The Echoes of the Mind (62) Duration


From a temporal perspective memory bifurcates into short-term and long-term. What is simply called memory refers to long-term memory: the selective accumulation of life experiences, both from environmental ecology (perception) and cognitive processes (imagination, reason, and intuition). The capacity of human long-term memory is practically unlimited, though the sometime struggle with recall belies that impression. Memories unrecalled fade over time.

Short-term memory differs from long-term in duration and capacity. Short-term memory is of the current situation or task at hand. The instant of attention is working memory.

Rehearsal is process of retaining information in short-term memory by repeating it. Repetition is simply reentry into the evaporating depository which lasts less than a minute. Rehearsal is commonly employed in remembering phone numbers to input.

The best way to learn motor skills is repetition on multiple maneuvers. The skills take longer to learn, but the moves are more securely embedded in long-term memory, as short-term memory proves inadequate, due to contextual interference: the emptying of short-term memory to handle a new situation.

Continually wiping out motor short-term memory helps update long-term memory. ~ French cognitive scientist Nicolas Schweighofer

Repeating a single task does not necessarily engender long-term memory, as short-term memory may cover a single skill.

Working Memory

Working memory is the portion of short-term memory that is the focus of immediate attention. It is brief – a fraction of a second – and its capacity paltry.

One bit of information is the amount of information that we need to make a decision between two equally likely alternatives. ~ George Miller

The most influential psychology article of all time – written in 1956 by American cognitive psychologist George Miller – claimed that working memory can cope with ~7 bits (7±2) of information before confusion sets in. Miller was wrong. 4 bits is the limit of working memory. A 7-digit number is remembered by being parceled into smaller chunks, with no more than 3 numbers per mnemonic lump.

To remember a seven numeral phone number, say 6458937, we need to break it into 4 chunks: 64. 58. 93. 7. Basically, 4 is the limit to our perception. ~ Australian psychiatrist Gordon Parker


The idea of dividing memory duration into short-term and long-term dates at least to William James in 1890. The foregoing explanation follows the now-conventional modal model proposed by American psychologist Richard Atkinson and American cognitive scientist Richard Shiffrin in 1968.

Because the mind stitches memory together into a seamless experience, and teasing them apart experimentally has been somewhat inconclusive, the bifurcation between short-term and long-term memory remains controversial. The organization and mechanics of memory retain mystery.