Seeing our errors keeps us on our toes
June 4, 2013 — If people are unable to perceive their own errors as they complete a routine, simple task, their skill will decline over time, Johns Hopkins researchers have found -- but not for the reasons scientists assumed. The researchers report that the human brain does not passively forget our good techniques, but chooses to put aside what it has learned.
The term "motor memories" may conjure images of childhood road trips, but in fact it refers to the reason why we're able to smoothly perform everyday physical tasks. The amount of force needed to lift an empty glass versus a full one, to shut a car door or pick up a box, even to move a limb accurately from one place to another -- all of these are motor memories.
In a report published May 1 in the The Journal of Neuroscience, the Johns Hopkins researchers describe their latest efforts to study how motor memories are formed and lost by focusing on one well-known experimental phenomenon: When people learn to do a task well, but are asked to keep doing it while receiving deliberately misleading feedback indicating that their performance is perfect every time, their actual performance will gradually get worse.
It had been assumed that the decline was due to the decay of memories in the absence of reinforcement, says Reza Shadmehr, Ph.D., a professor in the Department of Biomedical Engineering at the Johns Hopkins University School of Medicine.
But when Shadmehr and graduate student Pavan Vaswani asked volunteers to learn a simple task with a few twists designed to deliberately manipulate the brain's motor control system, they learned otherwise.
The volunteers were told to push a joystick quickly toward a red dot on a computer screen. But the volunteers' hands were placed under the screen, where they couldn't see them, and their starting point was shown on the screen as a blue dot. In addition, as the volunteers moved the joystick toward the red dot, a force within the contraption would suddenly push the joystick to the left. So the volunteers practiced until they could move the blue dot straight to and past the red dot by compensating for the leftward push with pressure toward the right.
Once the volunteers had mastered the task, Shadmehr and Vaswani changed it up without their knowing. For one group of 24 volunteers, they added a stiff spring to the joystick device that would guide the user straight to the target, but would also measure the amount of rightward force the volunteers were applying. To the volunteers, it looked as though they were now doing the task perfectly every time, and, as in previous experiments, they gradually stopped pushing to the right, apparently "forgetting" what they had learned.
For a different group of 19 volunteers, though, the researchers not only added the spring, but also changed the feedback on the screen not to reflect what was actually happening during each task, but to show feedback similar to reruns of earlier efforts. The volunteers weren't seeing the errors they were actually making, but feedback that looked convincingly like errors they might have made. This group continued to do the task as they'd learned, applying the right amount of force to the joystick hundreds of times.
This shows that decline in technique "isn't just a process of forgetting," says Vaswani. "Your brain notices that you are doing this task perfectly, and you see what you can do differently."
Adds Shadmehr, "Our results correct a component of knowledge we thought we understood. Neuroscientists thought decay was intrinsic to motor memories, but in fact it's not decay -- it's selection."
The study was funded by the National Institute of Neurological Disorders and Stroke (grant number NS078311) and the Human Frontier Science Program.
Welcome to SUV System Ltd!
SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.
We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.
SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com
Electronic Components distributor:http://www.suvsystem.com
Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html
IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html
LED Distributor:http://www.suvsystem.com/l/LED-1.html
Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html
Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html
Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html
Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html
SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc
we are focus on the following fields,and hope we can help you.
CR0805-FX-1242ELF CR0805-FX-1242E CR0805-FX-1241ELF CR0805-FX-1241E CR0805-FX-1240ELF CR0805-FX-1240E CR0805-FX-1214ELF CR0805-FX-1213ELF CR0805-FX-1213E CR0805-FX-1212ELF CR0805-FX-1212E CR0805-FX-1211ELF CR0805-FX-1211E CR0805-FX-1210ELF CR0805-FX-1210E CR0805-FX-1204ELF CR0805-FX-1203ELF CR0805-FX-1203E CR0805-FX-1202ELF CR0805-FX-1202E CR0805-FX-1201GLF CR0805-FX-1201G CR0805-FX-1201ELF CR0805-FX-1201E CR0805-FX-14R3E CR0805-FX-14R0ELF CR0805-FX-14R0E CR0805-FX-1473ELF CR0805-FX-1473E CR0805-FX-1472ELF CR0805-FX-1472E CR0805-FX-1471ELF CR0805-FX-1471E CR0805-FX-1470ELF CR0805-FX-1470E CR0805-FX-1433ELF CR0805-FX-1433E CR0805-FX-1432ELF CR0805-FX-1432E CR0805-FX-1431ELF
http://www.suvsystem.com/a/2421.aspx
