A child I know (7 years) is very early in learning (swarajathi) and "knows about" a handful of ragas, and that too learnt with just some (and not all) the gamakas. I tried testing the child's skilll the other day - the test being of course skewed against the testee by my ability to sing something in tune

).
I told that the answer would be one of the following: mohanam, bilahari, khamas, nATTai (the child knows the gItam), cencuruTTi (child knows a song), malahari, kAmbhOji, SankarAbharaNam.
Just my emphasizing the "ri" of nATTai as I sang mahAgaNapatim - sometimes repeating that part so that the child pays extra attention on it - the child got the right answer. This was also true for another song in nATTai as well. The child obviously doesnt know enough to recognize all the contours of the raga, but that characteristic ri - was enough.
Also I sang sujanajiVana, and just that "ma~~~~" - was enough for the right answer khamas (based on the opening line of swarajathi).
This tells me that we "weight" certain characteristics of raga high and use it to zero in quickly.
of course if someone sang vAgadIswari - the answer would have been "nATTai" as well. Same for say nATakurinji with the ma being stopped as ma~~~~, for a khamas answer.
But then I sang the opening line of dorakuNa, and the child answered bilahari. There the answer involved more complexities. Somehow teh child was able to detect the underlying similarity of the first line's melodic to something from the bilahari swarajathi.
Of course it wasnt success all times. e.g. I sang sRI cakra rAja - opening para, and the child did not see it as cencuruTTi then (but has in atleast one other case).
Also kAmbhOji, SankarAbharaNam etc. were much harder as actual songs are more complex than the respective gItams. The child could not correlate (as I expected).
Arun