PsychoPy

PsychoPy is an open-source software package written in Python for creating experiments in psychology, neuroscience, and psychophysics. It provides tools for presenting visual and auditory stimuli, recording participant responses, and collecting data with precise timing. PsychoPy runs on Windows, macOS, and Linux and can operate as a standalone application or as a Python library.

The package offers two primary interfaces: a graphical experiment builder (Builder) that enables users to design experiments with a flow-based interface without writing code, and a Python scripting interface (Coder) for full programmatic control. In addition to Python, PsychoPy can export Builder experiments to PsychoJS to run in web browsers via the Pavlovia platform, enabling online data collection.

Stimuli can include images, text, sounds, movies, and interactive components; timing accuracy relies on the library’s core clock and graphics backends such as Pyglet. It supports hardware input and output, including keyboards, mice, game controllers, and various data acquisition devices. It offers trial loops, randomization, and condition handling, as well as data output in CSV, JSON, and other compatible formats. The package also includes calibration tools for display characteristics and experiment monitoring.

Development and licensing: PsychoPy is open-source and released under a BSD-style license. It is maintained by a community of researchers and developers, with extensive documentation, tutorials, and forums supporting users. The project has an active ecosystem, including PsychoJS for browser-based experiments and comprehensive documentation at psychopy.org. It is widely used in academic labs and education for designing and running experiments that require precise timing and flexible stimuli presentation.