Eye-tracking IQ: Cognitive capacity and strategy use on a ratio-bias task.

This study tested the relationship between strategy use (assessed by eye-gaze patterns), cognitive ability (CA), and reasoning performance on a ratio-bias task. For the ratio-bias problems, participants (N = 125) chose which of two ratios was larger; each ratio was represented both as a fraction and as a picture. Problems were solved in two blocks: once under a deadline (Time1) and once in free time (Time2). Consistent with the assumption of dual process theories that CA is needed to overturn a pre-potent, initial response (Evans & Stanovich, 2013), CA was positively associated with correct performance at Time2, as well as the increase in performance from Time1 to Time2. However, strategy use predicted performance independently of CA at Time2, and accounted for the relationship between CA and improvement between Time1 and Time2: reasoners who attended to the fractions rather than to the misleading pictures performed better, regardless of CA. CA also predicted performance at Time1. Together, these findings suggest that the robust relationship between CA and reasoning (Stanovich, 1999) may arise because 1) high capacity reasoners are more likely to "intuit" the initial answer and 2) because CA is correlated with good strategy use, which, in turn, predicts performance.