That’s what it struck me as being. I’m not certain if it’s cultural or innate, but in Western culture we describe higher frequency pitches as high and lower frequency pitches as low - hence the arrows and the differing vertical positioning. Obviously different shapes indicate significant differences in the sequences, and horizontal location indicates timing of various segments.
I don’t see music as shapes at all, but I can certainly pick up a obvious and simplistic symbolic representation on the fly. It says pretty much nothing about the way I perceive music, except in a cultural sense: high frequency = higher pitch, further to the right means later. I suspect a person coming from a language written right to left or vertically would do poorly on this test. I don’t know if all cultures consider higher frequency pitches to be ‘higher’ or not, but if there are those who do not, they would have flunked this test immediately.
In short, I think this has nothing to do with synesthesia or pre-synesthesia, and everything to do with cultural assumptions (and recognizing that a different shape or color correlates with a different melody and or arrangement).