A number of years ago I began the search for structure within hemispheric processes by administering moderately large sets of lateralized tasks to the same subjects and factor analyzing the results. To date 14 such processes have been identified, some of which can be related to neuropsychological literature indicating approximate localizations in the cerebral cortex.
The tasks essentially constitute a test battery of lateralized function,
and Lindsey Adair used it in her Masters thesis research to find
that middle school children with Attention-Deficit/Hyperactivity Disorder
(ADHD) show specific problems with attentional processes in the frontal
and parietal lobes. Yet Anne-Marie Joubert showed in her Honors thesis
research that the parietal lobe problem disappears by early adulthood. Similarly,
Tanya Turan and I applied the battery to a sample of adult developmental
dyslexics. Counterintuitively, we found that dyslexic readers show normal
lateralization where one might expect unusual results (i.e., in visual
lexical processing), but lateralization the reverse of that in normal readers
in spatial quantitative processing. The result has some potentially important
implications for understanding cortical development, and particularly
the influence of one brain area on another during development.
Spatial quantitative processing is interesting, because the same process
appears to underlie our understanding of bargraphs and our understanding
of the numbers represented by dot clusters like those on dice. Research
I've recently completed with Jeff Phillips and Somer Shandy
shows that a kind of fast counting is involved in spatial quantitative
processing, either "stepwise" in bargraphs or of dots in dot clusters.
At the same time we have been examining the impact of the lateralized processes we've identified, on human performance. Processes possess resources, and tasks using similar resources interfere more than those that don't. This enabled development of an instrument called the Multiple Resources Questionnaire (MRQ) to measure the resources used by tasks. With other students, Lindsey Adair, Jeff Phillips and I have confirmed that the questionnaire approach works: Overlap in resources as quantified by the MRQ predicts the amount of interference between simultaneously performed tasks, whether the tasks are simple laboratory exercises or more complex video games.
Finally, my work indicates that practice can occur within resources, so that training a target task can partially proceed by practicing a different task with the same resource profile. In practical terms, this "resource training" suggests that the danger or expense of training a target task on-line or using high- fidelity simulation can be substantially reduced by substituting a simpler task with a similar resource structure.
To learn more about my work, please visit the Cognitive Neuroscience
Lab page for some of our recent activities.