First of all, that lightness and
darkness values are really the most fundamental aspect of vision.
Lightness and darkness in relation to luminance values in the real world,
that's absolutely necessary for having vision in the first place.
Without it, we're blind.
Second point I made was that we don't see qualities in the same way physical
instruments measure them.
In this module,
we've been talking about the instrument that's basically a photometer,
the instrument that's not very complicated that's in your smartphones that measures
the physical light intensity, adjusts it, as I said, for human sensitivity.
And the third point is that tracking the experience aligns lightness percepts
on a subjective scale, that's what we've just been talking about,
according to their impact on success in the world,
which ultimately depends on feedback from reproductive success.
I mean, of course, we think of these things in our own human lives as
being very remote from reproductive success, but they're not.
Over the course of human history, this is what it's been about and still is about.
The fourth point is that this strategy is a way of getting around
the inverse problem, and as I've said several times already,
this is the main problem that vision has evolved a strategy to contend with.