Types of long-term memory

Long-term memory holds very different kinds of information. Two ways of classifying it:

Declarative vs procedural memory:

• Declarative memory holds facts, names, dates and events, things that can be put into words ('Mount Everest is the highest peak in the world').
• Procedural memory holds how to do things: skills and steps, such as how to tie shoelaces, swim or make a cup of tea. It is hard to describe in words but easy to perform.

Episodic vs semantic memory (Endel Tulving), both within declarative memory:

• Episodic memory holds personal experiences, with their place, time and feelings. You may remember the day your team won the inter-school final: where you stood, the noise, how happy you were. These memories are often emotional.
• Semantic memory holds general knowledge and meanings, not tied to when or where you learnt them: that water boils at 100 °C at sea level, or what the word 'democracy' means.

Some special kinds of memory:

• Flashbulb memories are unusually vivid memories of where you were and what you were doing when you heard surprising, emotionally important news.
• Autobiographical memory is the memory of events from one's own life. We remember very little from the first 4 to 5 years of life, a pattern called childhood amnesia. Recent years and the period of youth and early adulthood are recalled most.
• Implicit memory influences us without our awareness. Expert typists type quickly but often cannot say where each letter is on the keyboard. In priming, seeing something earlier makes a related response easier later, even if we do not remember seeing it.

How LTM is measured:

• Recall: producing the information yourself, as in an essay question (free recall, serial recall, paired-associates).
• Recognition: picking out the right answer from choices, as in a multiple-choice question. It is usually easier than recall.
• Sentence verification: judging statements as true or false ('A sparrow is a bird'); the time taken shows how knowledge is organised.
• Priming: measuring how an earlier exposure speeds up or shapes a later response.