 |
|
Using brain scans, researchers find evidence for a two-stage model of human perceptual learning
March 15, 2007Washington, D.C. - Using advanced brain imaging techniques, researchers at Georgetown University Medical Center have watched how humans use both lower and higher brain processes to learn novel tasks, an advance they say may help speed up the teaching of new skills as well as offer strategies to retrain people with perceptual deficits due to autism.
In the March 15 issue of Neuron, the research team provides the first human evidence for a two-stage model of how a person learns to place objects into categories - discerning, for example, that a green apple, and not a green tennis ball, belongs to "food." They describe it as a complex interplay between neurons that process stimulus shape ("bottom-up") and more sophisticated brain areas that discriminate between these shapes to categorize and "label" that information ("top-down").
A human can't function without the ability to sort between objects and organize them in fluid ways, said the study's lead author, Maximilian Riesenhuber, Ph.D., the principal investigator for the Laboratory for Computational Cognitive Neuroscience. "We make sense of the world by learning to recognize objects as members of categories such as 'food,' 'friend,' or 'foe,' but it has not been clear how the human brain does this," he said.
The researchers theorized that a very simple yet efficient way of doing this kind of learning would be for the brain to first learn how objects vary in shape, and then, in a second stage, to learn which shapes go with which labels, allowing the brain to sort an object into different labeled "bins" when necessary. For example, a green apple and a green tennis ball are both green and round, but only an apple can be eaten and only a green tennis ball belongs to a sport.
In this study, the research team asked human volunteers to undertake a series of tasks presented to them on a computer screen. All of them involved cars that were generated with a computer graphics morphing system, allowing the researchers to generate thousands of cars with subtle shape differences. "In the beginning, all the cars looked very similar to the participants because they did not have any experience with them," said Riesenhuber. "It's like if a person had never seen faces before, they would all look similar at first."
In the first experiment, the participants looked at series of cars presented at different parts of the screen and performed simple position judgments on the images, while their brain activity was being measured using an advanced functional Magnetic Resonance Imaging (fMRI) technique that made it possible to more directly probe neuronal tuning than in previous studies. Investigators found that cars activated a particular region in participants' brains, the lateral occipital cortex, which had also been found by other studies to be important for object recognition.
Then the volunteers were given several hours of training using images of the cars. In these sessions, participants had to learn how to group the cars into two distinct categories. This was easy at first, Riesenhuber said, because the cars were obviously not alike, but then the researchers began to "tighten the screws" by making the two categories increasingly more similar.
"Over the course of the training, the participants got better at finer and finer category discriminations," Riesenhuber said. "This represents a crucial step in category learning where small differences in shape can have a big impact on category labels - as in the tennis ball and apple example - and where big differences in shape - such as between an apple and a banana - can have no impact on the label, such as when categorizing both as 'fruit'."
Now that the volunteers had learned how to categorize small shape changes, they were shown the cars from the first experiment while again being scanned, allowing the researchers to compare how training had enhanced the brain's ability to process car shapes. They found again that cars selectively activated an area in lateral occipital cortex, but that now neurons in that area appeared to be finely tuned to small car shape differences.
In a third scan, the investigators finally asked subjects to categorize the same car images shown in the other scans. This time, two areas of the brain, the now familiar area in lateral occipital cortex as well as an area in lateral prefrontal cortex, were found to be active when processing the images. "The lateral prefrontal cortex is known to be the center of cognitive control," Riesenhuber said. "That is where the brain connects physical input to an action or response, deciding what task to do and how to respond to a stimulus."
In essence, fMRI was showing that both the higher and lower brain regions had worked together to learn a task, he said.
These findings might be helpful in understanding disorders that involve differences in the interaction of bottom-up and top-down information in the brain, such as autism or schizophrenia, Riesenhuber said. It also suggests how the learning of visual skills can be enhanced by directly monitoring neuronal activity. "This could be useful, for instance, to speed up learning to detect targets in unfamiliar imaging modalities, such as baggage X rays or radar images," he said.
Georgetown University Medical Center
The researchers theorized that a very simple yet efficient way of doing this kind of learning would be for the brain to first learn how objects vary in shape, and then, in a second stage, to learn which shapes go with which labels, allowing the brain to sort an object into different labeled "bins" when necessary. For example, a green apple and a green tennis ball are both green and round, but only an apple can be eaten and only a green tennis ball belongs to a sport.
In this study, the research team asked human volunteers to undertake a series of tasks presented to them on a computer screen. All of them involved cars that were generated with a computer graphics morphing system, allowing the researchers to generate thousands of cars with subtle shape differences. "In the beginning, all the cars looked very similar to the participants because they did not have any experience with them," said Riesenhuber. "It's like if a person had never seen faces before, they would all look similar at first."
In the first experiment, the participants looked at series of cars presented at different parts of the screen and performed simple position judgments on the images, while their brain activity was being measured using an advanced functional Magnetic Resonance Imaging (fMRI) technique that made it possible to more directly probe neuronal tuning than in previous studies. Investigators found that cars activated a particular region in participants' brains, the lateral occipital cortex, which had also been found by other studies to be important for object recognition.
Then the volunteers were given several hours of training using images of the cars. In these sessions, participants had to learn how to group the cars into two distinct categories. This was easy at first, Riesenhuber said, because the cars were obviously not alike, but then the researchers began to "tighten the screws" by making the two categories increasingly more similar.
"Over the course of the training, the participants got better at finer and finer category discriminations," Riesenhuber said. "This represents a crucial step in category learning where small differences in shape can have a big impact on category labels - as in the tennis ball and apple example - and where big differences in shape - such as between an apple and a banana - can have no impact on the label, such as when categorizing both as 'fruit'."
Now that the volunteers had learned how to categorize small shape changes, they were shown the cars from the first experiment while again being scanned, allowing the researchers to compare how training had enhanced the brain's ability to process car shapes. They found again that cars selectively activated an area in lateral occipital cortex, but that now neurons in that area appeared to be finely tuned to small car shape differences.
In a third scan, the investigators finally asked subjects to categorize the same car images shown in the other scans. This time, two areas of the brain, the now familiar area in lateral occipital cortex as well as an area in lateral prefrontal cortex, were found to be active when processing the images. "The lateral prefrontal cortex is known to be the center of cognitive control," Riesenhuber said. "That is where the brain connects physical input to an action or response, deciding what task to do and how to respond to a stimulus."
In essence, fMRI was showing that both the higher and lower brain regions had worked together to learn a task, he said.
These findings might be helpful in understanding disorders that involve differences in the interaction of bottom-up and top-down information in the brain, such as autism or schizophrenia, Riesenhuber said. It also suggests how the learning of visual skills can be enhanced by directly monitoring neuronal activity. "This could be useful, for instance, to speed up learning to detect targets in unfamiliar imaging modalities, such as baggage X rays or radar images," he said.
Georgetown University Medical Center
Perceptual learning relies on local motion signals to learn global motion
Researchers have long known of the brain's ability to learn based on visual motion input, and a recent study has uncovered more insight into where the learning occurs.
'Uniquely human' component of language found in gregarious birds
Although linguists have argued that certain patterns of language organization are the exclusive province of humans - perhaps the only uniquely human component of language.
Requirement for high-level mental processing in subliminal learning
Subliminal learning is a low-level perceptual learning process that can occur without awareness of what is learned, and it is thought to occur in manner similar to that of learning based on stimuli of which we are aware.
More Perceptual Learning Current Events and Perceptual Learning News Articles
 |
Perceptual Learning (Bradford Books) by Manfred Fahle (Editor), Tomaso Poggio (Editor) Perceptual learning is the specific and relatively permanent modification of perception and behavior following sensory experience. It encompasses parts of the learning process that are independent from conscious forms of learning and involve structural and/or functional changes in primary sensory cortices. A familiar example is the treatment for a "lazy" or crossed eye. Covering the good eye causes gradual improvement in the weaker eye’s cortical representations. If the good eye is patched too long, however, it learns to see less acutely. This book presents advances made in the last decade in this rapidly growing field. The first part examines neuronal changes caused by lesions or external influences. It discusses the effects of these changes on behavior and the extent to which... |
 |
An Ecological Approach to Perceptual Learning and Development by Eleanor J. Gibson (Author), Anne D. Pick (Author) The essential nature of learning is primarily thought of as a verbal process or function, but this notion conveys that pre-linguistic infants do not learn. Far from being "blank slates" that passively absorb environmental stimuli, infants are active learners who perceptually engage their environments and extract information from them before language is available. The ecological approach to perceiving-defined as "a theory about perceiving by active creatures who look and listen and move around"-was spearheaded by Eleanor and James Gibson in the 1950s and culminated in James Gibson's last book in 1979. Until now, no comprehensive theoretical statement of ecological development has been published since Eleanor Gibson's Principles of Perceptual Learning and Development (1969). In An... |
 |
LEAP FROG PHONICS RADIO that Inspire Language Development, Exploration and Creativity, Cognitive Development, Perceptual and Motor skills by LEAPFROG TOY SPECIALTY |
 |
Wide-Mouthed Bullfrog Set singer Music with Mar (Performer) Children will clamor to read the story and join in the fun activities of this engaging CD with a pop-up book. Songs included on the CD are: Wide-mouthed Bullfrog; Apples & Bananas; Reggae Riding Hood; Dark, Dark; Spider on the Floor; The Little Old Lady Who Wasn't Afraid of Anything; I Have a Cat; Chicken Little; Three Pigs Rap; Today is Monday; Slow & Steady; All Around the Circle; Little Red Hen; B - A Bay; Come On and Sing!; The Boy Who Cried "Wolf!"; and Read to Me. |
 |
An Odyssey in Learning and Perception (Learning, Development, and Conceptual Change) by Eleanor J. Gibson (Author) In the field of psychology, beginning in the 1950s, Eleanor J. Gibson nearly single-handedly developed the field of perceptual learning with a series of brilliant studies that culminated in the seminal work, Perceptual Learning and Development. An Odyssey in Learning and Perception brings together Gibson's scientific papers, including difficult-to- find or previously unpublished work, along with classic studies in perception and action. Gibson introduces each paper to show why the research was undertaken and concludes each section with comments linking the findings to later developments. A personal essay touches on the questions and concerns that guided her research. |
 |
Thinking-Moving-Learning Also With: Jack Capon (Host) Thinking-Moving-Learning DVD by Jack Capon. Filmed in the United States at an elementary school class featuring Jack Capon showing you how to help children master a series of increasingly difficult tasks by using balance beams, ropes, balls, innertubes, etc., in a Basic Movement Education Program. This basic program became the basis for his Perceptual-Motor Lesson Plans, Level-1 and Level-2 programs for Pre-K and the Early Elementary School Grades. This is the fun way to develop body image, judging body position in space and making perceptual discriminations! 18 minutes long in DVD-R format. |
 |
Poly Balance Beam -- 8 Feet Long x 4" Wide by Poly Enterprises Ideal for the beginning gymnast, builds self confidence, balance and foot placement. Also Great for Movement Education Programs in general and more specifically Perceptual-Motor, Psycho-Motor and Sensori-Motor. This flexible, molded durable vinyl beam is 8 feet long, 4 inches wide and 1.5 inches thick (or 1.5 inches high from the floor). For ease of handling and storage, the beam can be folded to 4 feet long and can be used that way to make the walking surface 3 inches off the floor. Shipping case converts to a handy carrying case for teachers or students on the move. |
 |
Water Learning Basic Activity Set (Sharks, Frogs, Right Feet, Left Feet & Poly Spots) by Poly Enterprises This set, which includes the classic Poly Sharks and Poly Frogs, will enhance any obstacle-based water activities and inspire teachers to create endless games for their students. As in the illustration, this set includes different types of lay-flat durable 1/4 inch vinyl poly shapes which are: 6 Green Fogs; 6 Blue Sharks; Twelve 9" diameter Rainbow Poly Spots; 6 Large Right Red Foot shapes; and 6 Large Left Blue Foot shapes. |
 |
Physical Activities for Improving Children's Learning and Behavior by Billye Ann Cheatum (Author), Allison Hammond (Author) Fewer things cause more concern for parents and teachers than a child who appears to have a learning problem or behavior disorder. It is even more difficult when no specific cause or reason for the problem is given. Now, with the help of Physical Activities for Improving Children’s Learning and Behavior, you can learn about the possible underlying causes for a child’s difficulty and select from 99 fun-filled activities proven to promote sensory motor development. Authors Cheatum and Hammond, who have a combined experience of more than 40 years in the special physical education field, explain the complexities of sensory motor development in easily understood language. More than 130 photos and illustrations show the developmental processes and activities, helping you understand... |
 |
Art: Another Language for Learning by Ruth Straus Gainer (Author), Elaine Pear Cohen (Author) This book presents true stories about childhood development, with accompanying discussions about the role of the art processes as well as products. |
| © 2009 BrightSurf.com |