If you need an inexpensive and relatively fast USB-based digital interface for your laptop you might be interested in the FTDI UM245R device (cost under $30 USD) and the Python support class that I developed for use in my Research Instrumentation course.
The device has 8 digital lines that can be configured for any combination of inputs and/or outputs. It uses TTL logic level (logic high = 5 volts) and is capable of input/output latencies of less than 1 millisecond. If more I/O lines are needed multiple devices can be used.
Complete details and software downloads can be found on the following web page:
Utility for Fast FTDI USB I/O in Python
The module is compatible with PsychoPy and requires just a few lines in a Custom Code tab to deploy via Builder.
Enjoy.
Frank Schieber
University of South Dakota