Cycling Through Layerblend Modes – Part 1
Sometimes it's useful to quickly cycle through your blend modes to see which one works best. Manually clicking on each one just isn't quick, so try this: Click on the Blend Mode list in the top left of the Layers panel to select a blend mode. Then press Shift – + to cycle down the list and Shift – – to go back up.
There is an other way, U can press the blend mode list and make it aktive, then U can cycle up and down by pressing the up-arrow key and the down-arrow key. I don´t know if this works on a MAC
A even faster way is to just click in the blend mode list and then use the up and down arrow keys on your keyboard. 🙂