Memory is the persistence of learning over time through the storage and retrieval of information. To understand memory, we can look at the extremes.
Memory employs three "steps": encoding, storing, and retrieving.
Several models of memory exist. For example, Atkinson and Shiffrin proposed a three-stage processing model: (1) sensory memory, (2) short term memory, (3) long-term memory. This model has been modified to consider the fact that some information can skip the first two steps and go straight to the long-term memory, and the existence of the working memory.
Encoding is getting information into the memory. Automatic processing occurs for information about space, time, frequency and well-learned information. Effortful processing occurs for information that requires attention and conscious effort to remember.
Storage is retaining the information you need to remember.
Sperling did a memory experiment where letters were flashed for 1/20th of a second. When asked to recall a row, participants rarely missed a letter, proving that all the letters were available for momentary recall. (Iconic memory. Echoic memory is it's auditory counterpart).
The working memory must fully encode info, otherwise it will quickly disappear. It can hold 7 items (give or take 2) at a time. It is better for digits than letters and sounds than images.
Chunking is one way to store information:
We are not sure where we store memories in the brain, or how it is stored. The memory trace is difficult to find, but we suspect it has something to do with the brain's synapses in neurotransmitters. For example, Kandel and Schwartz did a study where they classically conditioned sea slugs into a behavior and discovered that serotonin was released when learning occurs.
Did you know?
Prolonged stress can corrode neural connections, which can actually shrink the hippocampus, a part of the brain involved in memory.
Retrieving information can occur as recall, recognition, or relearning. Retrieval cues such as context or moods are often used to help retrieve something from the memory.
However, the ability to forget information is helpful too. Imagine being overwhelmed with every piece of information you've ever taken in!
Daniel Schacter proposed 7 sins of memory:
We may forget things because we never encoded them in the first place, or due to storage decay or retrieval failure (see glossary: Proactive interference and retroactive interference).
Elizabeth Loftus demonstrated how our memory is fallible as memories can be falsely constucted:
Memory is susceptible to many things that make it imperfect, such as source amnesia and the misinformation effect, making it hard to discern true and false memories.