An illustration of the sequence of events for each problem: The problem began with a 3-second fixation and then was followed by a problem that stayed on the screen until the participant answered or until 30 seconds were up.

<p>Participants responded by entering the answer in a numerical keypad. This was followed by feedback on the correct answer and its expansion. After seeing the feedback for 5 seconds, there was another 3 seconds of fixation. After this, participants were given a repetition-detection task for 12 seconds. In this task letters appeared on the screen at the rate of 1 per 1.25 seconds. Participants were instructed to click a key each time they detected a pair of letters that were the same. Also illustrated are the four regressors used for analysis – a 3 second “Fixation” regressor corresponding to the initial fixation period, a “Pre” regressor for the period from problem presentation to response initiation, a “Response” regressor for the period of response generation, and a ‘Post” regressor for the 8 seconds until the start of the repetition detection.