I begin with the following thesis:"ADD" is a modern concept. That is to say, the idea that it constitutes a "disorder" is a consequence of living in our modern society that imposes certain norms, rewards certain behaviors, and punishes others. A society organized differently, say one that rewards an ability to multitask and punishes an inability to absorb and process information from multiple sources simultaneously (or rapidly in seriatum) would characterize people who do well when concentrating as suffering from "sustained attention disorder" (SAD). In this sense, ADD is different from mental illnesses and disorders that are dysfunctional in all, or nearly all, societies (e.g., schizophrenia. Yes, in some societies suffering from auditory or visual hallucinations would make you a prophet -- but even in those societies such cases are outliers.) But it also means that our adaption to new technology is no more or less detrimental than how previous changes have shaped us, our brains, and how we absorb information.
We have reams of studies that show us that different people -- particularly children -- absorb information in different ways and through different strategies. Some do better in deep concentration mode, others do better with constant stimulation. Most human beings are flexible and trend to the center of the curve. They will do approximately as well with any of a number of methods -- whether it is the Socratic stimulation method roaming wherever it will, to a more physical use of manipulables we used for apprenticeship training, or modern 'sit-on-your-tush-and-pay-attention' style -- and will adapt to whatever is the dominant method. Some folks will do particularly well with a given method and/or particularly poorly with other methods.
For most of human history, these distinctions didn't matter. Enter the industrial age, the rise of mass production, and the concomitant rise of standardization in most human endeavors. Public schools are factories because that is what the industrial age required. It allowed us to mass produce education and deliver it to more children than ever before in human history. But that came at the price of adopting simple, standardized solutions that could fit within institutional constraints that -- for reasons that are too lengthy to go into here -- work against the stated goals of the education system.
Relevant for this discussion, however, is that the modern elementary, middle and high school systems as practiced for 100+ years rewarded ONE specific strategy -- the ability to process and retain information as a single stream, re-enforced by concentration. For about 100 years in the United States, this has been the dominant mode of training people to think. So much so that it has become the only way (or at least, the only accepted way) for the vast number of people in the system. Indeed, we train children from the time they are small that they must "learn to concentrate" because they will "need" to concentrate to learn as they get older, because more complex subjects require "more" concentration. We thus carefully re-enforce and reward all educational pathways that encourage "concentration" and punish with increasing frequency any effort to multitask -- because we "know" that this is the "only" or "best" way to learn.
Further, the system is self-re-enforcing because the brain is a flexible system and will respond to positive and negative stimulus and because when we survey the outcomes of the education system we see that those who learn to learn in the approved manner succeed. Those who adapt successfully to the dominant mode succeed. Those who cannot fail. This proves that the dominant mode is the "right" mode because it demonstrably produces success. Further, because the dominant mode is the single most mass produced thing in our society, there is almost no escape from being trained to think in this fashion. (Although the handful of alternative education institutions and home schooled children demonstrate that alternative modes of thinking can be successful.)
No surprise that subsequent testing of adults shows that generally people think best when not distracted and capable of deep concentration on a single stream and that when you force them to operate in conditions for which they are not prepared and not trained (a modern environment with distractions) they operate less well. After being thoroughly trained in one system, the brain reflects this conditioning in the same way that people who do weight training will have well developed muscles but may not be particularly good runners -- even though both are good forms of exercise and produce overall benefits to health.
This is also why "Attention Deficit Disorder" is a "disorder" for those at the far end of the curve who cannot successfully adjust to the dominant mode. The education system rewards a set of behaviors, punishes those that do not conform. Take two kids, one ADD and one "neurologically normal," and plop them down in a rural environment 200 years ago. Odds are good they would both get along reasonably fine depending on their finding a job suited to their specific talents and in an environment generally tolerant of individual variation. Tom ADD might be impulsive or easily distracted, but no one would think of him as suffering from any kind of disorder. Put them in a modern environment which must require conformity along particular lines of behavior and suddenly Tom ADD stands out because he spends the bulk of his childhood in an environment to which he cannot adjust.
Technology _is_ changing this by rewarding both Tom ADD, while mildly punishing "neurologically normal" folks all trained in one specific way of thinking. Tom ADD actually _does_ multitask effectively. At last, the world has finally shifted away from the conformity of the industrial age model and inputs come in constantly from multiple streams. (As I often tell teachers, you can tell the real ADD kids from the kids with short attention span because they actually do _well_ in the multitasking environment.) Joe Asperger also gets rewarded (depending on where he falls on the Autistic scale), because systems have become so complex that the ability to look at them from an alternate perspective has advantages. Neurologically Normal Norman, however, is at a disadvantage. All the skills he learned, and the neurological pathways optimized after years of training in one specific mode of thinking, are no longer the best optimized for the environment. Neurologically Normal Norm, however, now needs to artificially create an environment so that he can think and operate in the manner in which he has been trained.
I predict that, thirty years from now, when technology that rewards multiple stream processing is ubiquitous, educational norms will be optimized on the assumption that children learn best in a dynamic, changing environment that will give them the ability to multi-task that they will "need" when they reach adulthood. And because human brains are adaptable, the vast majority of children will adjust and consider this "normal." Those at the far end of the curve, who learn best in a single stream, will be diagnosed with "Sustained Attention Disorder" (SAD). There will be much discussion of these "slow" students who -- while extremely bright when focused on a single thing -- are simply unable to or unwilling to process information when it comes at them in multiple inputs.