This is another convenience from a writer privileging the personal experience above external explanations and expectations.
Note the use of the word qualitatively. This word asserts the importance of quality over quantity; quality can be a personal metric.
No. 2 Theory of Colour Dreaming
Investigators and dream workers have long felt
the power of colour and of sensation qualitatively described;
for colour is a set of conditions, a position,
an experience.
