Posts tagged cognition
Posts tagged cognition
To evaluate school quality, states require students to take standardized tests; in many cases, passing those tests is necessary to receive a high-school diploma. These high-stakes tests have also been shown to predict students’ future educational attainment and adult employment and income.
Such tests are designed to measure the knowledge and skills that students have acquired in school — what psychologists call “crystallized intelligence.” However, schools whose students have the highest gains on test scores do not produce similar gains in “fluid intelligence” — the ability to analyze abstract problems and think logically — according to a new study from MIT neuroscientists working with education researchers at Harvard University and Brown University.
In a study of nearly 1,400 eighth-graders in the Boston public school system, the researchers found that some schools have successfully raised their students’ scores on the Massachusetts Comprehensive Assessment System (MCAS). However, those schools had almost no effect on students’ performance on tests of fluid intelligence skills, such as working memory capacity, speed of information processing, and ability to solve abstract problems.
“Our original question was this: If you have a school that’s effectively helping kids from lower socioeconomic environments by moving up their scores and improving their chances to go to college, then are those changes accompanied by gains in additional cognitive skills?” says John Gabrieli, the Grover M. Hermann Professor of Health Sciences and Technology, professor of brain and cognitive sciences, and senior author of a forthcoming Psychological Science paper describing the findings.
Instead, the researchers found that educational practices designed to raise knowledge and boost test scores do not improve fluid intelligence. “It doesn’t seem like you get these skills for free in the way that you might hope, just by doing a lot of studying and being a good student,” says Gabrieli, who is also a member of MIT’s McGovern Institute for Brain Research.
This study grew out of a larger effort to find measures beyond standardized tests that can predict long-term success for students. “As we started that study, it struck us that there’s been surprisingly little evaluation of different kinds of cognitive abilities and how they relate to educational outcomes,” Gabrieli says.
The data for the Psychological Science study came from students attending traditional, charter, and exam schools in Boston. Some of those schools have had great success improving their students’ MCAS scores — a boost that studies have found also translates to better performance on the SAT and Advanced Placement tests.
The researchers calculated how much of the variation in MCAS scores was due to the school that students attended. For MCAS scores in English, schools accounted for 24 percent of the variation, and they accounted for 34 percent of the math MCAS variation. However, the schools accounted for very little of the variation in fluid cognitive skills — less than 3 percent for all three skills combined.
In one example of a test of fluid reasoning, students were asked to choose which of six pictures completed the missing pieces of a puzzle — a task requiring integration of information such as shape, pattern, and orientation.
“It’s not always clear what dimensions you have to pay attention to get the problem correct. That’s why we call it fluid, because it’s the application of reasoning skills in novel contexts,” says Amy Finn, an MIT postdoc and lead author of the paper.
Even stronger evidence came from a comparison of about 200 students who had entered a lottery for admittance to a handful of Boston’s oversubscribed charter schools, many of which achieve strong improvement in MCAS scores. The researchers found that students who were randomly selected to attend high-performing charter schools did significantly better on the math MCAS than those who were not chosen, but there was no corresponding increase in fluid intelligence scores.
However, the researchers say their study is not about comparing charter schools and district schools. Rather, the study showed that while schools of both types varied in their impact on test scores, they did not vary in their impact on fluid cognitive skills.
The researchers plan to continue tracking these students, who are now in 10th grade, to see how their academic performance and other life outcomes evolve. They have also begun to participate in a new study of high school seniors to track how their standardized test scores and cognitive abilities influence their rates of college attendance and graduation.
Implications for education
Gabrieli notes that the study should not be interpreted as critical of schools that are improving their students’ MCAS scores. “It’s valuable to push up the crystallized abilities, because if you can do more math, if you can read a paragraph and answer comprehension questions, all those things are positive,” he says.
He hopes that the findings will encourage educational policymakers to consider adding practices that enhance cognitive skills. Although many studies have shown that students’ fluid cognitive skills predict their academic performance, such skills are seldom explicitly taught.
“Schools can improve crystallized abilities, and now it might be a priority to see if there are some methods for enhancing the fluid ones as well,” Gabrieli says.
Some studies have found that educational programs that focus on improving memory, attention, executive function, and inductive reasoning can boost fluid intelligence, but there is still much disagreement over what programs are consistently effective.
A new study led by University of Kentucky researchers suggests that a diet low in vitamin D causes damage to the brain.
In addition to being essential for maintaining bone health, newer evidence shows that vitamin D serves important roles in other organs and tissue, including the brain. Published in Free Radical Biology and Medicine, the UK study showed that middle-aged rats that were fed a diet low in vitamin D for several months developed free radical damage to the brain, and many different brain proteins were damaged as identified by redox proteomics. These rats also showed a significant decrease in cognitive performance on tests of learning and memory.
"Given that vitamin D deficiency is especially widespread among the elderly, we investigated how during aging from middle-age to old-age how low vitamin D affected the oxidative status of the brain," said lead author on the paper Allan Butterfield, professor in the UK Department of Chemistry, director of the Center of Membrane Sciences, faculty of Sanders-Brown Center on Aging, and director of the Free Radical Biology in Cancer Core of the Markey Cancer Center. “Adequate vitamin D serum levels are necessary to prevent free radical damage in brain and subsequent deleterious consequences."
Previously, low levels of vitamin D have been associated with Alzheimer’s disease, and it’s also been linked to the development of certain cancers and heart disease. In both the developed world and in areas of economic hardship where food intake is not always the most nutritious, vitamin D levels in humans are often low, particularly in the elderly population. Butterfield recommends persons consult their physicians to have their vitamin D levels determined, and if low that they eat foods rich in vitamin D, take vitamin D supplements, and/or get at least 10-15 minutes of sun exposure each day to ensure that vitamin D levels are normalized and remain so to help protect the brain.
A new brain connectivity study from Penn Medicine published today in the Proceedings of National Academy of Sciences found striking differences in the neural wiring of men and women that’s lending credence to some commonly-held beliefs about their behavior.
In one of the largest studies looking at the “connectomes” of the sexes, Ragini Verma, PhD, an associate professor in the department of Radiology at the Perelman School of Medicine at the University of Pennsylvania, and colleagues found greater neural connectivity from front to back and within one hemisphere in males, suggesting their brains are structured to facilitate connectivity between perception and coordinated action. In contrast, in females, the wiring goes between the left and right hemispheres, suggesting that they facilitate communication between the analytical and intuition.
“These maps show us a stark difference—and complementarity—in the architecture of the human brain that helps provide a potential neural basis as to why men excel at certain tasks, and women at others,” said Verma.
For instance, on average, men are more likely better at learning and performing a single task at hand, like cycling or navigating directions, whereas women have superior memory and social cognition skills, making them more equipped for multitasking and creating solutions that work for a group. They have a mentalistic approach, so to speak.
Past studies have shown sex differences in the brain, but the neural wiring connecting regions across the whole brain that have been tied to such cognitive skills has never been fully shown in a large population.
In the study, Verma and colleagues, including co-authors Ruben C. Gur, PhD, a professor of psychology in the department of Psychiatry, and Raquel E. Gur, MD, PhD, professor of Psychiatry, Neurology and Radiology, investigated the gender-specific differences in brain connectivity during the course of development in 949 individuals (521 females and 428 males) aged 8 to 22 years using diffusion tensor imaging (DTI). DTI is water-based imaging technique that can trace and highlight the fiber pathways connecting the different regions of the brain, laying the foundation for a structural connectome or network of the whole brain.
This sample of youths was studied as part of the Philadelphia Neurodevelopmental Cohort, a National Institute of Mental Health-funded collaboration between the University of Pennsylvania Brain Behavior Laboratory and the Center for Applied Genomics at the Children’s Hospital of Philadelphia.
The brain is a roadmap of neural pathways linking many networks that help us process information and react accordingly, with behavior controlled by several of these sub-networks working in conjunction.
In the study, the researchers found that females displayed greater connectivity in the supratentorial region, which contains the cerebrum, the largest part of the brain, between the left and right hemispheres. Males, on the other hand, displayed greater connectivity within each hemisphere.
By contrast, the opposite prevailed in the cerebellum, the part of the brain that plays a major role in motor control, where males displayed greater inter-hemispheric connectivity and females displayed greater intra-hemispheric connectivity.
These connections likely give men an efficient system for coordinated action, where the cerebellum and cortex participate in bridging between perceptual experiences in the back of the brain, and action, in the front of the brain, according to the authors. The female connections likely facilitate integration of the analytic and sequential processing modes of the left hemisphere with the spatial, intuitive information processing modes of the right side.
The authors observed only a few gender differences in the connectivity in children younger than 13 years, but the differences were more pronounced in adolescents aged 14 to 17 years and young adults older than 17.
The findings were also consistent with a Penn behavior study, of which this imaging study was a subset of, that demonstrated pronounced sexual differences. Females outperformed males on attention, word and face memory, and social cognition tests. Males performed better on spatial processing and sensorimotor speed. Those differences were most pronounced in the 12 to 14 age range.
“It’s quite striking how complementary the brains of women and men really are,” said Dr. Ruben Gur. “Detailed connectome maps of the brain will not only help us better understand the differences between how men and women think, but it will also give us more insight into the roots of neurological disorders, which are often sex related.”
Next steps are to quantify how an individual’s neural connections are different from the population; identify which neural connections are gender specific and common in both; and to see if findings from functional magnetic resonance imaging (fMRI) studies fall in line with the connectome data.
Scientists have long suspected that corvids – the family of birds including ravens, crows and magpies – are highly intelligent. Now, Tübingen neurobiologists Lena Veit und Professor Andreas Nieder have demonstrated how the brains of crows produce intelligent behavior when the birds have to make strategic decisions. Their results are published in the latest edition of Nature Communications.
Crows are no bird-brains. Behavioral biologists have even called them “feathered primates” because the birds make and use tools, are able to remember large numbers of feeding sites, and plan their social behavior according to what other members of their group do. This high level of intelligence might seem surprising because birds’ brains are constructed in a fundamentally different way from those of mammals, including primates – which are usually used to investigate these behaviors.
The Tübingen researchers are the first to investigate the brain physiology of crows’ intelligent behavior. They trained crows to carry out memory tests on a computer. The crows were shown an image and had to remember it. Shortly afterwards, they had to select one of two test images on a touchscreen with their beaks based on a switching behavioral rules. One of the test images was identical to the first image, the other different. Sometimes the rule of the game was to select the same image, and sometimes it was to select the different one. The crows were able to carry out both tasks and to switch between them as appropriate. That demonstrates a high level of concentration and mental flexibility which few animal species can manage – and which is an effort even for humans.
The crows were quickly able to carry out these tasks even when given new sets of images. The researchers observed neuronal activity in the nidopallium caudolaterale, a brain region associated with the highest levels of cognition in birds. One group of nerve cells responded exclusively when the crows had to choose the same image – while another group of cells always responded when they were operating on the “different image” rule. By observing this cell activity, the researchers were often able to predict which rule the crow was following even before it made its choice.
The study published in Nature Communications provides valuable insights into the parallel evolution of intelligent behavior. “Many functions are realized differently in birds because a long evolutionary history separates us from these direct descendants of the dinosaurs,” says Lena Veit. “This means that bird brains can show us an alternative solution out of how intelligent behavior is produced with a different anatomy.” Crows and primates have different brains, but the cells regulating decision-making are very similar. They represent a general principle which has re-emerged throughout the history of evolution. “Just as we can draw valid conclusions on aerodynamics from a comparison of the very differently constructed wings of birds and bats, here we are able to draw conclusions about how the brain works by investigating the functional similarities and differences of the relevant brain areas in avian and mammalian brains,” says Professor Andreas Nieder.
Most songbirds learn their songs from an adult model, mostly from the father. However, there are relatively large differences in the accuracy how these songs are copied. Researchers from the Max Planck Institute for Ornithology in Seewiesen now found in juvenile zebra finches a possible mechanism that is responsible for the differences in the intensity of song learning. They provided the nerve growth factor “BDNF” to the song control system in the brain. With this treatment the learning ability in juvenile males could be enhanced in such a way that they were able to copy the songs of the father as good as it had been observed in the best learners in a zebra finch nest.
The improvement of cognitive abilities plays an important role in the therapy of neurological and psychiatric diseases. In this context research focusses more and more on the protein BDNF (Brain Derived Neurotrophic Factor). BDNF is mainly responsible for the preservation, growth and differentiation of nerve cells. Moreover, from experiments in mice it is known that BDNF enhances the ability to solve complex cognitive tasks.
In a learning experiment with zebra finches, researchers from the Max Planck Institute for Ornithology in Seewiesen in collaboration with scientists from the Free University of Amsterdam could now show for the first time in songbirds that BDNF acts as cognitive enhancer. They investigated zebra finch brother pairs that grew up with their genetic parents. In this setup juvenile birds will readily learn the songs from their fathers. However there are differences in the intensity of song learning among siblings of the same age. The worst learners have only a similarity of 20% with their fathers’ songs, whereas the best learners copy almost the entire songs of their fathers.
By now knowing the normal distribution of the learned songs within a zebra finch nest, as a next step the researchers were able to investigate the impact of BDNF on song learning. In one of the two brothers they enhanced the expression of BDNF in the song control system in the brain while the other brother did not get such a treatment. By analysing the songs the researchers found that those sons that received more BDNF had a higher similarity with the song of their fathers compared to normally reared juveniles. Remarkably, the learning efficiency in the BDNF-treated birds was as high as it has been previously observed in the best learners within the nest. This was due to an earlier onset of syllable copying in BDNF-treated birds and these birds also copied more and sang fewer improvised syllables. Therefore it is likely that the presence of BDNF in the song control system could correct possible inaccuracies in the song learning process, state the scientists around Manfred Gahr, who is the senior author of the study.
In a breakthrough for understanding brain evolution, neuroscientists have shown that differences between primate brains - from the tiny marmoset to human – can be largely explained as consequences of the same genetic program.
In research published in the Journal of Neuroscience, Professor Marcello Rosa and his team at Monash University’s School of Biomedical Sciences and colleagues at Universidade Federal do Rio de Janeiro, in Brazil, used computer modelling to demonstrate that the substantial enlargement of some areas of the human brain, vital to advanced cognition, reflected a consistent pattern that is seen across primate species of all sizes.
This finding suggests how the neural circuits responsible for traits that we consider uniquely human – such as the ability to plan, make complex decisions and speak – could have emerged simply as a natural consequence of the evolution of larger brains.
“We have known for a long time that certain areas of the human brain are much larger than one would expect based on how monkey brains are organised,” Professor Rosa said.
“What no one had realised is that this selective enlargement is part of a trend that has been present since the dawn of primates.”
Using publicly available brain maps, MRI imaging data and modelling software, the neuroscientists compared the sizes of different brain areasin humans and three monkey species: marmosets, capuchins and macaques. They found that two regions, the lateral prefrontal cortex and the temporal parietal junction, expand disproportionally to the rest of the brain.
The prefrontal cortex is related to long term planning, personality expression, decision-making, and behaviour modification. The temporal parietal junction is related to self-awareness and self-other distinction.
Lead author Tristan Chaplin, from the Department of Physiology will commence his PhD next year. He said the findings showed that those areas of the brain grew disproportionately in a predictable way.
“We found that the larger the brain is, the larger these areas get,” Tristan said.
“When you go from a small to big monkey - the marmoset to macaque - the prefrontal cortex and temporal parietal junction get larger relative to the rest of the cortex, and we see the same thing again when you compare macaques to humans.”
“This trend argues against the view that specific human mutations gave us these larger areas and advanced cognition and behaviour, but are a consequence of what happens in development when you grow a larger brain,” Tristan said.
Professor Rosa said the pattern held for primate species that evolved completely separately.
"If you compare the capuchin of South America and the macaque of Asia, their brains are almost identical, although they developed on opposite sides of the world. They both reflect the genetic plan of how a primate brain grows," Professor Rosa said.
This is the first computational comparative study conducted across several primate species. Tristan now hopes, in collaboration with zoos, to check if our closest primate relatives, the chimpanzees and gorillas, also have brain areas organised as his theory predicts.
About 70 percent of a person’s intelligence can be explained by their DNA — and those genetic influences only get stronger with age, according to new research from The University of Texas at Austin.
The study, authored by psychology researchers Elliot Tucker-Drob, Daniel Briley and Paige Harden, shows how genes can be stimulated or suppressed depending on the child’s environment and could help bridge the achievement gap between rich and poor students. The findings are published online in Current Directions in Psychological Science.
To investigate the underlying mechanisms at work, Tucker-Drob and his colleagues analyzed data from several studies tracking the cognitive ability and environmental circumstances of twin and sibling pairs. According to the findings, genetic factors account for 80 percent of cognition for children in economically advantaged households. Yet disadvantaged children – who rank lower in cognitive performance across the board – show almost no progress attributable to their genetic makeup.
This doesn’t mean disadvantaged children are genetically inferior. Instead, they have less high-quality opportunities, such as learning resources and parental involvement, to reach their genetic potential, Tucker-Drob says.
“Genetic influences on cognitive ability are maximized when people are free to select their own learning experiences,” says Tucker-Drob, who is an assistant professor of psychology. “We were born with blueprints; the question is how are we using our experiences to build upon our genetic makeup?”
In a related study, Daniel Briley, a psychology doctoral student, examined how genetic and environmental influences on cognition change over time. Using meta-analytic procedures — the statistical methods used to analyze and combine results from previous, related literature — Briley examined genetic and environmental influences on cognition in twin and sibling pairs from infancy to adolescence.
According to his findings, published in the July issue of Psychological Science, genes influencing cognition become activated during the first decade of life and accelerate over time. The results emphasize the importance of early literacy and education during the first decade of life.
“As children get older, their parents and teachers give them increasing autonomy to do their homework to the best of their ability, pay attention in class, and choose their peer group,” says Briley. “Each of these behaviors likely influences their academic development. If these types of behaviors are influenced by genes, then it would explain why the heritability of cognitive ability increases as children age.”
Tucker-Drob says this research highlights the possibilities for bridging the achievement gap between the rich and poor.
“The conventional view is that genes place an upper limit on the effects of social intervention on cognitive development,” says Tucker-Drob. “This research suggests the opposite. As social, educational and economic opportunities increase in a society, more children will have access to the resources they need to maximize their genetic potentials.”
During pregnancy, the bone hormone osteocalcin is produced by the mother; it crosses the placenta, to reach the fetus, where it promotes the formation of the hippocampus and the development of spatial learning and memory. Postnatally, osteocalcin crosses the blood-brain barrier (BBB), to act in various regions of the brain, including the hippocampus, where it causes changes in brain chemistry that help prevent anxiety and depression and improve spatial learning and memory.
Image credit: Gerard Karsenty, MD, PhD and Franck Oury, PhD/Columbia University Medical Center
Findings could lead to new treatments for memory loss, anxiety, and depression
Researchers from Columbia University Medical Center (CUMC) have found that the skeleton, acting through the bone-derived hormone osteocalcin, exerts a powerful influence on prenatal brain development and cognitive functions such as learning, memory, anxiety, and depression in adult mice. Findings from the mouse study could lead to new approaches to the prevention and treatment of neurologic disorders. The study was published today in the online edition of Cell.
“The brain is commonly viewed as an organ that influences other organs and parts of the body, but less often as the recipient of signals coming from elsewhere, least of all, the bones,” said study leader Gerard Karsenty, MD, PhD, Paul A. Marks Professor of Genetics and Development, professor of medicine, and chair of the Department of Genetics and Development.
“In an earlier study, we showed that the brain is a powerful inhibitor of bone mass accrual,” he said. “This effect was so powerful that it immediately raised the question, ‘Does the bone signal back to the brain to limit this negative influence?’ ‘If so, what signals does it use and how do they work?’”
Dr. Karsenty suspected that osteocalcin, a hormone recently identified by his lab and secreted by osteoblasts, might be involved in such bone-to-brain signaling. Earlier studies had shown that osteocalcin affects a variety of processes, such as energy expenditure, glucose balance, and male fertility. “Since most hormones influence a range of physiological processes, it was reasonable to assume that the endocrine functions of osteocalcin were even broader than what was already known,” he said.
To determine whether osteocalcin did indeed play a role in the brain, Dr. Karsenty and his team studied “osteocalcin-null” mice (mice that have been genetically engineered to not produce any osteocalcin). Using these mice, they were able to show unambiguously that osteocalcin can cross the blood-brain barrier; binds to neurons in the brainstem, midbrain, and hippocampus (which is responsible for learning and memory); promotes the birth of neurons; and increases the synthesis of several neurotransmitters, including serotonin, dopamine, and catecholamine. They also found that osteocalcin-null mice had abnormally small hippocampi, a part of the brain involved in memory.
The researchers then hypothesized that the changes in neurotransmitter synthesis should alter the animals’ behavior. In a series of behavioral tests, they confirmed that osteocalcin-null mice exhibit increased anxiety and depression-like behaviors, as well as impaired learning and memory, compared with normal mice.
These changes are similar to those seen in the aging population. “As we age, bone mass decreases, and the production of osteocalcin probably does, too,” said Dr. Karsenty. “We’re currently looking into this. It is not inconceivable that treatments that boost osteocalcin levels or stimulate osteocalcin receptors could help counter the cognitive effects of aging and aging-related diseases such as Alzheimer’s.”
When adult osteocalcin-null mice were infused with osteocalcin, their anxiety and depression did decrease, “but the infusions didn’t affect learning and memory or the size of the hippocampus,” said Dr. Karsenty. “This was perplexing, so we did another experiment—a postnatal knockout of osteocalcin (a genetically engineered model in which the synthesis of osteocalcin is blocked after birth). These mice were anxious and depressed but had normal memory and hippocampus structure. The unavoidable conclusion of the two experiments was that osteocalcin must act during development.” This led to the second part of their study.
In subsequent experiments, the researchers showed that osteocalcin crosses the placenta from mother to fetus and that this maternal pool of osteocalcin is necessary for formation of the hippocampus and the establishment of memory. Lastly, they showed that once-a-day injections of osteocalcin in osteocalcin-null mothers during pregnancy could prevent the development of behavioral abnormalities in their offspring.
“This finding could explain some of the effects observed in children born from undernourished mothers who develop, with an unusually high frequency, metabolic and psychiatric disorders just as osteocalcin-null mice do,” said Dr. Karsenty. “Malnutrition decreases the activity of bone cells; as a result, undernourished mothers have low bone mass, which affects osteocalcin production. This has clinical relevance even today, in developing countries, where maternal malnutrition is still common.”
Any therapies related to osteocalcin are still years away, however, he added.
Certain types of video games can help to train the brain to become more agile and improve strategic thinking, according to scientists from Queen Mary University of London and University College London (UCL).
The researchers recruited 72 volunteers and measured their ‘cognitive flexibility’ described as a person’s ability to adapt and switch between tasks, and think about multiple ideas at a given time to solve problems.
Two groups of volunteers were trained to play different versions of a real-time strategy game called StarCraft, a fast-paced game where players have to construct and organise armies to battle an enemy. A third of the group played a life simulation video game called The Sims, which does not require much memory or many tactics.
All the volunteers played the video games for 40 hours over six to eight weeks, and were subjected to a variety of psychological tests before and after. All the participants happened to be female as the study was unable to recruit a sufficient number of male volunteers who played video games for less than two hours a week.
The researchers discovered that those who played StarCraft were quicker and more accurate in performing cognitive flexibility tasks, than those who played The Sims.
Dr Brian Glass from Queen Mary’s School of Biological and Chemical Sciences, said: “Previous research has demonstrated that action video games, such as Halo, can speed up decision making but the current work finds that real-time strategy games can promote our ability to think on the fly and learn from past mistakes.
“Our paper shows that cognitive flexibility, a cornerstone of human intelligence, is not a static trait but can be trained and improved using fun learning tools like gaming.”
Professor Brad Love from UCL, said: “Cognitive flexibility varies across people and at different ages. For example, a fictional character like Sherlock Holmes has the ability to simultaneously engage in multiple aspects of thought and mentally shift in response to changing goals and environmental conditions.
“Creative problem solving and ‘thinking outside the box’ require cognitive flexibility. Perhaps in contrast to the repetitive nature of work in past centuries, the modern knowledge economy places a premium on cognitive flexibility.”
Dr Glass added: “The volunteers who played the most complex version of the video game performed the best in the post-game psychological tests. We need to understand now what exactly about these games is leading to these changes, and whether these cognitive boosts are permanent or if they dwindle over time. Once we have that understanding, it could become possible to develop clinical interventions for symptoms related to attention deficit hyperactivity disorder or traumatic brain injuries, for example.”
Marine mammals can remember their friends after 20 years apart, study says.
New experiments show that bottlenose dolphins can remember whistles of other dolphins they’d lived with after 20 years of separation. Each dolphin has a unique whistle that functions like a name, allowing the marine mammals to keep close social bonds.
The new research shows that dolphins have the longest memory yet known in any species other than people. Elephants and chimpanzees are thought to have similar abilities, but they haven’t yet been tested, said study author Jason Bruck, an animal behaviorist at the University of Chicago.
Bruck came up with the idea to study animal memory when his brother’s dog, usually wary of male strangers, remembered and greeted him four years after last seeing him. “That got me thinking: How long do other animals remember each other?”
I Remember You!
Bruck studied dolphins because their social bonds are extremely important and because there are good records for captive dolphins (as opposed to wild ones).
So he collected data from 43 bottlenose dolphins at six facilities in the U.S. and Bermuda, members of a breeding consortium that has swapped dolphins for decades and kept careful records of each animal’s social partners.
He first played recordings of lots of unfamiliar whistles to the dolphins in the study until the subjects got bored and stopped inspecting the underwater speaker making the sounds.
At this point, he played the whistles of the listening dolphins’ old friends.
When the dolphins heard these familiar whistles, they would perk up and approach the speakers, often whistling their own name and listening for a response.
Overall, the dolphins responded more to animals they’d known decades ago than to random animals—suggesting they recognized their former companions, according to the study, published recently in Proceedings of the Royal Society B.
Working with animals as intelligent as dolphins was a challenge, Bruck added. The animals loved participating in the experiment so much that they’d often hover over the speaker, blocking the noise.
Others would begin “whistling directly at me as if I could understand them,” he said.
And one set of cheeky young dolphins swam up to Bruck and started whistling the names of the dominant males in their group in order of rank, perhaps suggesting the names they wanted to hear, Bruck said.
Memory Linked to Smarts?
Why dolphins—which live an average of 20 years in the wild—need long-term memory is still unknown. But it may have to do with maintaining relationships, since over time dolphin groups often break up and reorganize into new alliances.
This sort of social system is called “fission-fusion,” and it’s also seen in elephants and chimpanzees—two other highly intelligent and social beings.
Coincidence? Bruck suspects not: “It seems that maybe complex cognition comes from a place of trying to remember who your buddies are,” he said.