Psychometric speed was measured by the digit symbol substitution test, a performance subtest of the Wechsler Adult Intelligence Scale – Revised (Wechsler, 1981) which requires the participant to pair random digits with their matching symbols. Inspection time and choice RT were the elementary cognitive tasks administered. Inspection time was measured using a backward masked, line discrimination task. A parameter estimation by sequential testing procedure was employed (Findlay, 1978; Pentland, 1980) to vary stimulus duration. To minimise bias from random responses and lapses in attention/interest factors, inspection time was estimated by fitting post hoc a cumulative normal curve (mean = 0) to accuracy as a function of stimulus onset asynchrony. See Luciano et al. (2001b) for more details. Mean RT of correct responses on a visual reaction time task with three choice conditions (two, four, and eight) was performed on a computer using a keyboard response pad. The number of trials presented in each of the two, four, and eight choice conditions was 96, 48, and 96, respectively. RT trials less than 150 ms or greater than 2000 ms were excluded
