Presentation software version 14

The task is illustrated in Figure 1. Two simultaneous sequences of black capital letters of the Latin alphabet were rapidly (9/s) presented left and right from fixation. The 17’’ screen had a white background (120 cd/m²) and was driven with 100 Hz at about 1.2 m from participants’ faces. Letters were 8.5 mm wide and 11 mm high (0.5° × 0.6° visual angle) with their inner edges 10 mm from fixation (0.6°). Fixation was marked by a small red cross (0.1° × 0.1°) at screen center. In each trial, two targets had to be identified. The first target (T1) was a red letter (24 cd/m²; D, F, G, J, K, or L). The second target (T2) was a blue digit (18 cd/m²; 1, 2, 3, 4, 5, 6, 7, 8, or 9). Background stimuli consisted of all other letters in black (standard), or in blue (color lures) or of the digits 1–9 in black (digit lures). Presentation^® software, version 14.5, was used for experimental control (Neurobehavioral Systems Inc., Berkeley, CA, USA).

The SRTT used in the study was a modification of the standard version introduced by Nissen & Bullemer^{62 (link)} and Willingham and coworkers^{63 (link)}. The task was programmed by means of the Presentation Software version 14.5 (Neurobehavioral Systems, Inc., Albany, USA) and stimuli were presented on a 17″ computer monitor. Participants were instructed to maintain their gaze during the whole experiment to the middle of the monitor. Detailed description of experimental parameters is presented in Supplementary Methods. To control for eyes fixation to screen centre, an eye-tracker was used (Eye-Tracker 600 Series, Eyegaze Edge, LC Technologies, Inc., Fairfax, USA). If fixation deviated from the screen centre by more than 2.6 cm at trial onset (visual angle larger than 1.3°), a large red exclamation mark appeared for 2 s in the middle of the screen attracting gaze back to the centre. Then the trial was restarted.

Participants completed a two-day paradigm consisting of habituation and acquisition training on Day 1 and extinction training, reinstatement administration and reinstatement test on Day 2. In the current study, only data from acquisition and extinction training are presented. For both acquisition and extinction training, CS+ and CS− were each presented 14 times in pseudo-randomized order for a duration of 6–8 s (mean duration: 7 s). Inter-trial intervals (ITIs) consisted of a white fixation cross presented for 10–16 s (mean duration: 13 s). Presentation of all stimuli on a grey background and stimulus timing were controlled by Presentation software (Version 14.8, Neurobehavioral Systems, Inc, Albany California, USA).