Figure 1.

Computer-based escape–avoidance task: one enemy spaceship appears randomly in one of six locations on the screen, approximately every 1 s. The participant’s goal is to gain points by shooting and destroying this spaceship (1 point for each hit). (A,B) The experimental groups differ in the appearance of the ITI. (A) In the first group (without-SS), background was the same as the one during the other task periods, (B) whereas in the second group (with-SS), two lights were visualized at both upper corners of the screen. (C) The warning period includes two colored rectangles at the top of the screen, which appear every 20 s and remain visible for 5 s. (D) On acquisition trials, the warning period is always followed by appearance of a bomb, which remains on-screen for 5 s (bomb period). The bomb period is divided into five segments of equal duration; during each segment, there is an explosion and loss of 5 points to a maximum of 25 points. (E) At the bottom corners of the screen, there are two box-shaped areas representing “safe areas.” Moving the participant’s spaceship to one of those boxes is defined as “hiding.” While hiding, the participant’s spaceship can not be destroyed and no points can be lost, but neither can the participant shoot the enemy spaceship and gain points. Labels shown in white text are for illustration only and do not appear on the screen during the task.