Time Perception Deficits and Behaviors of Children and Adolescents With Attention-Deficit/Hyperactivity Disorder

BACKGROUND Children with attention-deficit/hyperactivity disorder (ADHD), a common, impairing neuropsychiatric disorder, are more likely to have difficulties planning and organizing. They cannot do things in an efficient way, cannot feel the limit of time schedule, and have difficulties awaiting their turns (Barkley, 1998). They often spend much longer time in homework, forget to accomplish routines or prescheduled work. Such behaviors often result in conflicts in the parent-child relationship.

In order to measure time perception, Barkley et al. (1997) developed two rating scales to evaluate children's sense of time and their ability of time management. They found an association between ADHD and poor time management. Barkley's (1998) comprehensive model suggested that time perception deficits in children with ADHD are due to deficits in behavioral inhibition and executive functions. Barkley et al's time reproduction tasks showed that children (1997), adolescents and young adults (2001) with ADHD had significantly more errors.

Recent studies focused on the associations of time reproduction with sustained attention, working memory, and behavioral inhibition. Kerns et al. (2001) reported a positive association between performance on a measure of attention (CPT) and a time reproduction task with a mixed result on the relationships between time reproduction and inhibitory control and working memory. McInerney and Kerns (2003) found the associations of time reproduction with working memory and behavioral inhibition, which lend support to the notion that time reproduction requires executive functions.

Smith et al. (2002) found that children with ADHD are more impaired in time discrimination threshold and less sensitive in fine time perception. This finding was later supported by Toplak et al (2003, 2005) using different modalities such as visual and auditory stimuli.

All the time perception tasks require the ability to allocate attention; however, different tasks involve other different mental abilities for estimation of duration of presentation of a target. Verbal estimation task is more related to the length of one's subject time unit, as synonymous inner clock speed. Time discrimination and time reproduction are related to the duration comparison. In addition to estimating the duration in the time discrimination task, subjects need to allocate their attention for a longer time and then to produce a target with the same duration by using some executive functions such as behavioral inhibition, sustain attention and working memory.