Interestingly the electrodes were implanted in the "tactile information" processor, so the infrared light is interpreted as touch. That would seem to mean that in "tracking" the source of the signal, the rats meander until the infrared light hits their eyes, and then head toward it as the strength of the touch signal increases.

TFA says "a new sensory input can be interpreted by a region of the brain that normally does something else," but isn't the input just being "converted" into the sense of touch by activating that region of the brain?

So you increase the surcharge with some high school math.

If the cost is x and the surcharge is y, then we need:
(x + y) * .03 = y.
.97y = .03x
y = x * .03/.97

So the surcharge you should charge in this case would be y = 3.0928 (or in general, 3.0928% for a 3% credit card transaction fee).

The question is about change in wages, not absolute wages. If IT wages started higher but have remained flat, why is that?

Of course this is practically useful. Even if you have to run it multiple times before arriving at the right answer, you're virtually guaranteed to get there in orders of magnitude less time. Just verify the result (multiply the factors, try to decrypt whatever you're guessing the key for, etc.) until it's correct.