Generally, an experiment will consist of stimulus displays based on which a participant makes a response. For example, you may present strings of text, geometric shapes or bitmap images. This is where the sketchpad item comes in.
The sketchpad provides simple built-in drawing tools, which allow you to very easily draw stimulus displays.
The sketchpad also has an option Start response interval. If you select this option, OpenSesame will start timing from moment the sketchpad is presented. This is convenient if you want to record response time from the presentation of a particular sketchpad.
The Duration entry can be set to any positive numeric value which reflects the duration of the sketchpad in ms. If you want no duration, for example because the next is a keyboard_response, you can enter '0'. You can also enter 'keypress' or 'mouseclick' to show the sketchpad until a key is pressed or a mouse button is clicked, respectively.
You can use the 'Show if' input field in the sketchpad to specify conditions under which items should be shown/ hidden. For example, if you want to have the direction of an arrow depend on the 'cue' variable, you could draw two arrows and use '[cue] = left' and '[cue] = right' conditions to determine which arrow should be shown on a given trial.
For performance considerations, a sketchpad is prepared before the execution of the sequence that it is part of. Therefore, conditional statements cannot depend on what happens during the sequence (after the sketchpad has been prepared). This is not the case for feedback items, which are prepared 'at runtime' and can therefore be used to provide immediate feedback to participants.
Examples of valid conditional statements are (note that no quotes are required and that variable names should be placed between square brackets):
always
never
[variable_name] = value
[variable_name] != value or [another_variable_name] = another_value
2 > 1 and 1 < 2
For more information about conditional statements, see <http://osdoc.cogsci.nl/usage/variables-and-conditional-qifq-statements>.