The color of the shape.
<clearscreen> <shape>
Can be set to any named color (e.g., brown, green, blue, lightyellow, ...).
The following trial sets the color of a shape based on whether or not the response to the previous trial was correct:
<trial feedback>
/ontrialbegin = [ if (trial.test.correct == true) shape.feedback.color = green; else shape.feedback.color = red; ]
/ stimulusframes = [1=feedback]
</trial>