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Your mental dictionary is part of what makes you unique − here’s how your brain stores and retrieves words

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Your mental dictionary is part of what makes you unique − here’s how your brain stores and retrieves words

Your brain processes letters, words, sounds, semantics and grammar at breakneck speed.
StudioM1/iStock via Getty Images Plus

Nichol Castro, University at Buffalo

The days of a dictionary on your bookshelf are numbered. But that’s OK, because everyone already walks around with a dictionary – not the one on your phone, but the one in your head.

Just like a physical dictionary, your mental dictionary contains information about words. This includes the letters, sounds and meaning, or semantics, of words, as well as information about parts of speech and how you can fit words together to form grammatical sentences. Your mental dictionary is also like a thesaurus. It can you connect words and see how they might be similar in meaning, sound or spelling.

As a researcher who studies word retrieval, or how you quickly and accurately pull words out of your memory to communicate, I’m intrigued by how words are organized in our mental dictionaries. Everyone’s mental dictionary is a little bit different. And I’m even more intrigued by how we can restore the content of our mental dictionaries or improve our use of them, particularly for those who have language disorders.

Language is part of what makes humans special, and I believe everyone deserves the to use their words with others.

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Your mental dictionary

While a physical dictionary is helpful for shared knowledge, your personal mental dictionary is customized based on your individual experiences. What words are in my mental dictionary might overlap with the mental dictionary of someone else who also speaks the same language, but there will also be a lot of differences between the content of our dictionaries.

You add words to your mental dictionary through your educational, occupational, cultural and other experiences. This customization also means that the size of mental dictionaries is a little bit different from person to person and varies by age. Researchers found that the average 20-year-old American English speaker knows about 42,000 unique words, and this number grows to about 48,000 by age 60. Some people will have even larger vocabularies.

By now, you might be envisioning your mental dictionary as a book with pages of words in alphabetical order you can flip through as needed. While this visual analogy is helpful, there is a lot of debate about how mental dictionaries are organized. Many scholars agree that it’s probably not like an alphabetized book.

Scientists created an interactive map of which brain respond to hearing different words.

One widely rejected theory, the grandmother cell theory, suggests that each concept is encoded by a single neuron. This implies that you would have a neuron for every word that you know, “grandmother.”

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While not accepted as accurate, the aspect of the grandmother cell theory suggesting that certain parts of the brain are more important for some types of information than others is likely true. For example, the left temporal lobe on the side of your brain has many regions that are important for language processing, including word retrieval and production. Rather than a single neuron responsible for processing a concept, a model called parallel distributed processing proposes that large networks of neurons across the brain work together to bring about word knowledge when they fire together.

For example, when I say the word “dog,” there are lots of different aspects of the word that your brain is retrieving, even if unconsciously. You might be thinking about what a dog smells like after being out in the rain, what a dog sounds like when it barks, or what a dog feels like when you pet it. You might be thinking about a specific dog you grew up with, or you might have a variety of emotions about dogs based on your past experiences with them. All of these different features of “dog” are processed in slightly different parts of your brain.

Using your mental dictionary

One reason why your mental dictionary can’t be like a physical dictionary is that it is dynamic and quickly accessed.

Your brain’s ability to retrieve a word is very fast. In one study, researchers mapped the time course of word retrieval among 24 college by recording their brain activity while they named pictures. They found evidence that participants selected words within 200 milliseconds of seeing the image. After word selection, their brain continued to information about that word, like what sounds are needed to say that chosen word and ignoring related words. This is why you can retrieve words with such speed in real-time conversations, often so quickly that you give little conscious attention to that process.

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Until … you have a in word retrieval. One common failure in word retrieval is called the tip-of-the-tongue phenomenon. It’s the feeling when you know what word you want to use but are unable to find it in that moment. You might even know specific details about the word you want, like other words with similar meaning or maybe the first letter or sound of that word. With enough time, the word you wanted might pop into your mind.

These tip-of-the-tongue experiences are a normal part of human language experience across the life span, and they increase as you grow older. One proposed reason for this increase is that they’re due to an age-related disruption in the ability to turn on the right sounds needed to say the selected word.

Speech therapist showing young patient how to roll tongue in forming a word
Speech-language pathologists help improve on their word retrieval abilities and speech.
fizkes/iStock via Getty Images Plus

For some people, though, tip-of-the-tongue experiences and other speech errors can be quite impairing. This is commonly seen in aphasia, a language disorder that often occurs after injury to the language centers of the brain, such as stroke, or neurodegeneration, such as dementia. People with aphasia often have difficulty with word retrieval.

Fortunately, there are treatments available that can help someone improve their word retrieval abilities. For example, semantic feature analysis focuses on strengthening the semantic relationships between words. There are also treatments like phonomotor treatment that focus on strengthening the selection and production of speech sounds needed for word production. There are even apps that remotely provide word retrieval therapy on phones or computers.

The next time you have a conversation with someone, take a moment to reflect on why you chose the specific words you did. Remember that the words you use and the mental dictionary you have are part of what make you and your voice unique.The Conversation

Nichol Castro, Assistant Professor of Communicative Disorders and Sciences, University at Buffalo

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The Conversation

a double shot of US history

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theconversation.com – Kyle G. Volk, Professor of History, University of Montana – 2024-09-16 07:28:46

Having a beer in Raceland, La.

Russell Lee for Farm Security Administration/WPA

Kyle G. Volk, University of Montana

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Text saying: Uncommon Courses, from The Conversation

Uncommon Courses is an occasional from U.S. highlighting unconventional approaches to teaching.

Title of course:

“Intoxication Nation: Alcohol in American History”

What prompted the idea for the course?

I wanted to get students about studying the past by learning about something that is very much a part of their own lives.

Alcohol – somewhat surprisingly to me at first – featured prominently in my own research on minority rights and U.S. democracy in the mid-19th century. As a result, I knew quite a bit about the temperance movement and conflicts over prohibition during that period. Designing this course me to broaden my expertise.

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What does the course explore?

Prohibition is a must-do subject. Students expect it. But I several hundred years of history: from the 17th-century invention of rum – as a byproduct of sugar produced by enslaved people – to the rise of craft beer and craft spirits in the 21st century.

A faded poster with an illustration of a person about to smash a huge bottle of alcohol, and the message 'Close the saloons' at the top.

A temperance poster from the World War I era.

Office of Naval Records and Library via National Archives Catalog

Along the way, I’m thrilled when students get excited about details that allow them to a more complicated historical cocktail. For example, they learn why white women’s production of hard cider was crucial to the survival of colonial Virginia. The short answer: Potable water was in short supply, alcoholic drinks were far healthier, and white men – and their indentured and enslaved workforce – were busy raising tobacco. It fell to women to turn fruit into salvation.

Why is this course relevant now?

Alcohol remains a big and almost inescapable part of American society. But of late, Americans have been drinking differently – and thinking about drinking differently.

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Examples abound. Alcohol producers, we learn, now face competition from legalized weed. Drinking l evels rose during the COVID-19 pandemic, yet interest is declining among Gen Zers. The “wine mom” culture that brought some mothers together now faces mounting criticism.

And, of course, there’s the never-ending debate about the health benefits and risks of alcohol. Of late, the risks seem to be dominating headlines.

What’s a critical lesson from the course?

Alcohol has been a highly controversial, central aspect of the American experience, shaping virtually all sectors of our society – political and constitutional, business and economic, social and cultural.

What materials does the course feature?

What will the course prepare students to do?

Like any history course, this one aims to develop student’s analytical, written, research and verbal skills. In lots of ways, the topic is just a tool to get students to grow their brains. But I also seek to grow students’ critical awareness of the place of alcohol in their own lives. The course has also informed students’ paths after graduation – some who wound up working in the alcohol industry or recovery .The Conversation

Kyle G. Volk, Professor of History, University of Montana

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Sunflowers make small moves to maximize their Sun exposure − physicists can model them to predict how they grow

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theconversation.com – Chantal Nguyen, Postdoctoral Associate at the BioFrontiers Institute, of Colorado Boulder – 2024-09-13 07:31:40

Sunflowers use tiny movements to follow the Sun’s path throughout the day.

AP Photo/Charlie Riedel

Chantal Nguyen, University of Colorado Boulder

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Most of us aren’t spending our days watching our houseplants grow. We see their signs of only occasionally – a new leaf unfurled, a stem leaning toward the window.

But in the summer of 1863, Charles Darwin lay ill in bed, with nothing to do but watch his plants so closely that he could detect their small movements to and fro. The tendrils from his cucumber plants swept in circles until they encountered a stick, which they proceeded to twine around.

“I am getting very much amused by my tendrils,” he wrote.

This amusement blossomed into a decadeslong fascination with the little-noticed world of plant movements. He compiled his detailed observations and experiments in a 1880 book called “The Power of Movement in Plants.”

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A zig-zagging line showing the movement of a leaf.

A diagram tracking the circumnutation of a leaf over three days.

Charles Darwin

In one study, he traced the motion of a carnation leaf every few hours over the course of three days, revealing an irregular looping, jagged path. The swoops of cucumber tendrils and the zags of carnation leaves are examples of inherent, ubiquitous plant movements called circumnutations – from the Latin circum, meaning circle, and nutare, meaning to nod.

Circumnutations vary in size, regularity and timescale across plant species. But their exact function remains unclear.

I’m a physicist interested in understanding collective behavior in living . Like Darwin, I’m captivated by circumnutations, since they may underlie more complex phenomena in groups of plants.

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Sunflower patterns

A 2017 study revealed a fascinating observation that got my colleagues and me wondering about the role circumnutations could play in plant growth patterns. In this study, researchers found that sunflowers grown in a dense row naturally formed a near-perfect zigzag pattern, with each plant leaning away from the row in alternating directions.

This pattern the plants to avoid shade from their neighbors and maximize their exposure to sunlight. These sunflowers flourished.

Researchers then planted some plants at the same density but constrained them so that they could grow only upright without leaning. These constrained plants produced less oil than the plants that could lean and get the maximum amount of sun.

While farmers can’t grow their sunflowers quite this close together due to the potential for disease spread, in the future they may be able to use these patterns to up with new planting strategies.

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Self-organization and randomness

This spontaneous pattern formation is a neat example of self-organization in nature. Self-organization refers to when initially disordered systems, such as a jungle of plants or a swarm of bees, achieve order without anything controlling them. Order emerges from the interactions between individual members of the system and their interactions with the .

Somewhat counterintuitively, noise – also called randomness – facilitates self-organization. Consider a colony of ants.

Ants secrete pheromones behind them as they crawl toward a food source. Other ants find this food source by the pheromone trails, and they further reinforce the trail they took by secreting their own pheromones in turn. Over time, the ants converge on the best path to the food, and a single trail prevails.

But if a shorter path were to become possible, the ants would not necessarily find this path just by following the existing trail.

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If a few ants were to randomly deviate from the trail, though, they might stumble onto the shorter path and create a new trail. So this randomness injects a spontaneous change into the ants’ system that allows them to explore alternative scenarios.

Eventually, more ants would follow the new trail, and soon the shorter path would prevail. This randomness helps the ants adapt to changes in the environment, as a few ants spontaneously seek out more direct ways to their food source.

A group of honeybees spread out standing on honeycomb.

Beehives are an example of self-organization in nature.

Martin Ruegner/Stone via Getty Images

In biology, self-organized systems can be found at a range of scales, from the patterns of proteins inside cells to the socially complex colonies of honeybees that collectively build nests and forage for nectar.

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Randomness in sunflower self-organization

So, could random, irregular circumnutations underpin the sunflowers’ self-organization?

My colleagues and I set out to explore this question by following the growth of young sunflowers we planted in the lab. Using cameras that imaged the plants every five minutes, we tracked the movement of the plants to see their circumnutatory paths.

We saw some loops and spirals, and lots of jagged movements. These ultimately appeared largely random, much like Darwin’s carnation. But when we placed the plants together in rows, they began to move away from one another, forming the same zigzag configurations that we’d seen in the previous study.

Five plants and a diagram showing loops and jagged lines that represent small movements made by the plants.

Tracking the circumnutations made by young sunflower plants.

Chantal Nguyen

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We analyzed the plants’ circumnutations and found that at any given time, the direction of the plant’s motion appeared completely independent of how it was moving about half an hour earlier. If you measured a plant’s motion once every 30 minutes, it would appear to be moving in a completely random way.

We also measured how much the plant’s leaves grew over the course of two weeks. By putting all of these results together, we sketched a picture of how a plant moved and grew on its own. This information allowed us to computationally model a sunflower and simulate how it behaves over the course of its growth.

A sunflower model

We modeled each plant simply as a circular crown on a stem, with the crown expanding according to the growth rate we measured experimentally. The simulated plant moved in a completely random way, taking a “step” every half hour.

We created the model sunflowers with circumnutations of lower or higher intensity by tweaking the step sizes. At one end of the spectrum, sunflowers were much more likely to take tiny steps than big ones, leading to slow, minimal movement on average. At the other end were sunflowers that are equally as likely to take large steps as small steps, resulting in highly irregular movement. The real sunflowers we observed in our experiment were somewhere in the middle.

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Plants require light to grow and have evolved the ability to detect shade and alter the direction of their growth in response.

We wanted our model sunflowers to do the same thing. So, we made it so that two plants that get too close to each other’s shade begin to lean away in opposite directions.

Finally, we wanted to see whether we could replicate the zigzag pattern we’d observed with the real sunflowers in our model.

First, we set the model sunflowers to make small circumnutations. Their shade avoidance responses pushed them away from each other, but that wasn’t enough to produce the zigzag – the model plants stayed stuck in a line. In physics, we would call this a “frustrated” system.

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Then, we set the plants to make large circumnutations. The plants started moving in random patterns that often brought the plants closer together rather than farther apart. Again, no zigzag pattern like we’d seen in the field.

But when we set the model plants to make moderately large movements, similar to our experimental measurements, the plants could self-organize into a zigzag pattern that gave each sunflower optimal exposure to light.

So, we showed that these random, irregular movements helped the plants explore their surroundings to find desirable arrangements that benefited their growth.

Plants are much more dynamic than people give them credit for. By taking the time to follow them, scientists and farmers can unlock their secrets and use plants’ movement to their advantage.The Conversation

Chantal Nguyen, Postdoctoral Associate at the BioFrontiers Institute, University of Colorado Boulder

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Endometriosis pain leads to missed school and work in two-thirds of women with the condition, new study finds

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theconversation.com – Rasha Al-Lami, Researcher in Women’s Health, Yale – 2024-09-13 07:30:43

Endometriosis affects about 10% of reproductive-age women worldwide.

Xavier Lorenzo/Moment via Getty Images

Rasha Al-Lami, Yale University

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More than two-thirds of women with endometriosis missed school or work due to pain from the , in a study of more than 17,000 women between the ages of 15 and 44 in the U.S. That is a key finding of new research published in the Journal of Endometriosis and Uterine Disorders.

Our study also found that Black and Hispanic women were less likely to be diagnosed with endometriosis with white women. Interestingly, women who identified as part of the LGBTQ community had a higher likelihood of receiving an endometriosis diagnosis than heterosexual women.

We used data from the National Health and Nutrition Examination Survey, which is administered by the Centers for Disease Control and Prevention, for the period 2011 to 2019. The survey data use adjusted weights to account for the racial composition of U.S. society, meaning our sample of 17,619 women represents 51,981,323 women of the U.S. population.

We specifically examined factors related to quality of life, such as poverty, education and functional impairment, as well as race and sexual orientation.

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I am a physician-scientist and a researcher in women’s health, working together with specialists in OB-GYN from Yale and the University of .

Why it matters

Endometriosis is a chronic, often painful condition that affects approximately 10% of reproductive-age women worldwide. It occurs when tissues that would normally line the inner surface of the uterus instead occur outside the uterus, such as on the ovaries or even in distant organs such as the lungs or brain. These abnormally located lesions respond to hormonal changes during the menstrual cycle, causing pain when stimulated by the hormones that regulate the menstrual cycle.

Our study sheds light on how endometriosis, despite its prevalence, remains underdiagnosed and underresearched. We found that 6.4% of reproductive-age women in the U.S. had an endometriosis diagnosis. More than 67% reported missed work or school, or been unable to perform activities, due to pain associated with endometriosis.

Our study highlights disparities in the diagnosis and management of endometriosis among different racial groups. Black women had 63% lower odds of getting an endometriosis diagnosis, and Hispanic women had 55% lower odds compared with non-Hispanic white women. This disparity may reflect historical biases in , pointing to the need for more equitable practices.

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In addition, our study underscores the importance of considering women’s health across diverse population subgroups, with particular attention to sexual orientation. We found that non-heterosexual lesbian, gay, bisexual, transgender and queer women had 54% higher odds of receiving an endometriosis diagnosis compared with straight women. Our study was the first to examine endometriosis likelihood among non-heterosexual women at the national level in the U.S.

We found no significant association between endometriosis and other quality-of-life indicators such as poverty, education or employment status, which suggests that the condition affects women across various socioeconomic backgrounds.

A common theory about the cause of endometriosis is that women have menstrual blood that seeds outside of the uterus, but recent research supports inflammatory causes.

What other research is being done

Our work adds to the growing body of evidence that Black women are less likely to be diagnosed with endometriosis and that their reported pain symptoms are often overlooked.

Explanations for this inequity include health care bias against minority women and limited access to medical care among Black women. Research also shows that many medical professionals as well as medical students and believe that Black women have a lower pain threshold compared with the white population.

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This is another possible reason that pain symptoms among Black women with endometriosis get neglected. Researchers from the U.K reported the same findings, attributing these disparities to systemic bias and inequitable medical care.

Another study estimates that the lifetime costs associated with having endometriosis are about US$27,855 per year per patient in the U.S., costing the country about $22 annually on health care expenditures.The Conversation

Rasha Al-Lami, Researcher in Women’s Health, Yale University

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