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PsyScript: an introduction

What it is

PsyScript is what used to be called an 'experiment generator'. It's designed to allow someone experimenting on adults or children to expose a participant to various stimuli, allow them to respond, and note how they responded and how long they took to respond.

PsyScript can show images and text, and play sounds and movies. It can take a collection of stimuli and 'shuffle' them differently for each participant so they're presented in a random order, to negate order effects. It can note reactions by the participants pressing keys or clicking on things shown on the display. It can look how the participant reacted and do different things depending on what they did (e.g. depending on whether they got something right or wrong). It can repeat operations a fixed number of times, until something happens, or until a fixed amount of time has passed.

A PsyScript session (one participant doing one experiment) results in a log, a multi-line tab-delimited set of numbers and strings suitable for pasting into SPSS or Excel or feeding to any analysis program which can read text. The log is completely free-format: you can write your script to log what you want in the order you want it, logging responses and reaction-times, fixed text, and meta-information like date-stamp and time-stamp.

Supported platforms

PsyScript does everything inside a web browser, but allows you to do three things:

Because different web browsers on different equipment do things differently, they don't all allow all these things to happen.

ChromeFireFoxSafariInternet ExplorerMicrosoft EdgeTablets and Smartphones
Develop and edit
Run an experiment on your computer
Run an experiment on a server

The weird situation with Microsoft Edge is because it doesn't support a JavaScript feeature called "localStorage" for local files. Consequently it cannot store log results. I do not know why this decision was made or whether Microsoft intends to change it.

What it's suitable for

PsyScript was originally designed to teach university-level students how to conduct psychology experiments. However, it was picked up and used to conduct real psychology experiments, and some forms of medical testing. It has been used at teaching and research establishments in Europe, America and Asia for experiments on adults and children, healthy and unwell, unmedicated and medicated. Results gathered using PsyScript have been used for undergraduate degrees, postgraduate degrees, professional research, the teaching of psychology and medicine, pump-priming, and clinical assessment.

The current version of PsyScript was written with serious research (rather than teaching and demonstrations) in mind, and changes were made to the underlying design and the scripting language which improve its use for serious research, at the expense of making it a little more complicated to use.

What it's not suitable for

PsyScript 3 is not designed for testing which involves measuring reaction times with an accuracy or precision on the order of 1 millisecond. It runs in a web browser, and web browsers aren't designed for precision timing. If you need perfect timing of how long a stimulus is shown, you need a tachistoscope. If you need perfect measurement of how long a participant takes to react, you need a video camera that shoots hundreds of frames a second. However, for experiments like these you can still use PsyScript to display the stimuli and react to the participant's actions, you will just need to capture the reaction times externally to PsyScript, possibly using a high-frame-rate video camera.

PsyScript 3 is not designed for 100% accurate reproduction of colours in images, for timing of movie frames, or for perfect reproduction of pitch or timing in sounds. This is not caused by any fault of PsyScript, it's because the sort of multi-purpose computer you'll be running it on can't do any of those things. Computer monitors don't reproduce colour from image files correctly. Operating systems don't allow precise timing of movie playback. The sound circuitry in a modern computer doesn't allow perfect reproduction of a sound stored in a sound file. If you need any of those things, use an appropriate device, not a multi-purpose computer.

PsyScript 3 is not warranted to be of sufficient quality for use in testing for legal or medical certification processes. If you need medical-certification quality testing, pay a medical-certification testing company to do it or pay a programmer to develop exactly the program you need.