Effects of the short-term learned significance of task-irrelevant sounds on involuntary attention in children and adults.

The present study aimed to test effects of unexpected task-irrelevant environmental sounds, that were short-term learned to be significant, on deviance-related brain activity (event-related potentials; ERPs) and performance in children aged 9-10 years and young adults. Participants performed three conditions. In the first ignore condition an oddball paradigm was presented including two neutral deviant sounds. In the second learning condition significance was attributed to one of the two deviant sounds by defining it as target. In the third condition participants then performed a version of an oddball paradigm, embedded in a narrative, that included the neutral and the now significant but task-irrelevant deviant sound. Results revealed decreased reaction times and hit rates elicited by significant compared to neutral deviant sounds in both age groups whereas P3a, an indicator of orienting of attention and novelty evaluation, was not affected by deviant's learned significance. In contrast, post-deviant processing, reflected by hit rates and ERPs in trials following a significant deviant compared to those following a neutral deviant, was differently modulated in children and adults. Moreover, a clear P3a was observed in the attend condition in both age groups but in the ignore condition in children only. Results indicate that the short-term learned significance of task-irrelevant sounds modulates performance but not orienting and evaluation processes associated with the P3a. Importantly, results demonstrate children's increased susceptibility to task-irrelevant but significant sounds and the ongoing maturation of attention control in the late childhood.