Apparent text size affected by color? Name for that effect?

Factual Questions
1

There are street light decorative banners in our downtown that display identical text, but some banners are black text/yellow background, and others are yellow text/black background.

Although I’m sure the actual font size of both is the same, visually the black text on yellow background looks smaller. Significantly so, even. Enough to make me do a double take when I first saw them. Bright margins around dark letters look larger than dark margins around bright letters.

Is there a term for this effect?

2

I don’t have a definitive answer, but it’s possible there is not a formal name.

Here’s a summary of a study that tries to explain Galileo’s comment that Venus appears larger to the naked eye than Jupiter. The story is from 2014 and says the matter had not been previously explained.

The Wikipedia list of optical illusions does not seem to have a name for the effect of light objects seeming larger.

3

Is this just because we don’t really see black? When you see something yellow, it’s because yellow light (or a mixture of non-yellow wavelengths that average to yellow) is entering your eye and stimulating it; when you ‘see’ something that’s black, it’s because no light (or comparatively little light) is entering your eye from that direction.

For the same reason, a light source can blur and appear bigger than its actual angular size, and light hitting your retina can spill over (halation) to adjacent receptors in a way that darkness can’t - because ‘dark’ isn’t a thing - it’s the absence of a thing (that thing being light).

It’s a bit like why noise is louder than silence.

4

Mostly we don’t see areas but edges. This has been pretty solidly understood for ages right down to how neurones are wired.
So it is likely that the edge detection is slightly skewed by colour contrast. We don’t see in RGB either, but more akin to Lab, which is luminance plus two orthogonal coordinates in a colour space. The processing for that lives behind the retina, and happens before the signal leaves the eye.
What is known is that cool colours seem to recede relative to warm ones, and dark colours advance relative to light ones. This may well be tied up in the mix of colour encoding and the edge detection system, where the edge seems to move depth either side of it depending upon the colours. It may be a simple artefact of the way the edges are processed.
So the name of the effect may well be colour recession or at least something similar.

5

I don’t know the name for it, but as a graphic designer, this is something we have to make modifications for (eg logo on black rather than white), so it’s a well known visual effect.

6

Yeah, what our minds see is a mix of signals from rods and cones. And we have many more rods than cones so that mix must heavily depend on luminance for resolution.

7

If I had to make a guess, I would say it is due to chromatic aberration along the border of the background and the text.