I really struggle with memorising piano music. I can memorise flute/ single-line music but, despite trying lots of strategies for memorising piano pieces, the most I can usually manage is a couple of bars. There are only 2 notable exceptions:- The Maple Leaf rag and a grade 6 piece from a few years back (Vals poetico- Granados).
Over the last couple of weeks some of my piano students have been working on 1 of the AB grade pieces and although I have demonstrated an occasional bar to them I haven't played it completely through more than a handful of times. However in the lessons we have studied the patterns, harmonies and fingerings. Yesterday, while idly filling in the few minutes between pupils, I amazed myself by playing it from memory not just once but several times and on further experimenting found I could pick up & play from any point. Which might not sound much to people who can easily memorise but was quite an achievement for me especially as I hadn't played it over & over again but had simply spent a lot of lesson-time looking at & thinking about it.

That's one of the main things I do when I memorise something - pick it to bits

Thanks for sharing this - I shall mention it to my OH who can sightread pretty much anything but struggles with memorising.

Interestingly - his new teacher told him to spend time on the analysis before playing a new piece, so maybe it's a tried and tested technique. Thanks for sharing, Andy.

Whilst sitting in daughter's piano lessons I hear the teacher always mention about grouping / Chunking / patterns.

I have found the same thing. I find it hard to memorise on any instrument but just sitting beside my daughter while she practises has meant that I can play a lot of her piano pieces from memory.

Unfortunately, now that she is older she no longer wants me sitting with her while she is practising so I'm not sure if the above technique works much above Grade 2 standard pieces.

It's funny you should have come up with this topic today as yesterday I was reflecting on this very subject and found a fairly interesting web page which theorises about how anxiety gets in the way of memorising music.

I find it very difficult to memorise anything and the more I worry about it, the less likely it is to happen.

I did find myself really surprised once in the middle of a warm-up on the oboe, when I found myself playing a Schumann Romance that I'd never studied with my teacher and had probably only played through myself two or three times. I'd listened to it a lot though. I'd got through a good three lines of it (as written on the page) before I realised what was going on. As soon as I became conscious of it and tried to remember some more, I couldn't.

I would agree that it is probably because you weren't actively trying to memorise that it happened. The real difficulty is how to translate this into action to improve memorisation. There can't be any other skill where one would be told NOT to work at it in order to improve!

I sometimes think the brain just loves to play these sort of tricks on us!

I think this is why I find baroque/classical music much easier to memorise than modern stuff. You can find all the patterns and work out all the harmony in a relatively sensible fashion. Once you know where something's headed it's much easier to work out what has to go in the middle. Learning standard chord progressions and doing advanced theory has helped me immensely with both piano sight reading and memorising.

It's similar to how pop music lyrics are easier to learn than normal prose because of the rhyming words... and the "grouping" that sunil mentioned is probably similar to how everyone knows the order of the colours on joseph's technicolour dreamcoat but if they were just given another list of 29 colours to remember in order would find it very difficult.

Here's that web page I mentioned, on Anxiety and Memory: Their Effects on Cognition and Musical Performance. Bit of a heavy-sounding title on a website entitled "Neuroscience for Kids" but actually short and readable.

I'm currently learning the Mozart C minor fantasia and two movement's from Turina's Circus Suite for Piano.
The Turina is full of complex chords and accidentals but this is what I have memorised. I didn't think that I'd be able to but I also think that with all the keyboard acrobatics it's not a piece I'd like to have to rely on reading.

Parts of the Mozart I have memorised but there's a lot of it that I haven't.