Figure 1. Schematic of the backward masking majority function task (MFT-M).

(a) The sequence of a trial in the MFT-M (2:1 condition). Stimuli events are indicated by color-coding. Participants were required to report the majority of arrow directions (left or right). (b) Possible congruency ratios (majority : minority) of arrow sets. Set size represents the total number of arrows. (c) Timeline of the stimuli under different stimulus exposure time (ET, in seconds). Duration of each event is illustrated by the length of each color bar. A response was required within a 2.5 s response window and the total length of each trial was 5.75 s. (d) The block structure and order. There were 12 task blocks in this task (lower panel), corresponding to 12 possible combinations of set size (represented by the color of a block) and ET (represented by the height of a block). Each task block consisted of 36 trials, with equal proportion of all possible congruencies under the corresponding set size (represented by color patterns in upper panel). The order of blocks was randomized between participants.