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Example of stimuli used in the four-dot backward masking task. A fixation cross was shown for 450 ms followed by a 500 ms blank screen. Potential targets, consisting of squares with notches cut in the top, left side, or bottom, were then shown for 25 ms. A mask, consisting of four-dots that surrounded one of the potential targets, was presented for 37.5 ms. The mask served as the cue to the participant as to which target they were to identify the direction of the notch.
