How to install a package that can be used by the python in PsychoPy?

I want to install a package that can be used by the python interpreter of PsychoPy. The command “pip install the_package” only installs the package for the regular python 2.7 installed under C:\Python27, so it can be imported correctly in that python interpreter. But when I run “import the_package” in the PsychoPy shell, it gives error “ImportError: No module named the_package”. So how can I install the package I need for the python of PsychoPy, for example, what is the pip command for PsychoPy? Thanks a lot!

This looks a lot like this topic: Installing Matlab Engine to Psychopy

Thank you for the reply. I later added the paths to PYTHONPATH environment variable so PsychoPy can see the package I need. Specifically, I want pydevd so that I can debug the code line by line in PyCharm, so I add:
C:\Program Files (x86)\JetBrains\PyCharm 2016.1.2\helpers;C:\Program Files (x86)\JetBrains\PyCharm 2016.1.2\debug-eggs\pycharm-debug.egg
to PYTHONPATH. Then, I’m good to enjoy the PyCharm’s IDE and debugger.

Thank you again for the help.

zzzzz in future please tick “solution” to the correct answer so we can see this topic is finished