Saliency Models Reveal Reduced Top-Down Attention in Attention-Deficit/Hyperactivity Disorder: A Naturalistic Eye-Tracking Study.

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent neurodevelopmental disorder. It is associated with deficits in executive functions, especially in visual attention. Deviant visual attention in ADHD is suspected to arise from imbalances between top-down and bottom-up mechanisms. However, it is unclear which of these mechanisms propels the aberrant visual attention.

METHOD

In 815 medication-naïve children and adolescents (age range 5-21 years), differences in visual attention in participants with ADHD and neurotypical controls were investigated using eye tracking in a naturalistic video viewing task. Two opposing saliency models were used. Finegrained, based on low-level image features, was chosen to estimate bottom-up visually relevant areas. ViNet, a higher-level saliency model based on deep neural networks and trained on the gaze of neurotypical controls, was selected to determine top-down visually relevant regions. Correspondence between gaze and both saliency maps was calculated using normalized scanpath saliency, thus measuring the extent of coherence to bottom-up and top-down relevant contents.

RESULTS

Participants with combined ADHD showed lower mean normalized scanpath saliency for the top-down saliency map, but not the bottom-up one, compared with neurotypical controls. This contrast indicates poorer top-down control as a major contributor to impaired visual attention in combined ADHD. There was no significant effect for the predominantly inattentive ADHD group.

CONCLUSION

This study demonstrated the use of eye tracking for differentiating between top-down and bottom-up visual attention. It shows that in combined ADHD, a reduction of top-down visual attention is key to an impaired competition between bottom-up and top-down visual attention.