Assessment of visual orienting behaviour in young children using remote eye tracking: methodology and reliability.

Human orienting behaviour requires a complex interaction between the visual and the oculomotor system. We present orienting gaze data measured in children using a remote eye tracking system. The aim of the study was to validate a data analysis method which did not require off-line correction of data gaps due to eye blinking or inadequate gaze tracking. In two sessions, blocks of short movies, amongst others cartoons, were shown to 35 children (2-9 years) for a test-retest analysis. The cartoons were subsequently shown in one of the monitor corners. Orienting eye movements were analysed on the basis of saccadic reaction time (SRT), reaction time to fixation (RTF) of cartoon and gaze fixation area (GFA) Differences were tested for significance using the Wilcoxon-signed ranks test and reliability was assessed using the intraclass correlation coefficient (ICC). SRT values could be calculated in approximately 50% of gaze data and ranged between 150(30)ms (mean(SD)) and 390(190)ms (average SRT(min) and SRT(max) values of all subjects). RTF values could be derived in approximately 90% of gaze data with an average RTF(min) of 210(30)ms and RTF(max) of 570(160)ms. Test-retest analysis showed a significant increase of GFA during the second session with approximately 5% (P<0.05). The reliability of RTF(min) and GFA was best with an ICC of 0.84 and 0.80, respectively (P<0.0001). We conclude that remote eye tracking is well suited for quantification of timing and executing oculomotor fixations during orienting behaviour tasks. The presented method may be applied in young children with developmental disorders or brain damage.