MP: This is probably less likely. It probably depends on how much you process this information. So I think that the key probably arises from exercise of the attentional networks, not just from exposure to flashing lights and so on. Because we’re pretty good at being able to, you know, tune out some of this. But, again, I don’t know… obviously, the more effective the ads are in getting in and getting some processing, the more they will probably take your sources and lead to a certain amount of fatigue.

RJ: Going back to the three aspects of attention—alerting, reacting, and executive—do we have an idea why our brains are this way? The evolution process or that sort of thing?

MP: So the evolution of these brain networks… two of them are extremely old; one of them, certainly the alerting network, goes back to the animal kingdom, and it has to do, of course, with the way in which the animals adapt to awaking and sleep and Circadian rhythms, the rhythms of the day and so on—these are ancient networks. Different animals have of course adapted in somewhat different ways. Why we change in alertness over the day, why we have a diurnal cycle and so on, I’m not really able to say.

There are quite a number of theories on why this is so, but it certainly is ubiquitous in the animal kingdom. The orienting network has been studied in all the way down to rodents and so on, and although there are certainly lots of differences that occur between rodents and monkeys, and then some differences between monkeys and humans, these networks have been preserved pretty well in evolution, probably because they work effectively. The executive network seems to have a very big change between primates and humans. There are cells available in the anterior singular in humans—and to a lesser degree in some great apes—that aren’t available in even other monkeys (non great ape monkeys). These cells provide greatly increased connectivity between the executive network and other parts of the brain, and that, I believe, underlies the human skill at self-regulation—although obviously we’re not as skillful as many of us would like to be, but in comparison to cats or other primates, we’re highly skilled at being able to bring a coherent focus of attention over relatively long periods of time, and this seems to be a late evolutionary adaptation, and probably is one of the things that make us human.

RJ: So it seems that some of these systems are ancient; some are, at least in evolutionary terms, pretty new. Where does that leave us in the 20th and 21st century, in the information society?

MP: Where does it leave us in the 21st century? Well, it’s hard to say. Definitely in a society in which there’s a lot of information available, and we should expect the human to continue to adapt to this, because although genetic adaptation is relatively slow and long term, many of the genes that we have that shape these networks are also influenced by our experiences—not the genes themselves, but their expression. And so we should expect exposure to the network—to increased information—to change the skills that people have. We can point to the advantages of those changes—perhaps in multitasking, that’s one that you discussed—and you can also point to disadvantages. People often use the term attention span, suggesting that we can’t sustain attention for long periods of time. I don’t know if there’s really any strong evidence for that, but there is a certain amount of plasticity in these networks, and that suggests that they’re adapting to circumstances that we’re in in this century.

RJ: Are there any specific genes or gene expressions that researchers are focusing on in this regard?

MP: Oh, yes. Well, we’ve worked on several genes that show influence. For example, style of parenting. For example, dopamine genes that interact with the style of parenting to shape aspects of the ability of people to, for example, their activity level and impulsivity and so on. So, yes, there’s increasing interest, particularly in dopamine and serotonin genes, in how their expression might be influenced by things that happen in the culture, or things that might be deliberately designed to improve performance by training.

RJ: To get back to one of the things you mentioned about attention span—do you see any trends in the media in changing attention span? Or do you think that’s just something that’s like a meme that maybe doesn’t have as much meaning as some people have—

Russ Juskalian is a contributor to The Observatory and a freelance writer.