Photoshop increase brush size shortcut


I currently wish to use the shortcut to increase or decrease brush size in Photoshop by selecting a brush and option clicking then dragging to the left or right. This brings up a red brush preview and the hardness can be adjusted by moving up and down with the mouse.

For some reason this functionality doesnt work on my Mac running Photoshop CS6. As soon as I press option, the eyedropper tool opens instead. Any thoughts would be helpful.

Many thanks.

3/3/2016 3:21:00 PM

] - Increase Brush Size
[ - Decrease Brush Size

3/3/2016 5:58:00 PM