This task was coded by Swann Pichon and Naima Gradi and adapted from the affective backward task implemented by Suzanne Schweizer and colleagues (2019). Please refer to this paper if you use this code: https://wellcomeopenresearch.org/articles/4-91 This task implements two sessions of the backward digit task with negative and neutral IAPS images. Numbers are presented at a rate of one per second. The first digit cannot be 0 Following digits can be 0 but cannot be the same as the previous digit. If the answer is correct the span is increased for the next trial If the answer is wrong the span is decreased for the next trial. If there are at least two errors at a given span and that represents more than half of the total attempts at that span then the experiment ends, returning a span of one less than the final span attempted. Some of this initial code has been forked from VESPR / Digit Span that we deeply thank for his/her contribution