Eye-response lags during a continuous monitoring task.

We measured the temporal relationship between eye movements and manual responses while experts and novices watched a videotaped football match. Observers used a joystick to continuously indicate the likelihood of an imminent goal. We measured correlations between manual responses and between-subjects variability in eye position. To identify the lag magnitude, we repeated these correlations over a range of possible delays between these two measures and searched for the most negative correlation coefficient. We found lags in the order of 2 sec and an effect of expertise on lag magnitude, suggesting that expertise has its effect by directing eye movements to task-relevant areas of a scene more quickly, facilitating a longer processing duration before behavioral decisions are made. This is a powerful new method for examining the eye movement behavior of multiple observers across complex moving images.