The task of finding a case type that, on average, enhances the processing of verbal material has yielded mixed results in the literature. This study tackled this issue with an eye to the issue of processing textual information on road signs and the additional consideration of readers’ attentive states. Participants (n = 104) completed three experiments, the first two of which made use of both short (i.e., attentive state) and long (i.e., nonattentive or mind-wandering state) inter-trial intervals (ITIs). Experiment I consisted of a living versus non-living category-decision task involving the presentation of single words. Experiment II consisted of a sensical versus nonsensical sentence-judgment task. Experiment III consisted of a recognition memory task for words presented during the category-decision task. No significant difference in letter-case-type effectiveness was found for either the semantic categorization of or memory for single words. On the other hand, sensical sentences were correctly judged more quickly in lower case (or, more precisely, sentence case with the first letter of the first word capitalized). Such results point to either a more fluent processing of or enhanced conceptual resonance for sentences presented in lower case.

Mind wandering, emotional lability and sleep quality are currently mostly independently investigated but are all interlinked and play a major role is adult attention-deficit/ hyperactivity disorder (ADHD). Emotional lability is a core feature of the disorder, excessive mind wandering has recently been linked to symptoms and impairments of ADHD and poor sleep quality is experienced by a clear majority of adults with ADHD. All three phenomena lead to functional impairment in ADHD, however their relationship to each other and to ADHD symptom severity is not well understood. Here we used serial multiple mediation models to examine the influence of mind wandering, sleep quality and emotional lability on ADHD symptom severity. 81 adults diagnosed with ADHD participated in this study. We found that mind wandering and emotional lability predicted ADHD symptom severity and that mind wandering, emotional lability and sleep quality were all linked and significantly contributed to the symptomatology of adult ADHD. Mind wandering was found to lead to emotional lability which in turn lead to ADHD symptom severity; and poor sleep quality was found to exacerbate mind wandering leading to ADHD symptoms. Future research should employ objective on-task measures of mind wandering, sleepiness and emotional lability to investigate the neural basis of these impairing deficits in ADHD.