Eye-Gaze Cueing Task
The task was computer displayed and controlled, using in-house software,
and was delivered on a PC. Participants were seated 60 cm directly in
front of a computer monitor, in a dimly lit, sound-attenuated room and
their heads were held steady with a chin/head rest. A trial sequence of
the procedure is shown in Fig. 1. Each trial began with a fixation
stimulus consisting of a schematic face (3 X 2.5 degree of visual angle)
with the pupils centred vertically in the eyes. After 700 ms, the cue
was presented. The cue was the same central schematic face with the
pupils directed either to the left or to the right. It was not
predictive of the target location. Finally, the target (the letter “O”
or the letter “X”) appeared to either the left or right of the screen.
Cue and target remained on the screen until a response was given or
until 1,500 ms had elapsed. The participants pressed the “C” key for
one target and the “M” key for the other target. The assignment of
targets to response keys was counterbalanced across participants within
each group. Cue-target SOA, measured from the appearance of the cue to
the appearance of the target, was fixed at 300 ms. The participants were
encouraged to respond as quickly and accurately as possible. They were
also informed that the location signaled by the cue did not predict
target location and that they should ignore it while maintaining central
fixation throughout each trial. The experimental session was composed of
15 practice trials followed by 68 experimental trials. Four catch
trials, in which no target was presented, occurred randomly in each
block. Cued location and target location were randomly selected.