Zhiguo Wang - Eye-Tracking with Python and Pylink

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Python is becoming more and more popular among scientists. Its application in psychology has expanded from scripting computer-based experimental tasks to all aspects of research, including but not limited to data collection, analysis, and visualization. I had little knowledge of computer programming when I started my graduate study about 17 years ago. I experimented with different programming languages and tools but finally settled down with Python for its easy syntax, flexibility, versatility, and open community.

The content of this book is based mainly on my research experience and the courses I have taught previously. There are quite a few Python books on the market featuring programming tools designed for psychologists (e.g., PsychoPy). What sets this book apart is its focus on eye-tracking.

Eye-tracking is a widely used research technique in psychology and neuroscience labs. The eye-trackers used in the lab are typically faster, more accurate, and of course, more expensive than the ones seen in consumer goods (e.g., VR goggles) or usability labs. The eye-trackers featured in this book are the EyeLink series trackers manufactured by SR Research Ltd (Canada). The EyeLink eye-trackers are arguably the best research-grade tracker available on the market. This high-speed eye-tracker has unmatched precision and accuracy, and it has been used in well over 9000 peer-reviewed journal articles.

This book will first introduce the building blocks and syntax of Python, and then discuss libraries that we can use to program psychology experiments, that is, PsychoPy and Pygame. For eye-tracking, this book will cover the Pylink library in detail. The example scripts accompanying this book are freely available on GitHub, https://github.com/zhiguo-eyelab/Pylink_book . This book is a useful reference for eye-tracking researchers, but you can also use it in graduate or undergraduate level programming courses.

Special thanks go to Dr. Sam Hutton, Dr. Jiye Shen, Dr. Jon Peirce, and Dr. Sebastiaan Matht for their valuable feedback on an earlier version of this book.

To verify if you have Python 3 on your Mac , launch a terminal and type python3 at the command-line prompt. As shown in the shell output below, my MacBook has Python 3.6.6. If you do not have Python 3 on your Mac, please download the Mac OS X installer from https://www.python.org and install it.

If you use Ubuntu or another Debian-based Linux distribution, please run the following command in a terminal to install Python 3.6 or a later version.

Thousands of Python modules are actively developed and maintained by the community. These modules have greatly expanded the functionality of Python and allow users to access solutions others have already created for common problems. The preferred installer for Python modules is pip, which is now a module included in the official Python distribution. With pip, users can search, download, and install Python modules from either a public (e.g., Python Package Index, or PyPI) or a private online repository. On macOS and Linux systems, the pip command takes the following format. Here, the -m option requests the Python interpreter to look for the module that follows -m (i.e., pip in the command below) and execute it.