VIEW YOUR LAYER MASK AS A RUBYLITH

If you want to view your layer mask by itself (rather than how the layer mask affects your overall image), hold the Option key (PC: Alt key) and click directly on the layer mask thumbnail in the Layers palette. This will display just the mask itself. You can also view the layer mask like a Rubylith (a red overlay used in traditional masking) that appears over your image by pressing the Backslash key (\) on your keyboard.

©ISTOCKPHOTO/ANA AMORIM