Wakefield's Daily Tips

[wakecarter]

Set initial values if you update Each Frame

Online, if you an attribute of a visual stimulus is updated Each Frame then the first frame of presentation will use default values (e.g. position [0,0]) even if the stimulus starts after the routine has started. To solve this issue, set suitable default values in Begin Routine.

For example:

polygon.setSize([.2,.2])
polygon.setPos([-.75,-.5])

Often I just set the initial size to [0,0] (e.g. polygon.setSize([0,0])) so the stimulus isn’t visible until the second frame.

Animated text (i.e., position set every frame) appears at (0,0) initially

URL of experiment: (still debugging) I am doing an auditory four-interval oddball task, in which participants here four stimuli and have to response whether two or three were different from the rest. To help them, there are the numbers 1 to 4 on the screen, and an animated underscore moves below each number when each stimulus appears. That all works well, however, even though the initial position is set right at the start of the experiment, the underscore appears at position (0,0) for probably…