The relationships between drug use, task-unrelated thoughts (TUTs), self-reported sensation seeking, retrospective self-reported personality characteristics, laterality, eye dominance, and allergies in collegestudents who were diagnosed in childhoodas having attention deficitlhyperactivity disorder (ADHD) was investigated. Three groups (high-and low-activity and ADHD subjects) reported both spontaneous and deliberate TUTs during a vigilance task. Intrusive thoughts were found to be predictive of drug use/attitudes, but, to a greater extent, sensation seeking accounted for most drug-related behavior. Left-eye dominance was related to increased childhood hyperactive behaviors and to spontaneous TUTs. Of the three groups, subjects diagnosed as having ADHD had more spontaneous TUTs. These results are consistent with biological models.A recent research report has demonstrated a relationship between attention deficit/hyperactivity disorder (ADHD) and spontaneous thoughts (Shaw & Giambra, 1993). Another recent study has provided evidence that adult ADHD individuals are prone to drug and alcohol use (Mannuzza et al. , 1991). A plausible implication of these two studies is that ADHD persons wish to stop the discomfort of unbidden thoughts. This suggested relationship deserves investigation .The main findings of Shaw and Giambra (1993) were that subjects diagnosed with ADHD as children exhibited the greatest frequency of spontaneous thoughts , left-eye dominance , and sensation seeking. Shaw and Giambra (1993) stated that our ADHD individuals , hypoaroused and seeking optimum levels of sensation (or perhaps increasingly aroused because boredom is extreme ly stressful to them) have higher levels of nonconscious processing (from fleeting sensory input and/or previous thought ) and subsequent semantic activation . The results of these processes emerge rapidly into consciousnes s as spontaneous thoughts. In ADHD individuals, the uncontrolled spontaneous thoughts may be disrupting attention such that they cannot concentrate on the task at hand. In other words , when ADHD individuals are bored their semantic activation processes seem more random and may cause mental discomfort to these individuals resulting in poor coordination of attentional and inhibitional processes . (p. 28)The two general theories used by Shaw and Giambra (1993) to explain intrusive thoughts in ADHD persons involved arousal levels and impulsivity. Klove (1989) cites a great deal of evidence supporting the hypoarousal hypothesis, which states that ADHD children seem to need stimulation as a result of underarousal in the reticular activating system and cortex. Zuckerman (1979Zuckerman ( , 1983 We are grateful to L. M. Giambra and E. Rosenberg , of the National Institute on Aging, for allowing us to use the computer task, and to the students who served as our subjects. Requests for reprints should be sent to G. A. Shaw, Department of Psychology , Georgetown College , KY 40324 .views sensation seeking as a stable, biologically based personality trait defined a...