Inattention and proclivity for distraction are symptoms of adult ADHD that hamper productivity in study and work environments. The topic of this dissertation is mechanisms of distraction and facilitation of attention in ADHD. This thesis includes three studies. The following overarching questions are addressed in each study respectively: (1) Is computerized cognitive training (CCT) an intervention which improves overall cognitive outcomes in adults with ADHD, (2) Are there differences depending on ADHD symptom severity and distraction in auditory or vibro-tactile sensory modalities, and (3) Is background white noise a shield from distraction for those with ADHD during a short-term memory task?

Study I is a systematic review and meta-analysis of CCT interventions for adults with ADHD, following a pre- post-test design for randomized controlled trials. Nine intervention studies are included in the systematic review, with the resulting meta-analysis for overall cognitive outcomes showing a very small benefit of the CCT intervention. Study I also included sub-analyses of three outcome categories according to the Cattell-Horn-Carol framework of cognition: cognitive speed, executive functions, and short-term memory. None of these individual meta-analyses resulted in significant improvements. 

Participants took part in a cross-modal visual oddball task with auditory and vibro-tactile distractors in Study II. Forty-five participants were divided into two groups for the analysis: one group with low ADHD symptoms and one group with high ADHD symptoms. Findings did not show a relationship between ADHD symptom status and distraction in either auditory or vibro-tactile modality, despite both groups showing the expected slowed reactions on deviant trials. A sensitivity analysis showed that the high symptom group exhibited 0.5 % more missed trials compared to the low symptom group, possibly due to mind wandering in this non-forced-choice task.

For Study III, serial recall data was collected from sixty-six individuals with ADHD and sixty-six healthy control participants, who were tested with white background noise and no background noise conditions. The results showed that participants with ADHD were more likely to get distracted by auditory omission deviants in continuous background white noise, whereas healthy controls were more likely to get distracted by auditory addition deviants in the condition without background noise. Also, the individuals with ADHD on average did not exhibit a typical primacy effect across serial recall items. Overall, the results of the three studies in this dissertation point to some areas for improvement for adults with ADHD where targeted behavioral interventions might be useful in the future.