| # | Measure | Operational Definition |
|---|---|---|
| 1 | Overall Attention | Average percentage viewing time to the screen across all 4 stimulus paradigms (15 one-minute blocks of stimuli) |
| 2 | Attentional Scanning | Average number of glances to processing speed stimuli across all quadrant of the screen |
| 3 | Positive Emotion | Average intensity rating for happy and surprised emotions across all social attention stimuli |
| 4 | Negative Emotion | Average intensity rating for fear, anger, disgust, and sadness emotions across all social attention stimuli |
| 5 | Social Attention |
Empirically-derived measure of attention to social versus non-social information using standardized fixation duration, fixation count, and time-to-first fixation |
| 6 | Social Preference | Average of all fixation durations to social areas-of-interest across all social attention stimuli |
| 7 | Face Preference |
Average of all fixation durations to face areas-of-interest across all social attention stimuli |
| 8 | Non-social Preference | Average of all fixation durations to non-social areas-of-interest across all social attention stimuli |
| 9 | Receptive Vocabulary | Sum of all fixation durations across vocabulary target word-picture combinations (27 total targets) |
| 10 | Speed to Faces |
Average time-to-first-fixation on the most prominent face areas-of-interest across all social attention stimuli |
| 11 | Speed to Object |
Average time-to-first-fixation on each target object area-of-interest across all processing speed stimuli |
| 12 | Reading accuracy | Sum of all fixation durations across target reading words (38 total targets) |
Note. Fixations were defined as at least 66ms of gaze point samples within a 100-pixel dispersion area. Glances were defined as an entry to an AOI with at least one fixation. To increment glance count, gaze must leave the AOI, with at least one fixation outside the AOI, and then return to the AOI with at least one fixation. With the exception of the social attention measure, which was empirically-derived, social and non-social areas-of-interest were defined a priori based on our prior investigations. Non-social areas-of-interest include non-target or distractor (extraneous) objects within social scenes. Receptive vocabulary words were chosen to range in difficulty from preschool (age 2) to adult (college) words. Word frequency was also used to select target words and distractors for the single-word reading task.