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January 2011



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 The Brain by Inner Rebel

By Rick Nauert PhD Senior News Editor
Reviewed by John M. Grohol, Psy.D. on June 1, 2010

A new research study investigates how the brain updates our memory bank so as to improve our expectations of future rewards.

The refresh is necessary so that we may make accurate predictions about those rewards in the face of a changing environment.

Although exactly how the brain orchestrates this process remains unclear, the new study suggests that a combination of two distinct learning strategies guides our behavior.

A paper about the work will appear in the journal Neuron.

One accepted learning strategy, called model-free learning, relies on trial-and-error comparisons between the reward we expect in a given situation and the reward we actually get.

The result of this comparison is the generation of a “reward prediction error,” which corresponds to that difference.

For example, a reward prediction error might correspond to the difference between the projected monetary return on a financial investment and our real earnings.

In the second mechanism, called model-based learning, the brain generates a cognitive map of the environment that describes the relationship between different situations.

“Model-based learning is associated with the generation of a ’state prediction error,’ which represents the brain’s level of surprise in a new situation given its current estimate of the environment,” says Jan Gläscher, a postdoctoral scholar at Caltech and the lead author of the study.

“Think about a situation in which you always take the same route when driving home after work, but on a particular day the usual way is blocked due to construction work,” Gläscher says.

“A model-free learning system would be helplessly lost; it is only concerned with taking actions that in the past were rewarding, so if those actions are no longer available it wouldn’t be able to decide where to go next.

“But a model-based system would be able to query its cognitive map and figure out an efficient detour using an alternative route.”

Read in Full:  http://psychcentral.com/news/2010/06/01/brain-images-reveal-how-learning-strategies-work/14175.html

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