The effect of audiovisual integration on oculomotor inhibition of return in children with attention-deficit/hyperactivity disorder

The two-component theory posits that the inhibition of return (IOR) consists of a perceptual component for manual responses and a response component for saccadic responses. Research has shown that abnormal audiovisual integration in children with attention-deficit/hyperactivity disorder (ADHD) limits the attenuation of manual IOR, suggesting that their audiovisual integration deficits manifest at the early perceptual stage. However, since manual responses inhibit the activation of the oculomotor system, it remains unclear whether the abnormal audiovisual integration in children with ADHD extends to the late processing stage. The present study adopted the cue-target paradigm to investigate the impact of audiovisual integration on oculomotor IOR (O-IOR) in children with ADHD, aiming to reveal whether their audiovisual integration deficits primarily occur at the early perceptual stage or also involve the late response stage.Experiment 1 employed divided modality attention (simultaneously attending to visual and auditory targets and making saccadic responses). We manipulated the variables of group (ADHD children vs. typically developing [TD] children), target type (visual vs. auditory vs. audiovisual), and cue type (cued vs. uncued). Experiment 2 was similar to Experiment 1, but participants were instructed to ignore the auditory stimuli. Therefore, the target type included only two levels (visual vs. audiovisual). By using modality-specific selective attention to constrain early audiovisual integration, Experiment 2 further investigated how late audiovisual integration affects O-IOR in children with ADHD when early integration is restricted, thereby revealing whether their audiovisual integration deficits involve the late response stage.The results of Experiment 1 found that the audiovisual O-IOR in TD children was significantly smaller than the O-IOR under single modal conditions, whereas this difference was not observed in children with ADHD. Furthermore, audiovisual integration occurred under the cued condition in TD children but not in children with ADHD. This indicates that audiovisual integration attenuated the O-IOR effect in TD children, while children with ADHD exhibited abnormal audiovisual integration, lacking this attenuating effect on O-IOR. The results of Experiment 2 found that the audiovisual O-IOR in both children with ADHD and TD children was significantly smaller than the O-IOR under single modal condition. Moreover, audiovisual integration occurred under the cued condition in both groups. This suggests that when early integration is constrained, children with ADHD can still exhibit the attenuating effect of audiovisual integration on O-IOR, revealing that their late audiovisual integration processes are preserved.In summary, the present study demonstrates that the audiovisual integration deficits in children with ADHD primarily occur at the early perceptual stage, while the late response stage is intact. These findings provides a new perspective for understanding the stage-specific characteristics of multisensory integration in children with ADHD.