Pupil size surprisingly linked to differences in intelligence

What can you tell by looking into someone’s eyes? You can spot a glint of humor, signs of tiredness, or maybe that they don’t like something or someone. 

But outside of assessing an emotional state, a person’s eyes may also provide clues about their intelligence, suggests new research. A study carried out at the Georgia Institute of Technology shows that pupil size is “closely related” to differences in intelligence between individuals. 

The scientists found that larger pupils may be connected to higher intelligence, as demonstrated by tests that gauged reasoning skills, memory, and attention. In fact, the researchers claim that the relationship of intelligence to pupil size is so pronounced, that it came across their previous two studies as well and can be spotted just with your naked eyes, without any additional scientific instruments. You should be able to tell who scored the highest or the lowest on the cognitive tests just by looking at them, say the researchers.

The pupil-IQ link

The connection was first noticed across memory tasks, looking at pupil dilations as signs of mental effort. The studies involved more than 500 people aged 18 to 35 from the Atlanta area. The subjects’ pupil sizes were measured by eye trackers, which use a camera and a computer to capture light reflecting off the pupil and cornea. As the scientists explained in Scientific American, pupil diameters range from two to eight millimeters. To determine average pupil size, they took measurements of the pupils at rest when the participants were staring at a blank screen for a few minutes.

Another part of the experiment involved having the subjects take a series of cognitive tests that evaluated “fluid intelligence” (the ability to reason when confronted with new problems), “working memory capacity” (how well people could remember information over time), and “attention control” (the ability to keep focusing attention even while being distracted). An example of the latter involves a test that attempts to divert a person’s focus on a disappearing letter by showing a flickering asterisk on another part of the screen. If a person pays too much attention to the asterisk, they might miss the letter. 

The conclusions of the research were that having a larger baseline pupil size was related to greater fluid intelligence, having more attention control, and even greater working memory capacity, although to a smaller extent. In an email exchange with Big Think, author Jason Tsukahara pointed out, “It is important to consider that what we find is a correlation — which should not be confused with causation.”

The researchers also found that pupil size seemed to decrease with age. Older people had more constricted pupils but when the scientists standardized for age, the pupil-size-to-intelligence connection still remained.

Why are pupils linked to intelligence?

The connection between pupil size and IQ likely resides within the brain. Pupil size has been previously connected to the locus coeruleus, a part of the brain that’s responsible for synthesizing the hormone and neurotransmitter norepinephrine (noradrenaline), which mobilizes the brain and body for action. Activity in the locus coeruleus affects our perception, attention, memory, and learning processes.

As the authors explain, this region of the brain “also helps maintain a healthy organization of brain activity so that distant brain regions can work together to accomplish challenging tasks and goals.” Because it is so important, loss of function in the locus coeruleus has been linked to conditions like Alzheimer’s disease, Parkinson’s, clinical depression, and attention deficit hyperactivity disorder (ADHD).

The researchers hypothesize that people who have larger pupils while in a restful state, like staring at a blank computer screen, have “greater regulation of activity by the locus coeruleus.” This leads to better cognitive performance. More research is necessary, however, to truly understand why having larger pupils is related to higher intelligence. 

In an email to Big Think, Tsukahara shared, “If I had to speculate, I would say that it is people with greater fluid intelligence that develop larger pupils, but again at this point we only have correlational data.”

Do other scientists believe this?

As the scientists point out in the beginning of their paper, their conclusions are controversial and, so far, other researchers haven’t been able to duplicate their results. The research team addresses this criticism by explaining that other studies had methodological issues and examined only memory capacity but not fluid intelligence, which is what they measured.

Link Original: https://bigthink.com/surprising-science/pupil-size-intelligence


A unique brain signal may be the key to human intelligence

Though progress is being made, our brains remain organs of many mysteries. Among these are the exact workings of neurons, with some 86 billion of them in the human brain. Neurons are interconnected in complicated, labyrinthine networks across which they exchange information in the form of electrical signals. We know that signals exit an individual neuron through a fiber called an axon, and also that signals are received by each neuron through input fibers called dendrites.

Understanding the electrical capabilities of dendrites in particular — which, after all, may be receiving signals from countless other neurons at any given moment — is fundamental to deciphering neurons’ communication. It may surprise you to learn, though, that much of everything we assume about human neurons is based on observations made of rodent dendrites — there’s just not a lot of fresh, still-functional human brain tissue available for thorough examination.

For a new study published January 3 in the journal Science, however, scientists got a rare chance to explore some neurons from the outer layer of human brains, and they discovered startling dendrite behaviors that may be unique to humans, and may even help explain how our billions of neurons process the massive amount of information they exchange.

Electrical signals weaken with distance, and that poses a riddle to those seeking to understand the human brain: Human dendrites are known to be about twice as long as rodent dendrites, which means that a signal traversing a human dendrite could be much weaker arriving at its destination than one traveling a rodent’s much shorter dendrite. Says paper co-author biologist Matthew Larkum of Humboldt University in Berlin speaking to LiveScience, “If there was no change in the electrical properties between rodents and people, then that would mean that, in the humans, the same synaptic inputs would be quite a bit less powerful.” Chalk up another strike against the value of animal-based human research. The only way this would not be true is if the signals being exchanged in our brains are not the same as those in a rodent. This is exactly what the study’s authors found.

The researchers worked with brain tissue sliced for therapeutic reasons from the brains of tumor and epilepsy patients. Neurons were resected from the disproportionately thick layers 2 and 3 of the cerebral cortex, a feature special to humans. In these layers reside incredibly dense neuronal networks.

Without blood-borne oxygen, though, such cells only last only for about two days, so Larkum’s lab had no choice but to work around the clock during that period to get the most information from the samples. “You get the tissue very infrequently, so you’ve just got to work with what’s in front of you,” says Larkum. The team made holes in dendrites into which they could insert glass pipettes. Through these, they sent ions to stimulate the dendrites, allowing the scientists to observe their electrical behavior.

In rodents, two type of electrical spikes have been observed in dendrites: a short, one-millisecond spike with the introduction of sodium, and spikes that last 50- to 100-times longer in response to calcium.

In the human dendrites, one type of behavior was observed: super-short spikes occurring in rapid succession, one after the other. This suggests to the researchers that human neurons are “distinctly more excitable ” than rodent neurons, allowing them to successfully traverse our longer dendrites.

In addition, the human neuronal spikes — though they behaved somewhat like rodent spikes prompted by the introduction of sodium — were found to be generated by calcium, essentially the opposite of rodents.

The study also reports a second major finding. Looking to better understand how the brain utilizes these spikes, the team programmed computer models based on their findings. (The brains slices they’d examined could not, of course, be put back together and switched on somehow.)

The scientists constructed virtual neuronal networks, each of whose neurons could could be stimulated at thousands of points along its dendrites, to see how each handled so many input signals. Previous, non-human, research has suggested that neurons add these inputs together, holding onto them until the number of excitatory input signals exceeds the number of inhibitory signals, at which point the neuron fires the sum of them from its axon out into the network.

However, this isn’t what Larkum’s team observed in their model. Neurons’ output was inverse to their inputs: The more excitatory signals they received, the less likely they were to fire off. Each had a seeming “sweet spot” when it came to input strength.

What the researchers believe is going on is that dendrites and neurons may be smarter than previously suspected, processing input information as it arrives. Mayank Mehta of UC Los Angeles, who’s not involved in the research, tells LiveScience, “It doesn’t look that the cell is just adding things up — it’s also throwing things away.” This could mean each neuron is assessing the value of each signal to the network and discarding “noise.” It may also be that different neurons are optimized for different signals and thus tasks.

Much in the way that octopuses distribute decision-making across a decentralized nervous system, the implication of the new research is that, at least in humans, it’s not just the neuronal network that’s smart, it’s all of the individual neurons it contains. This would constitute exactly the kind of computational super-charging one would hope to find somewhere in the amazing human brain.

Link original: https://bigthink.com/mind-brain/human-neuron-signals?rebelltitem=1#rebelltitem1


Brain changed by caffeine in utero

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New research finds caffeine consumed during pregnancy can change important brain pathways in baby

Date:February 8, 2021Source:University of Rochester Medical CenterSummary:New research finds caffeine consumed during pregnancy can change important brain pathways that could lead to behavioral problems later in life. Researchers analyzed thousands of brain scans of nine and ten-year-olds, and revealed changes in the brain structure in children who were exposed to caffeine in utero.

New research finds caffeine consumed during pregnancy can change important brain pathways that could lead to behavioral problems later in life. Researchers in the Del Monte Institute for Neuroscience at the University of Rochester Medical Center (URMC) analyzed thousands of brain scans of nine and ten-year-olds, and revealed changes in the brain structure in children who were exposed to caffeine in utero.

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Happiness really does come for free

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People in societies where money plays a minimal role can have very high levels of happiness

Date: February 8, 2021 / Source: McGill University / Summary: Economic growth is often prescribed as a way of increasing the well-being of people in low-income countries. A new stude suggests that there may be good reason to question this assumption. The researchers found that the majority of people in societies where money plays a minimal role reported a level of happiness comparable to that found in Scandinavian countries which typically rate highest in the world.

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What is the purpose of universities?

For centuries, universities have advanced humanity toward truth. Professor Jonathan Haidt speaks to why college campuses are suddenly heading in the opposite direction.

  • In a lecture at UCCS, NYU professor Jonathan Haidt considers the ‘telos’ or purpose of universities: To discover truth.
  • Universities that prioritize the emotional comfort of students over the pursuit of truth fail to deliver on that purpose, at a great societal cost.
  • To make that point, Haidt quotes CNN contributor Van Jones: “I don’t want you to be safe ideologically. I don’t want you to be safe emotionally. I want you to be strong—that’s different.”
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Físicos dizem ter detectado o quinto elemento – a quintessência

Redação do Site Inovação Tecnológica – 27/11/2020Quintessência: Físicos dizem ter detectado o quinto elementoO observatório Planck rastreou a radiação cósmica de fundo, que os cientistas acreditam ser o “eco” do Big Bang. [Imagem: ESA/Planck]

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O retorno do éter

Uma dupla de físicos da Alemanha e do Japão acredita ter dado um passo importante para ressuscitar uma das teorias mais controversas da Física: o éter.

Até Einstein, o éter era a substância essencial a partir da qual todas as partículas e ondas eram medidas, e no qual elas se deslocavam. Mas a teoria da relatividade especial dispensou o éter. Como defender o éter significava contrapor-se à relatividade, o termo foi logo banido e criou-se muito preconceito em torno dele.

Não têm faltado tentativas de ressuscitá-lo, sendo que a versão mais moderna equivale ao chamado vácuo quântico, que descreve o “vazio” como uma sopa de partículas que surgem e desaparecem o tempo todo – para quase todos os efeitos, aceitar o vácuo quântico significa apenas rebatizar o éter.

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Su-Fi people think that in our ordinary state we are asleep / hipnotized / trance. In this state of sleep / hypnosis / trance, many of us live our entire lives without being aware that something more is possible. We imagine ourselves to be fully conscious and fully developed. This illusion prevents us from seeing our situation and, especially, ourselves as we really are.

“If a man in prison was at any time to have a chance to escape, then he must first of all realize that he is in prison.”

Sanai explained: “Humanity is asleep, concerned only with what is useless, living in a wrong world. Believing that one can excel this is only habit and usage, not religion. You have an inverted knowledge and religion if you are upside down in relation to Reality. Man is wrapping his net around himself. A lion bursts his cage asunder… ” Sanai of Afghanistan, The Walled Garden of Truth, written in 1131 A.D.

“This universe that you see, containing the human and the divine, is a unity; we are the limbs of a might body. Nature brought us to birth as kin, since it generated us all from the same materials and for the same purposes, endowing us with affection for one another and making us companionable. Nature establishes fairness and justice. According to nature’s dispensation, it is worse to harm than to be harmed. On the basis of nature’s command, let our hands be available to help whenever necessary. Let this verse be in your heart and in your mouth:

I am a human being, I regard nothing human as foreign to me. Let us hold things in common, as we are born for the common good. Our companionship is just like an arch, which would collapse without the stones’ mutual support to hold it up.”

Seneca, letter 95.



This brain balancing act allows consciousness

Two types of thinking have a time-sharing deal going on in your brain.

  • Your DMN and DAT neural networks cooperate by staying out of each other’s way.
  • FMRI scans reveal a surprising temporal dance.
  • When both systems are at the same activity level, boom, you’re unconscious.

While consciousness remains “the hard problem” — as in what exactly is it? Where is it? — a new study published in Science Advances sheds surprising light on how the brain switches us from conscious to unconscious states and vice versa. It has something to do with an imbalance between two neural systems. In fact, consciousness requires that imbalance.

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