How do I revert to a previous package in Anaconda?

If I do

    conda info pandas

I can see all of the packages available.

I updated my pandas to the latest this morning, but I need to revert to a prior version now. I tried

    conda update pandas 0.13.1

but that didn't work. How do I specify which version to use?

I had to use the install function instead:

    conda install pandas=0.13.1