Learn how memories are made. Find out how we know about memory and learning.
How are Memories Made?
Declarative Versus Procedural Memory
Declarative memory is the type of memory that most people think of when discussing memory. Declarative memories are memories of facts and events that people can consciously recall, while procedural memory refers to unconscious memory abilities, such as skill learning or habit learning.
Declarative memory refers to factual memories and autobiographical events that people can consciously recall. Four major steps of in memory formation include working memory, short-term memory, consolidation, and long-term memory. Each is distinct and depends on a different region of the brain to function. An example of declarative memory is the recollection of facts you learned in school such as the world’s capital cities.
Working memory allows people to hold limited amounts of information in the mind, which can then be manipulated to support other tasks like learning, reasoning, or acting. Information held in working memory typically lasts a short duration (a few seconds). An example is remembering that you are phoning the complaints department while you are waiting on hold.
- Prefrontal Cortex
Short-term memory holds information that needs to be remembered, but not manipulated. People can typically hold around seven items in short-term memory, but that number can be improved through “chunking”. Chunking allows more information to be remembered by sorting objects into meaningful groups. An example is looking up a phone number then remembering it long enough to dial it.
- Temporal lobe
Memory consolidation is important to both declarative and procedural long-term memory. Sleep provides an off-line period that is favorable to memory consolidation.
- Temporal lobe
Long-Term Declarative Memory
The conscious memories that may be recalled years after learned or experienced. Long-term memories are stored in the cortex. The temporal lobe is no longer needed. An examples include the multiplication tables you learned in school or the name of your childhood pet.
Long-Term Procedural Memory
Procedural memory refers to the collection of skills, habits, and dispositions that are inaccessible to conscious recollection. Examples of procedural memory formation have been demonstrated through skilled motor learning. Examples include riding a bike or driving a car.
- Basal Ganglia
Heightened emotions can enhance both declarative and procedural memory, though the exact mechanism is unknown. This works through “conditioning,” which is a process that can encourage or discourage events or behavior through either reward or punishment.
How Do We Know About Learning and Memories?
Learn about the studies that have led to our knowledge of learning and memories.
Experiments That Have Shaped Our Understanding of Learning & Memory
Experiments with humans and animals have helped scientists understand how the brain learns and forms memories. Press the next button to learn how we know about working memory, long-term memory, procedural memory, and more.
Working Memory, Monkeys, & Delayed Response
A delayed response task was administered to trained monkeys by placing a piece of food in one of two boxes in a table. The monkey’s view of the objects was then blocked and the boxes were covered. After a delay, normal monkeys could remember the location of the food. Monkeys that had damage to the prefrontal cortex could not remember and would reach randomly for the food.
Memory & Patient H.M.
Scientists have learned a lot about memory from patients with amnesia. In the 1950s, doctors performed an operation on Patient H.M.’s temporal lobe and removed two-thirds of his hippocampus to relieve epilepsy. It cured his epilepsy but also cause him to lose his memory of most events in the years before the surgery, and to be unable to form new long-term memories. Older memories remained intact, and he had relatively intact short-term and procedural memory. This suggests the hippocampus is involved in long-term, declarative memory in particular.
Studies indicate that over time, long-term memories are stabilized through a process called consolidation. Following consolidation the hippocampus is no longer necessary for the storage of these memories. This is why H.M. retained many of the memories formed prior to the removal of his hippocampus, because many of these older memories had already been consolidated. Another line of evidence is studies that looked a recall of Spanish up to 50 years after it was first learned in school. The results showed that some information was stable over a long period of time.
Processing During Sleep
Sleep may play an important role in memory consolidation. Scientists recorded the neural activity of rats being run through a maze. During sleep, the neural firings in the hippocampus and coordinated activity in the cortex repeated a similar pattern as was seen then the rats were in the maze. This suggests that sleep may be important for consolidating memories in the cortex.
Priming & Procedural Memory
Priming studies show how people are better able to process information that they have recently encountered. For example, subjects shown a series of objects will name an object faster if they seen it a short time earlier even if they don’t recall seeing the object. For amnesics like H.M., without memory of a previous encounter, the priming effect remained intact, indicating that priming is a form of non-declarative memory.
Conditioning & Memory
Conditioning is the learned association between a particular environmental stimulus and a behavioral response. Ivan Pavlov first detailed classical conditioning in his famous experiments with dogs. In those studies, Pavlov found that dogs could be trained to associate a previously neutral stimulus (a bell) with food. Eventually, the bell alone triggered salivation in the dogs, even when food was withheld.