Sense data versus physical reality

I recently saw a picture, posted at This is an image of a cartoon girl, whose eyes have irises of the same colour, physically, but which, when we look at them, appear to be distinct. One eye looks teal, the other looks yellow, but both are in fact grey.

So here we have light of the same frequency, yet when humans look at it, we see different colours – because the surrounding colours are different.

The point that I want to emphasize, however, is that the sense data, or sensation, which we experience, is distinct, despite the fact that the physical light which hits our eyes is the same! Sensations can differ even when the physical reality is the same, due to surrounding circumstances. And yet, those sensations are objectively different – the sense data which we have in our minds is distinct.

My wife says I’m an idiot for not realizing this is the case, because this is rather ubiquitous. Perhaps the most common area where this appears is that two people can touch the same object, and one can feel it as hot, one feel it as cold, depending upon the states of the parts of their bodies with which they touch the object. Which is a very good point, and I credit her for coming to this realization so much more easily than I did. For me, it took this picture to make me observe this.

In any case, I primarily want to point out that yes, we experience the same colour differently, but not because of subjectivity, but because the sense data is objectively different. I have observed what happens to this colour as we move it from one region of the picture to another, and the sense data objectively changes. Our eye, or our mind, or whatever one wishes to call it, produces a different sensation depending upon where this colour is located.


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