PsyScript: a Macintosh application for scripting experiments.

PsyScript is a scriptable application allowing users to describe experiments in Apple's compiled high-level object-oriented AppleScript language, while still supporting millisecond or better within-trial event timing (delays can be in milliseconds or refresh-based, and PsyScript can wait on external I/O, such as eye movement fixations). Because AppleScript is object oriented and system-wide, PsyScript experiments support complex branching, code reuse, and integration with other applications. Included AppleScript-based libraries support file handling and stimulus randomization and sampling, as well as more specialized tasks, such as adaptive testing. Advanced features include support for the BBox serial port button box, as well as a low-cost USB-based digital I/O card for millisecond timing, recording of any number and types of responses within a trial, novel responses, such as graphics tablet drawing, and use of the Macintosh sound facilities to provide an accurate voice key, saving voice responses to disk, scriptable image creation, support for flicker-free animation, and gaze-dependent masking. The application is open source, allowing researchers to enhance the feature set and verify internal functions. Both the application and the source are available for free download at www.maccs.mq.edu.au/-tim/psyscript/.