This is a fascinating area of psychological introspection. As a layman let me outline my approach.
When I hear a 'new song' my mind races to capture a few melodic phrases to latch on and then ignoring the sahityam I mentally try to elaborate the raga by humming (of course not while at concerts
 )when suddenly the 'pattern matching' process of the brain produces some phrases or words from a known song whose raga I already know well. At this point I tentatively try to check whether the further elaborations of the music fit the guessed raga. Most of the time it works. But then the 'bank' of kritis that I have in my failing
 )when suddenly the 'pattern matching' process of the brain produces some phrases or words from a known song whose raga I already know well. At this point I tentatively try to check whether the further elaborations of the music fit the guessed raga. Most of the time it works. But then the 'bank' of kritis that I have in my failing  memory is not large and frustration sets in. Now I let my subconscious work on it and after a few hours the answer flashes in most often! My final approach is to look-up the sahityam (if I can get the initial words) in our Lakshman's magnificent song Index.
 memory is not large and frustration sets in. Now I let my subconscious work on it and after a few hours the answer flashes in most often! My final approach is to look-up the sahityam (if I can get the initial words) in our Lakshman's magnificent song Index. I would love to hear about other techniques from you!
 ;) ). Since confirmation step is skipped, this can sometimes lead us to later give sheepish smile, when we find it is not raga X.
;) ). Since confirmation step is skipped, this can sometimes lead us to later give sheepish smile, when we find it is not raga X.