"Trinsic" of Intrinsic and extrinsic
In order to remember intrinsic feedback and extrinsic feedback, it's important to remember the suffix "trinsic". Although this isn't the whole word, remembering an association between feedback and "trinsic" will enable you to recall intrinsic and extrinsic.
The following mnemonic will help you remember "trinsic" and feedback:
I feed and rub the dogs back (feedback) but what the dog really loves when she has performed particularly well is to get a trinket as a basic (trinsic) prize.
Hear feedback think of "trinsic" i.e. Intrinsic and extrinsic.