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

4.5 Description of available Components
This section describes the types of stimulus and response components which are available to you in v 1.0 alpha.
It is important to understand what these are and what properties can be defined for them before you design an
experiment.
The components are listed by name; this name is used in the XML to signify which type of component you want.
Currently there are only visual components — all visual components take properties including width, height,
and background and foreground colours. Additionally you can specify font properties for textual components.
4.5.1 Text
The text stimulus allows you to present some text on the slide. You can provide no text and thus use this
stimulus as a coloured box. You can specify line returns within your text by typing \n.
4.5.2 Image
The image stimulus allows you to display a jpeg, png or gif image on the slide. You can stretch the image by
specifying a size. Animated gifs should work, but cannot be resized.
4.5.3 Button
The button stimulus provides a clickable button. This can be used simply to advance the slide, but also to
provide a set of options. All buttons when clicked will advance the slide, but the button name is recorded and
so this stimulus can be used as a response.
4.5.4 Input
The input component is a response component, and allows you to get textual input from the subject. You can
specify which characters are allowed and the maximum length of the input.
4.6 Responses and reusing values
You can use the responses you collect to affect later slides. Any value which is saved to the results can be
retrieved and used. Currently the value can only be used as a property value in a new component, but in future
could be used to decide conditional paths through an experiment.
Note: This feature is not fully functional if you use templates to describe your experiment. See section 5.5.4.
4.7 Randomisation of an experiment
It is possible to specify parameters which affect the ordering of slides within a stage. Note that this is only
possible within a stage; the stages themselves remain in the order in which they are described in the XML, and
there is no way to randomise across stages. There are two ways to reorder the sequence of an experiment.
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