Tasks
Discarding task . We modeled the discarding task from prior research (Baldwin, Whitford, & Grisham, 2016) in which participants were asked to imagine that pictures of newspapers displayed on the screen belonged to them. They were told: “Newspapers can contain important information, but it’s also important to declutter your home. Therefore, we want you to get rid of some of your newspapers.” Pictures of various newspapers were presented (see Figure 1), and participants were asked to select only the newspapers containing text (vs. pictures and text, the No Go distractor) to discard (the Go target) via button press.
The targets and distractors were counterbalanced across participants. Trials began with (a) a central fixation crosshair presented for 800-1000ms followed by (b) either a target or a distractor image presented for 112ms followed by (c) a 2000ms response period. Participants were instructed to respond as quickly as possible while remaining accurate in their responses. EEG was segmented to the onset of participant responses. Go and No Go trials were presented at a ratio of 75:25, respectively. After the first 20 trials of only No Go stimuli, Go and No Go pictures were presented at random in blocks of 300 trials each (75 No Go trials), lasting approximately three minutes per block. Prior research has established that the ERN can be reliably measured with only 14 trials and similar published tasks (Baldwin, Whitford, & Grisham, 2016) reported error rates > 70%.
It should be noted that we modified the visual appearance of the newspapers from the Baldwin, Whitford and Grisham (2016) task in order to make the task more challenging. In the original Baldwin study, red (Go target) and blue (No Go distractor) newspapers were used. In our study, we used only blue newspapers, some of which had text only (Go target) vs. pictures and text (No Go distractor).