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Table 1 Summary of eye-tracking battery

From: Attention training for infants at familial risk of ADHD (INTERSTAARS): study protocol for a randomised controlled trial

Task

Summary

Cognitive control adapted from [24, 49]

At the beginning of each trial, the infant is presented with a fixation point in the centre of the screen. Once the infant looks to the fixation point, an audio reward is presented, followed by a visual reward (a short animated clip), which is presented on either the left or right of the screen. The visual reward is presented on 1 side for 9 consecutive trials (pre-switch) before switching to the other side for the subsequent 9 trials (post-switch). Anticipatory saccades are coded based on the child’s looking behaviour during the anticipatory window (between the start of the auditory reward and the start of the visual reward). The dependent variable is the percentage of trials in which infants make a correct anticipatory saccade towards the location of the target stimuli in the pre- and post-switch phases.

Sustained attention adapted from [24]

The infant is presented with two ‘interesting’ (complex, detailed) and two ‘boring’ (noncomplex) static stimuli. For each stimulus, the experimenter records the length of the first 5 of the infant’s looks towards the stimulus presentation area. To qualify as a look the infant must visually engage with the stimulus for at least 1 s. To terminate the look, the infant must disengage from the stimulus for at least 1 s. The longest of the first 5 looks is termed the peak look duration. The dependent variable is the peak look duration towards the interesting stimuli.

Gap-overlap adapted from [47, 50]

The infant is presented with a stimulus in the centre of the screen. Once the infant fixates on this central stimulus, a peripheral stimulus appears on the left or right of the screen. When the infant moves their gaze from the central to the peripheral stimulus they receive an audiovisual reward. There are three conditions in this task: baseline, overlap and gap. In the baseline condition, the central stimulus disappears at the same time that the peripheral stimulus appears. In the gap condition, there is a 200-ms gap between the removal of the central stimulus and the appearance of the peripheral stimulus. In the overlap condition, the central stimulus remains on the screen after the peripheral stimulus appears. The dependent variable is the saccadic reaction time (ms) to move the eyes from the central to the peripheral stimulus in the overlap condition.

Sequence learning adapted from [51]

The infant is presented with a target cartoon character (e.g. a bunny rabbit) that can appear in one of 6 locations. If the infant moves their gaze to the correct target location prior to the emergence of the cartoon character then they receive an audiovisual reward. For the first 8 trials, the character appears in a sequence of locations 1, 3, 5. After 8 trials the sequence reverses. The dependent variable is the proportion of correct anticipatory saccades towards the target location.

Visual paired comparison adapted from [52]

The infant is presented with a static image (Image A) in the centre of the screen. Image A is presented until the infant has looked at it for a total of 10 s. Following this 10-s period, Image A is presented alongside a new image, Image B. The dependent variable is the infant’s look duration towards the new versus the familiar stimulus.

Distractor adapted from [53]

An animated cartoon is presented in the centre of the screen. Throughout its presentation, distractors randomly appear on the left or right side of the screen. If the infant looks towards the distractors then the cartoon is paused. The dependent variable is the number of looks towards the distractors.