Trial Variables

‍With trial variables, you can vary aspects of trial presentations. There are four types of trial variables:

• Position: present visual stimulus at random locations on the screen, e.g. for visual search
• Color: present shapes or text in different colors, e.g. for Stroop experiments
• Rotation: present text, pictures, or shapes at different angles
• Time limit: vary the exposure time of a slide or how much time a participant has to respond

‍A trial variable consists of trial levels.

‍Creating Trial Variables

‍Complete editing of trial variables can be done when you click on Trial Variables in the sidebar. More conveniently, you can create them on the fly in the Trial Designer. Here is how it is done for colors:

‍In the screenshot above, a text object is selected. To make its color variable, click on the Color edit button then click on the button. SuperLab will prompt you to choose from some preset colors:

‍If you need different colors than the preset ones, you can define those colors later on by clicking on Trial Variables in the sidebar. For now, click on the Next button; SuperLab will ask you to name this new trial variable. Click on OK when done.

‍Back in the Trial Designer, click on the blue checkmark; SuperLab will show swatches of the colors used in the variable:

‍The same approach can be used to create other types of trial variables in the Trial Designer:

• For position and rotation, click on the Arrange tab in the inspector and then click on the edit button next to Position and Rotation.
• For time limit, click on the Slide tab, then on the edit button next to “Advance to Next Slide”, then click on the After a time limit… checkbox.

‍Randomizing Trial Levels

‍Click on Trial Variables in the sidebar. Editing trial levels is self-explanatory. Click on the Level Selection tab for more interesting options:

‍By default, trial levels are randomized with no replacement. You can change that, as well as set other options.