Learning Classified: The Physical Manifestation of Explicit and Implicit Learning

By Nishi Jain ’21

The prefrontal cortex, the brain’s center for implicit and explicit learning, forms the basis for the interactions that constitute for our learning through positive and negative feedback loops.(Source: Wikimedia Commons)

Learning is something of a bilateral endeavor: it is composed explicit and implicit learning and memory.

Explicit learning is the learning that you are consciously aware of—when you can articulate what you are learning because you have been actively been thinking about it. For example, you are engaging explicit learning when you are actively trying to learn something for a class or actively memorizing a poem.

Implicit learning could be considered as the opposite—it is related to muscle memory and it is the learning that you are not consciously aware of. You are engaging in implicit learning when you are trying to learn how to ride a bike, or learning to perfect your performance in a sport.

Recently, researchers have been able to produce physical evidence for each type of learning based on the neural signatures that that they have produced on brain-wave scans. Based on this, Professor Earl K. Miller, the Picower Professor of Neuroscience at the Picower Institute for Learning and Memory and the Department of Brain and Cognitive Sciences, stated that this discovery could put science leaps and bounds ahead in the study of the neurobiology that was associated with motor learning through complex tasks.

This would take place through analysis on the aforementioned brain scans. When neurons fire and signal in the brain, they give off an electrical signal that, when aggregated together, form the brain waves that are visible on brain scans. Based on the patterns of neuron signals, these brain waves oscillate at different frequencies.

Scientists then went a step further to understand the different frequencies that characterized explicit and implicit learning. During explicit learning, there is an increase of alpha2-beta waves that oscillate at 10-30 hertz after the person makes a correct choice and then also an increase in delta-theta waves (which oscillate at 3-7 hertz) after there is a wrong choice made. As learning progressed and was successful, however, there was a decrease in alpha2-beta waves, showing that as the brain became more accustomed to learning the material, the brain didn’t react as strongly to the material anymore because the learning model had already been built.

Delta-theta waves, previously associated with incorrect choices that were made in explicit learning, actually increased with correct answers in an implicit learning task. As the process further and the muscle memory was built, they gradually decreased, thus creating an inverse relationship between implicit and explicit learning in relation to delta-theta brain waves.

An interesting implication lies with Alzheimer’s patients, whose explicit learning decreases with dementia. But if others are able to revert to the other kind of learning, implicit learning, the patient may be able to rely on that form of learning in order to lessen the impacts of the disorder. Implications of this research are far and wide, and scientists are searching for greater and farther application of this researching—comparing the brain’s explicit and implicit learning in an effort to greater understand how we complete tasks, and our thinking behind it.

Source: Matthew V. Chafee, David A. Crowe. Implicit and Explicit Learning Mechanisms Meet in Prefrontal Cortex. Neuron, Volume 96, Issue 2, 11 October 2017.