was significantly higher or lower than would be predicted. A baseline prediction could be taken by comparing the scores of groups a and B, and then comparing the scores of group B. And D. If AD/HD had no unique effect on multi-tasking, then one would expect the same ratio to exist between multi-tasking groups as between single-tasking groups. For example, imagine that group a averaged a "danger score" of ten, and the average group B. driver score was five. Further imagine that the average group D score was seven. One would then expect that group C. would be double that and have a score of fourteen. If their actual score was either significantly lower or higher than that, this might indicate that AD/HD had a specific effect not just on the ability of the individual to drive in all conditions but also specifically on their ability to drive while multitasking. If the score was lower than fourteen, it might indicate that controlled distractions were not as damaging to AD/HD drivers as to others. If it was lower than ten (e.g., lower than the score of the single-tasking AD/HD drivers) then this would indicate that such distractions were actually beneficial. If the score were higher than fourteen, on the other hand, it might indicate that multitasking was even more dangerous for AD/HD individuals than for others. A similar dynamic would exist even if the average multitasking score for all drivers was more comparable (or even lower) than the average single-tasking scores.
In short, if drivers show a lower danger score while multi-tasking, it indicates that the minor tasks they undertake are actually helping them keep their attention focused in the car and the driving experience rather than taking off in daydreams or other concerns. If they show a higher score, it means that the multi-tasking distracts negatively from the driving. If all categories perform better while multi-tasking, this positive distraction would be a universal human trait (and likewise if all performed worse). If AD/HD drivers perform significantly better or worse than the baseline in this area, then this speaks to their unique needs. If group C. performs better than group a, then this shows that individuals with AD/HD actually drive better with distraction. Even if C. performs less well than a, if group C. performs better than group D. Or better than the baseline would have suggested (that is, if a / B > C / D), then this shows that AD/HD drivers deal better with multi-tasking than do regular drivers. On the other hand, if group C. performs worse than all the other groups and worse than the baseline would have suggested, then this show that multi-tasking is harder for AD/HD drivers than for other drivers. If the baseline is consistent, or (which is unlikely) there are no significant differences between AD/HD and non-ADHD drivers, then this shows that AD/HD does not have a significant impact on multi-tasking skills while driving.
To summarize, if the generic hypothesis is true, then a / BC / D. That is to say, Group C. will either perform much better or much worse than expected from single-task comparisons, proving that AD/HD does have some affect on the multi-tasking abilities of drivers. If they perform better than expected, this helps to prove the second hypothesis that AD/HD helps with multi-tasking, and if group C. actually outperforms groups a, B, or D. It will show that multi-tasking may overcome AD/HD symptoms. Alternately, if they perform worse than expected, it will help illustrate the "alternative" hypothesis that AD/HD makes multitasking harder. In either case, unless there are no differences between the ratios present with a and B, C and D, the generic hypothesis will be shown.
Goepel, J. (2003, May) "Crashes caused by inattentive drivers are nothing new. Cell phones are the latest distraction." VIA. http://www.viamagazine.com/top_stories/auto/cell_phone03.asp
Living with ADD. (2004) http://www.livingwithadd.com/
Snyder, M. (200) ADHD & Driving: A Guide for Parents of Teens with AD/HD. Montana: Whitefish Consultants.