Recreational & Family - trigger shifters

For the right side (as one is seated) for the typical 8-shift, the upper trigger raises the shift # and the lower trigger lowers it (lower number, easier to pedal, more revolutions to get the same distance, better for upgrades). On the left side (typically the 3-shift), which way does the upper trigger change things?

On my bike, there really isn't an "upper" and a "lower"...one is operated by the forefinger, and one is operated by the thumb. I think of them as the trigger and the hammer of a pistol. I presume that by "upper" you mean the finger-operated one, so I'll use "upper" for that one, and "lower" for the thumb-operated one..

The two shifters will work in the opposite direction (at least all the ones I've seen do), in one sense. The left hand upper trigger will decrease the number (easier to pedal) and the lower trigger will increase the number (go faster and farther).

In another sense, the left and right work in the same direction. The upper moves the chain to the smaller sprockets in both cases.

Thanks deraltekluge - that was pretty clear.

You'll see the same sort of thing with twist-grip shifters. Twisting the right-hand grip so that the upper side moves away from you will increase the number (move the chain to a smaller sprocket). Twisting the left-hand grip so that the upper side moves away from you will decrease the number (move the chain to a smaller sprocket).