Long term memory refers to the immense body of knowledge and skills that we hold in a more-or-less permanently accessible form.

Our name, date of birth, the letters of the alphabet, how to read, how to write, how to drive, swim, play chess, catch a ball and everything else that we "know" is all held in our long term memory awaiting activation.

Activation will occur as a direct result of our working memory querying long term memory for specific factual information (through our consciousness). Once a query has been made activation (and the 'answer') is effectively instantaneous.

Knowledge and skills that are activated with extremely high regularity, such as walking and talking, may be activated 'automatically' without the need for high levels of conscious attention, even though the task itself may be a complex one.

Consider each of the following questions.

Question 1: What is your name?

You will be able to answer this quickly. It is no surprise since it is referred to frequently and consists of only a few words. Note how quickly you can provide the answer.

Question 2: What are the letters of the alphabet?

Again, you will be able to answer this quickly but this is a more interesting question than the first. Here there are 26 items in the answer (for a standard English alphabet) and virtually everyone presents the 26 items in the same order. Our long term memory holds the letters of the alphabet in alphabetical sequence. If you try to say the letters of the alphabet in a random order, then you will find it an extremely difficult, probably impossible task.

Question 3: Who won the lottery in 1992 at Wattle St., Sydney, Australia?

Most people will quickly realise that they do not know the answer to this question. They recognise almost immediately that this is information that is not currently held in their long term memory. Generally, people "know that they don't know" many specific aspects of knowledge.

References

Simon, H. A., & Gilmartin, K. (1973). A simulation of memory for chess positions. Cognitive Psychology, 5, 29–46.