Figure 1.

Experimental design. (A) Spatial arrangement. Five white luminous dots (angular size 0.2°) were presented on a black computer screen at 57 cm from the subject (required convergence 6°), one at the center of the screen; the others at an eccentricity of ±10° horizontally or vertically. (B,C) Temporal arrangement. Each trial started by lighting one central dot during approximately 1500–2000 ms. For the gap task, between the fixation offset and the target onset, there was a gap of 200 ms (B); for the overlap task, the fixation stays on 200 ms after the target onset (C). The target, one of the eccentric dots, appears for 1500 ms.