In the following study you will be shown strokes taken from hand drawn sketches. You will be asked to make a decision about each stroke, telling us whether or not it could possibly be a polyline, polygon, line, arc or ellipse. You should choose Yes if it is at all possible that someone drew the stroke while trying to draw that shape.
You can use the keyboard shortcuts indicated on the buttons. However, due to bugs in some browsers, for the first stroke you may have to click one of the buttons with the mouse but subsequent strokes should respond to keystrokes.