these two mental phenomena are directly related. One of the scientists, Edvard I. Moser, won the 2014 Nobel Prize for some of this work.

For background, researchers discovered that there are a type of neuron called place cells in the hippocampus (specifically area CA1) that store the memory for specific locations. When you are in a familiar location, a unique pattern of place cells will light up. Further, there is a second type of cell called grid neurons, which are arranged in a hexagonal pattern in the nearby entorhinal cortex. These grid cells light up in sequence as you move through your physical space – the physical arrangement of the grid neurons map to the physical arrangement of your environment.

This is an elegant system – your brain basically has a movable grid map, the grid keeps track of your local navigation, while the place cells keep track of where the map is.

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Nov 01 2018

Learning from Video

Is putting your toddler in front of an educational video harmful or helpful? This is an important question for many parents, especially in homes where both parents work and taking care of young children can be hectic. Putting a child in front of a video is the closest things parents have to an off switch for their kids, so it can be very tempting to rely upon the distraction of an iPad or TV to keep their attention while you make dinner or attend to some other task.

There is also a cottage industry of videos marketed to parents with very young children. Some are clearly nothing more than an entertaining distraction, like videos of other children playing with toys (which are incredibly popular). But parents can also be sold on the idea that their children are learning while being distracted, thereby alleviating any guilt from relying on the video-nanny.

There has therefore been increasing research into the effectiveness of video learning for very young children (and older children and adults, but we’ll focus on young children for now).  Here is a recent study of this topic which includes a great overview of prior research.

Previous research has mostly shown that young children do not respond to video the same way they respond to a live person. Exposing toddlers to their native language or a foreign language through a video or just audio seems to have no benefit, compared to the identical content presented through a live person. The probable reason for this is that we are programmed from birth to be extremely social, and young children typically will pay great attention to other people – more than anything else. A video of a person, unfortunately, just doesn’t cut it.

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Oct 01 2018

Cheating vs Loyalty

Published by under Neuroscience

How people make ethical decisions is a very interesting line of psychological research. Perhaps the most well-known study is the famous trolley experiment. It is a theoretical question, if you are at the controls of a switch that can change tracks, and a trolley is out of control and heading toward five people that it will surely kill, would you switch the trolley onto another track that only has one person on it? Most people say that they will – they will sacrifice that one person in order to save five.

However, if you are standing next to the track and a very large person is in front of you, would you push them onto the tracks in order to stop the train and save five people (just go with the premise for the sake of the ethical conundrum). Most people will say no. In scenario 1 they will sacrifice one person to save five, in scenario 2 they will not. Why?

Conventional wisdom is that people are more willing to passively allow someone to die rather than actively kill them. The outcome matters less than the mechanism – emotionally, at least.

The deeper issue here, beyond this one ethical calculation, is how we make ethical calculations generally. This mainly comes down to conflict resolution – when competing motivations are moving us toward different behaviors, how do we resolve the conflict? We make such ethical decisions on two levels, intuitive and analytical (the two basic modes of thought that have been elucidated in other contexts as well).

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Sep 06 2018

Superstition and the Illusion of Control

Published by under Neuroscience

Humans tend to be superstitious creatures, meaning that we sometimes believe in magical causation – if I wear my lucky sweater my favorite team will win. Psychologists have been examining this strange phenomenon for decades, with some interesting results.

A recent study ads one more piece of information to the emerging picture of what drives superstitious beliefs and behaviors, but let’s first give some background.

Superstitious beliefs are primarily about the illusion of control – the feeling that we have some direct or indirect control over the outcome of processes over which we objectively have zero control. Gambling is a common everyday example – gamblers tend to develop all sorts of behaviors they believe will give them a better chance of winning at games which are random. Psychologists divide the notion of control into primary and secondary. Primary control is direct control – if I throw the dice with my left hand I will get a better result. Secondary control is an attempt to harness or align with an outside force, such as luck.

It is always difficult to tease apart the complex causes of human decision-making and behavior, and studies necessarily rely on artificial situations or markers of the behavior in question. But a few fairly clear signals have emerged from the research.

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