in Photoshop CS4, how do I make an adjustment layer apply only to the layer directly beneath it?

Question

I know I can do this:

• select adjustment layer
• ctrl-click layer beneath it
• invert selection and delete

But this only captures the CURRENT shape of the lower layer. So if I later edit it, the mask won't be updated and I'll have to re-capture it. So what's the right way?

Answer 1

in the adjustment tab, third icon in the footer row from the left, the one that looks like a slide switch.