Study intervention
depression, ABM
BLIND
Participants were randomized to receive either ABM or a sham condition. ABM was a computerized visual dot-probe procedure adopted from Browning et al. (Stimuli consisted of pairs of images of faces displaying emotional expressions: positive (happy), negative (fear or anger) and neutral. Each stimuli pair was derived from two out of three valences (positive-negative, negative-neutral, positive-neutral) displayed horizontally in random order, for either 500 or 1000 ms. Immediately after, a probe (one or two dots) appeared on the computer screen in one of the two locations of the previously displayed stimuli. Participants were instructed to as fast and accurately as possible to indicate the correct number of dots in the probe. Each session consisted of 96 trials with equal number of the three stimuli pairs.In the ABM condition, the probe appeared in the location of the screen where the relatively more positive stimuli had been displayed for 87% of the trials, and in the location of the relatively more negative stimuli for 13% of the trials. By being exposed to this condition, participants should implicitly learn to deploy their attention to the location of the relatively more positive stimuli, thereby developing a less negative AB. In the sham condition, there was no contingency between probe location and stimuli (i.e. the probe appeared in the location of the screen where the relatively more positive stimuli had been displayed for 50% of the trials). In all other respects, the sham condition was equal to the active condition.Participants were informed that the trial would investigate the relation between attentional focus and depression. They were also informed about the potential therapeutic properties of ABM and about the randomization procedure but were kept blind of their allocation. However, they were not given any details on the difference between conditions.According to the preregistration of the trial, the plan was to include an assessment only condition in addition to ABM and the sham condition. However, due to restraints on conducting research during the COVID-19 pandemic, allocation to this condition was discontinued after including five participants. This change to the protocol was registered in clinicaltrials.gov.