This article will discuss three aspects- learning, memory and retention.

Key Messages:

Learning refers to the process of acquiring new knowledge and skills.

Memory refers to the process by which the knowledge and skills are retained for the future.

Memories are formed when a group of neurons fires together when activated. They are stored in pieces and distributed throughout the cerebrum.

The previous article described the stages of memory:

Immediate memory–> Working memory–> Long-Term memory

Long-Term memory is of two types:

• Declarative (conscious/ explicit memory)
• Nondeclarative (implicit memory)

Nondeclarative memory includes

• Procedural memory (How to do something)
• Motor skill memory
• Emotional memory

Declarative memory includes

• Episodic memory (memory of autobiographical events)
• Semantic memory (knowledge of data and facts that may be unrelated to any event)

Learning is the process by which the interplay of the brain, environment, and nervous system acquires information and skills.

Retention requires conscious attention by the learner, and building of conceptual frameworks that have sense and meaning for long-term storage.

 What affects Retention of Learning?

• Rehearsal (the reprocessing of learning)
• Primacy-Recency Effect
• Duration of the learning episode
• Teaching method

1. Rehearsal

The long-term retention of cognitive concepts is not possible without rehearsal.

Retention depends upon

• the time allotted to rehearsal
• the type of rehearsal carried out

Time for rehearsal

When information first enters working memory, it is Initial rehearsal. If sense or meaning is not attached, and there is no time for processing, the information will probably be lost.

Secondary rehearsal occurs when enough time is allowed to review the information, make sense of it, extract the details, and assign relevance as well as value.

Closure: secondary rehearsal performed at the end of a learning episode

Type of Rehearsal

Rote Rehearsal: used when there is a need to remember and store the information precisely as entered into working memory

Elaborative Rehearsal: employed when it is important to associate new learning with past knowledge, and the information need not be stored exactly as learned.

Example: Students employ rote rehearsal to memorize a passage, but use elaborative rehearsal to interpret its meaning.

2. Primacy-Recency Effect

This refers to a common phenomenon wherein we tend to remember best:

• that which comes first; then
• that which comes last; and least
• that which comes just after the middle of the learning episode

Therefore, new learning should be timed accordingly.

3. Duration of the learning episode

Research shows that more retention happens when learning episodes are shorter.

Two 20-minute sessions will be more effective than a single 40-minute episode.

Learning episodes less than 20 minutes are ineffective.

4. Teaching Method

Learners who teach others, or use the new learning immediately, retain 90% after 24 hours.

Figure 1: Retention rate by teaching method*

This supports the adage ‘teaching is learning twice’. (It also explains why teachers retain so much of the content.)

Learning is accelerated when new content is practiced frequently in a short time span. This is called massed learning. However, if it is not rehearsed quickly, it will drop out of the system.

Figure 2: Degree of recall with distributed practice*

Sustained practice over time, called distributed practice, is the key to learning.

Caution: Whatever is learned first should be correct- relearning is very difficult and time-consuming.

Sleep and Long-term memory

The REM stage of sleep is when information is encoded to long-term memory sites. Cutting down on sleep decreases the number of REM cycles available for encoding to long-term memory.

Learners who get less sleep are more likely to get poorer grades than those who sleep longer.

Information Retrieval

There are two methods for retrieval

• Recognition (matching a stimulus with stored information)
• Recall (sending cues to long-term memory, retrieving the information, consolidating it and decoding it into working memory)

In both methods, neurons must fire along pathways to the storage sites and back to working memory. The more often this happens, the easier it is to retrieve information, and vice-versa.

The rate of retrieval depends on the nature of the learner’s storage method- a learned skill- rather than on intelligence.

The rate of learning and retrieval are independent of each other.

Chunking

When the working memory recognizes a set of data as a single item, it is termed chunking.

Example 1: The word chunking is recognized as one word, instead of 8 separate letters.

Example 2: Try remembering the following letters after looking at them for just 10 seconds:

KFCC CDB BCT VU SA

Now try the same with the letters below:

KFC CCD BBC TV USA

You may have noticed that the sequences are identical, except that the letters are grouped (chunked) differently. However, the new grouping has more meaning than the original.

Chunking is an effective way of enlarging the capacity of the working memory, and to help learners make associations that establish meaning.

Although there is a limit to the number of chunks working memory can handle, there seems to be no limit to the number of items that can be combined into a single chunk.

Forgetting

This may be due to losing the neural pathways to long-term storage sites, and happens when a memory is not retrieved for a long time.

When memories are frequently recalled, the networks strengthen with each rehearsal, and is called consolidation. This enables retrieval over decades if there is frequent recall.

Summary:

Almost no cognitive concepts can be retained without rehearsal.

Retention best occurs when 

• enough time is available for secondary rehearsal to occur
• the learning episodes are about 20-minutes long
• secondary rehearsal occurs towards the end of the learning episode
• new learning occurs at the beginning and end of a learning episode
• there is massed practice initially, followed by distributed practice later
• the learner teaches the new learning to others, or immediately puts the new learning into practice.

Perfect practice makes perfect

Adequate sleep is crucial to long-term memory.

The rate of retrieval depends upon the method of information storage- a learned skill- not intelligence.

Chunking allows learners to increase the capacity of working memory.

Forgetting is often because the neural pathways have been lost due to infrequent retrieval.

Frequent retrieval consolidates long-term memory, and allows easy recall over time.

Further Reading:

1. Sousa DA. How the Brain Learns: A Classroom Teacher’s Guide. 2nd ed. Thousand Oaks, California: Corwin Press, Inc.; 2001.

*Image from: Sousa DA. How the Brain Learns: A Classroom Teacher’s Guide. 2nd ed. Thousand Oaks, California: Corwin Press, Inc.; 2001.