Is attention impaired in ADHD?

Abstract

Explanations of Attention Deficit Hyperactivity Disorder (ADHD) in terms of a weakness in Executive Function (EF) or related concepts, such as inhibition, are briefly reviewed. Some alternative views are considered, in particular a proposal by Manly and others that ADHD is a weakness primarily of sustained attention (plus control of attention), but not of selective attention, as measured by the Test of Everyday Attention in Children (TEA-Ch; Manly et al., 2001). The underlying structure of the TEA-Ch is analysed and it is concluded that the distinction between selective attention, sustained attention, and control of attention in this battery is not well-founded. Furthermore, evidence from studies by Wilding and others, from visual search tasks similar to those employed by Manly et al. to measure selective attention, demonstrates that, while unimpaired- and impaired-attention groups do not differ in speed of performance on such tasks (the measure employed in the TEA-Ch), they do differ reliably in accuracy. Available evidence from other visual search tasks comparing such groups is reviewed and found to be inconsistent. An attempt is made to resolve the inconsistencies and it is suggested that search tasks including demands that engage EF processes are more likely to demonstrate differences between these groups. It is concluded therefore that the most plausible explanation at present of impaired attention is in terms of weaknesses in EF. Suggestions for improving the precision and detail of this type of explanation are offered.