Loading/Adding/Subtracting/Intersecting Layers As Selections

To load a layer as a selection, press-and-hold the Ctrl (Mac: Command) key and click on the layer’s thumbnail in the Layers panel.

To add a layer to an already existing selection, press Ctrl Shift (Mac: Command Shift) and click on the layer’s thumbnail.

To subtract a layer from a selection, press Ctrl Alt (Mac: Command Option) and click on the layer’s thumbnail.

To intersect the selection press Ctrl Alt Shift (Mac: Command Option Shift) and click on the layer’s thumbnail.