What do psychologists call the ability to quickly revise and remember things that a person had previously learnt
Looks like when your friend was freshly learning the equations, he was using more of his episodic memory but as he went &quot;used-to&quot; with the equations, he tapped into more of semantic memory.
Lets use familiar example. When we recite something, we usually apply the episodic memory. It works much like how we searched a song &quot;along&quot; a tape of a cassette recorder. We had to forward/ rewind repeatedly to find the song.
We use semantic memory when we use language (or anything we learn at a depth and develop some experiene in it). Such as while reading, we instantly recognise the letter L (a shape) is linked with sound ELL or the word &quot;CAT&quot; indicates a mental image of a furry carnivorous animal. We do not scroll through the entire alphabet. If we compare episodic memory as a cassette system, then semantic memory is more like a modern digital file folder system, which is just &quot;browse, click and play&quot; type.