Show people a colour and map their brain activity - the level of similarity between two people's colour perceptions should be reflected by similarities in the activity.
One persons ‘blue’ activity could be different than another’s while still being the same wavelength of light and general perception.
It's a question of subjective experience - and that experience should be reflected in electrical activity.
Given the fact that the broad structure of the brain is largely shared across members of the species, similar stimulation should trigger similar activity in the same regions of the brain.
If the same colour triggers markedly different activities, it would not be unreasonable to conclude that the subjective experiences are not the same.
Honestly, it would be shocking if it were even a little true beyond ‘frontal cortex’ levels of granularity. And even then, Phineas Gage type situations make it clear that may not actually be required either.
And that means completely different individual activity can trigger similar subjective experiences as much as similar activity can trigger different subjective experiences, no?
If I were to imagine a warrior, and his general perception of the colour red, I may find the way his brain processes the colour more closely to a rival warrior than his wife the gardener.
A real world example; London taxi drivers and bus drivers show distinct patterns of changes to the hippocampus.
https://pubmed.ncbi.nlm.nih.gov/17024677/
The way that the mapping data is stored will be heavily bias towards being spatially reflective of the real world counterpart.
Note the bias will be towards a degree structural isomorphism, one internal 2D + 1T spatiotemporal surface map of the city might be a rotation and/or reprioritisation of another - but they will have a shared basis (convergent compute simulations of biased subsets of the same real world structures), and when navigating from point A to point B, the path and nature(though not the propagation vector) of the electrical activity of both will be reflection of the same real-world surface map.
Now I say spatiotemporal - because the driver going from A to B in the morning will develop different expectations of the levels of traffic at different parts of the journey.
Or do you think fingerprints are the most random thing in humans?
There may be general patterns from above, but the actual details vary immensely when you zoom in.
Large populations may still roughly conform to a normal curve, but the volume under the deviations is still huge. And the dispersion is immense.
Anyway, I can't be bothered with this anymore since I've completely lost the ability to assume good faith on your behalf.