WebExp2 Experimenter's Manual - School of Informatics - University ...

1 Introduction
WebExp2 is a toolbox for conducting psychological experiments over the World Wide Web. This section provides
an overview of WebExp2 and describes the main features available, along with the advantages of conducting
experiments over the web.
Note: Please refer to the glossary in section 10 for explanation of terminology used in this document. Some
terms, though familiar, will have specific imnport in the context of WebExp2.
Client-Server
one another.
WebExp2 is a client-server system, consisting of two separate programs which interact with
• the Server is an application which you run on the web server machine which hosts the experiment files.
It waits for client applets to connect to it and request experiments, whereupon it provides (serves up) the
experimental files, and manages the results that are returned.
• the Client is an applet which runs in the browser of the participant. It connects to the server to get the
experiment, administering it to the participant and returning results to the server.
Java & XML WebExp2 is written in Java, and uses XML as the description language for a) defining experiments
and b) storing results. There are two parts to the system: the server (an application), and the client (an
applet). Java is specifically designed to be platform-independent and is particularly suited to running across
the internet. So the WebExp2 server can run on Windows, Linux, Unix, MacOS, and anyone with a browser
can run the experimental client. As a data-description language, XML is standardised, flexible, and supports
simple validation of the data.
In order to get WebExp2 ready for use, you need to accomplish a handful of tasks. It is a good idea to get the
system working with one of the supplied paradigms, and then you can go on to designing your own experiments
to run on the system.
1.1 Features
Experiments are designed around a sequential stimulus/response model. This model can be seen as a ‘questionnaire’
where you provide a series of ‘questions’, each of which involves the presentation of stimuli and the
collection of responses (via the presentation of a set of response options).
1.1.1 Implemented
These features are implemented in the current release of WebExp2 and form part of the core functionality of
the system.
Paradigms There are a handful of sample paradigms implemented and included with WebExp2. These can be
easily modified to create your own experiments, or can be studied to provide tuition in how to achieve particular
effects with the system. The following paradigms are available:
• the Stroop task (parametric 2-condition)
• attractiveness and pupil size (nonparametric 2-condition)
• discriminant reaction times
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