# Studying the Role of Visuospatial Attention in the Multi-Attribute Task Battery II
## 2 Materials and Methods
### Procedure and Task  
The experiment consisted of three blocks. The first and third block of the experiment were experimental measurements of capture of visuospatial attention in visual search tasks in which participants had to search for a color-defined target and report the orientation of a cross inside the target (upright or oblique). A singleton distractor was sometimes presented together with the target and away from the target. The singleton distractor could be of a relatively target-similar color or of a relatively dissimilar color, and it was expected to interfere with target search. These blocks consisted of three rounds of 84 trials each. The visual-search task was split into two blocks, one before and one after the second block, so that we could calculate a test-retest reliability of the measures of visuospatial attention. The second block, in-between the visual-search blocks, was the Multi-Attribute Task Battery (MATB-II). Before the experiment started and after each block, the eye-tracker was calibrated for each participant. To ensure proper calibration throughout the experiment, a fixation check was executed at the start of each trial in Blocks 1 and 3. Figure 2 shows an example of a trial used in the visual search task, adapted from [PERSON] and [PERSON] (2018) [9]. Before the first block started, participants were shown the target color (below in coordinates of the L*a*b* system; L*: luminance; a*: red/green value; b*: blue/yellow value), which was fixed throughout the experiment and either Red 1 (L*a*b* = 62.7/79.0/65.7), Green 1 (L*a*b* = 62.5/ -69.4/52.5), Red 2 (L*a*b* = 62.0/76.7/21.1), or Green 2 (L*a*b* = 62.3/ -15.8/52.7), with color balanced across participants. Participants also received an explanation of what the trials would look like, and that their reaction time, as well as the number of correct responses mattered. Each trial started with the presentation of a black fixation cross at screen center for 500 ms. Here, we conducted a fixation check. If necessary, we conducted a drift correction of the eye tracker during the fixation check. Next, the target display was presented. It consisted of seven discs. One disk was in the participant's target color. The other six were either all color-nonsingletons in a neutral, gray color (L*a*b* = 62.0/12.7/ -35.8)--these were the distractor-absent trials--or five gray nonsingletons plus one singleton-color distractor--these were the distractor-present trials. Each participant saw two types of distractor-present trials: trials with  
Figure 2: Example of a trial in the visual search task (Blocks 1 and 3). a target-similar or (top-down) matching singleton-color distractor (e.g., if Green 1 was the target color, the target-similar distractor would have been presented in Green 2); and trials with a target-dissimilar or nonmatching singleton-color distractor (e.g., if Green 1 was the target color, the target-dissimilar distractor would have been presented in Red 1). Distractor-absent, distractor-present/target-similar, and distractor-present/target-dissimilar trials were presented separated in rounds of the first and the last block--that is, those conditions were the same for the 84 trials (e.g., 7 possible target positions \(\times\) 6 possible distractor positions \(\times\) 2) of each round (e.g., 84 distractor-absent trials before 84 distractor-present/target-similar trials). By blocking distractor conditions, we decreased the likelihood of shifts between different top-down search settings even further. This was done to ensure that visuospatial attention rather than task shifting explained visual-search task performance. However, by these runs of different conditions in the visual-search task blocks, we might have also inadvertently encouraged suppression of attention capture, especially by the more target-dissimilar, nonmatching distractor: it is known that repeating distractor colors might help establish proactive suppression of the misleading distractor [30; 31; 32].