| Summary: | Attention-Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent disorders diagnosed in
children. However, less is known about the clinical manifestation of the disorder in adults and the impact
thereof on for instance social and occupational functioning. With respect to temporal perception deficits in
both child and adult ADHD, contemporary findings have produced mixed results. In line with this, the
current investigation aimed to identify whether young adults who possess significant ADHD symptomology
have pure time perception deficits and/or differences in self-reported habitual time perception.
Stratification of the ADHD and non-ADHD group was achieved using the Adult ADHD Self-report Scale
(ASRS V1.1). Between group differences in self-reported temporal orientation was investigated using the
Zimbardo Time Perspective Inventory (ZTPI). These outcome scores were compared using an ANOVA.
The investigation into pure psychophysical time perception was conducted on a sub sample of that used in
the self-report investigation. The ADHD group consisted of 12 participants whereas the non-ADHD group
consisted of 10 participants. These two groups conducted temporal estimation and temporal discrimination
tasks. Between groups, performances on these tasks were compared using an ANOVA.
In addition to this, electroencephalography (EEG) recordings of frontal, frontal midline and parietal activity
during resting states and task performance were conducted. This allowed for between group comparisons
in absolute and relative power scores at four different frequency bands (delta, theta, alpha and beta) to be
made. A non-parametric Mann-Whitney-U test was used in this regard. The same statistical technique was
used to compare the theta/beta ratios elicited by the resting state and temporal perception conditions.
Results showed that those with significant ADHD symptomology have a characteristically different selfreported
habitual time perception. This is illustrated by negative thoughts towards past and present life
events, and an absence of future orientated behaviour.
In terms of the objective psychophysical measures, the current investigation found no group differences in
estimation or discrimination task performance. Despite this absence of difference, the group with significant
ADHD symptomology showed significantly different EEG recorded neural activity, during resting states and
during task performance. The nature of this activity was in line with a generalised cortical under arousal
hypothesis of ADHD. Taken together, these findings indicate that individuals with significant ADHD
symptomology do not only consciously perceive time differently to those who do not have significant
symptomology, but also show different neuro-physiological processes when performing tasks that require
the utilisation of temporal processing mechanisms. In this way, the findings provide insight into possible
objective measures that could be utilised in ADHD diagnosis.
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