-
[show abstract]
[hide abstract]
ABSTRACT: Individuals with attention-deficit/hyperactivity disorder (ADHD) often exhibit deficits in processing information about time. Most studies, however, have required participants to perform active tasks and consequently it is unclear if performance deficits are due to impaired processing of temporal information, attentional deficits, or to impairments at a later stage of decision-making. This study used mismatch negativity (MMN) to examine automatic processing of temporal information in children with ADHD. The sample consisted of 11 children with typical development (8 boys; mean age/SD = 9.3/0.6 years) and 12 with ADHD (10 boys; mean age/SD = 8.9/0.8 years). Using the MMN paradigm, responses to standards and four deviants (hard/easy frequency, hard/easy duration) were elicited during the same sequence. The children's ability to actively discriminate each deviant was also assessed. Both groups exhibited MMNs to all deviants suggesting successful automatic discrimination. Furthermore, amplitude and latency measures were roughly comparable across groups. No group differences were seen on the active discrimination task, but performance was worse for duration than for frequency deviants. These results suggest that children with ADHD are able to automatically process temporal information, so deficits reported in active discrimination paradigms are likely due to deficits in subjective perception or usage of temporal information. (JINS, 2013, 19, 1-9).
Journal of the International Neuropsychological Society 03/2013; · 2.76 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This study sought to better characterize the contributions of deficits in attention allocation and distracter inhibition to the poor performance on attention tasks often seen in children with ADHD.
Electrophysiological (Nd, P3b) and behavioral measures (speed and accuracy) were examined during an auditory selective attention task in children with ADHD, children with typical development (TD), and adults. Thirty children (15 ADHD; 13 females) between the ages of 7 and 13 and 16 adults (8 females) participated.
Nd waveforms were elicited from adults and children with TD, but not from children with ADHD. Further, those with ADHD exhibited significantly smaller auditory responses at 100 ms (Ta). P3bs were elicited in all three groups by targets but not by unattended deviants. Performance was significantly poorer in children with ADHD than TD and RTs were more variable.
Children with ADHD evidenced poorer attention allocation, as measured by Nd and hits, but were not more distracted by unattended deviants, as measured by P3b and false alarms, than children with TD.
Findings for Nd, P3b, and Ta considered together suggest that deficits in auditory selective attention in children with ADHD may be attributable to reduced information early in the processing stream.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 08/2011; 123(2):293-302. · 3.12 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We examined the impact of perceptual load by manipulating interstimulus interval (ISI) in two auditory selective attention studies that varied in the difficulty of the target discrimination.
In the paradigm, channels were separated by frequency and target/deviant tones were softer in intensity. Three ISI conditions were presented: fast (300ms), medium (600ms) and slow (900ms). Behavioral (accuracy and RT) and electrophysiological measures (Nd, P3b) were observed.
In both studies, participants evidenced poorer accuracy during the fast ISI condition than the slow suggesting that ISI impacted task difficulty. However, none of the three measures of processing examined, Nd amplitude, P3b amplitude elicited by unattended deviant stimuli, or false alarms to unattended deviants, were impacted by ISI in the manner predicted by perceptual load theory.
The prediction based on perceptual load theory, that there would be more processing of irrelevant stimuli under conditions of low as compared to high perceptual load, was not supported in these auditory studies.
Task difficulty/perceptual load impacts the processing of irrelevant stimuli in the auditory modality differently than predicted by perceptual load theory, and perhaps differently than in the visual modality.
Clinical Neurophysiology 04/2008; 119(3):542-55. · 3.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this study, we examined developmental changes in auditory selective attention using both electrophysiological (Nd, P3b) and behavioral measures while two groups of children (9- and 12-year-olds) and adults were engaged in a two-channel selective attention task. Channel was determined by frequency (1000 or 2000 Hz). Targets in one condition were shorter than the standards (duration target) and in the other were softer (intensity target). We found that the Nd onset and peak latencies for the children were significantly longer than for the adults. Nd amplitude, however, did not differ between the groups. Further, all groups evidenced P3b to attended targets but not to unattended deviants. Hits, reaction times, and false alarms to unattended deviants continued to evidence improvements through adolescence. Taken together, our data are most consistent with a model of developmental improvement in the speed and efficiency of attention allocation.
Psychophysiology 10/2007; 44(5):711-27. · 3.29 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Theories regarding children's reliability as witnesses suggest that children are more likely to confuse memories from different sources especially when the sources are highly similar. To investigate the developmental aspects of source retrieval, we measured brain electrical activity from children and adults while they retrieved content and source information. Similar brain responses among the age groups were found when participants were asked to retrieve content information. However, retrieval of source information improved with age and was accompanied by different patterns of brain potentials. The results implicate immaturity of frontal lobe structures in children's difficulty in retrieving source information.
Journal of Cognitive Neuroscience 08/2003; 15(5):759-68. · 5.18 Impact Factor
