Coleridge referred to antimnemonics, which were things that made your memory worse:
the habit of perusing periodical works may be properly added to Averroes'* catalogue of Anti-mnemonics, or weakeners of the memory…..
*Ex. gr. Pedicalos e capillis excerptos in arenam jarere incontusos; eating of unripe fruit; gazing on the clouds, and (in genere) on moveable things suspended in the air; man's delirium, riding among a multitude of camels; frequent laughter; listening to a series of Jests and humorous anecdotes, as when (so to modernize the learned Saracen's meaning) therefore transfer this species of amusement, one man's droll story of an Irishman inevitably occasions another's droll story of a Scotchman, which again by the same sort of conjunction disjunctive leads to some etourderie of a Welshman, and that again to some sly hit of a Yorkshireman ; the habit of reading tomb-stones in church-yards, &c..
Reading tombstones? That’s worrying: walking in graveyards is one of Rose’s favourite hobbies. That’s one of the reasons why we liked Syracuse so much; wonderful, wonderful graveyards, one of the best we’ve seen anywhere.
Though, checking online, I see that
Coleridge actually misremembers the source. Not Averroes, a Muslim Aristotelian, but Burhan al-Din, as translated by Jean Baptiste de Boyer, Kabbalistische Briefe (8 vols)--James Engell & W. Jackson Bate
Wouldn’t want to mislead you.