A few weeks ago I wrote on the Onlignment blog about The multitask assumption. By this I meant the assumption you can safely make with any webinar that a good proportion of the audience is multitasking - you know, checking emails, answering the phone, listening to music, finishing off a report, and so on. Well, on the basis of recent research, I think it's fair to challenge that assumption. Your webinar audience might think that they're multitasking, but they're not. Humans can't multitask, they can only switch from task to task, and they do this relatively poorly.

Yes we can multitask as long as only one of those tasks is making use of our working memory. We can walk and talk at the same time (because the walking's automatic), but we can't talk and listen. The conscious part of the human brain works sequentially, one task at a time. Computer processors are much the same. The difference is that computer processors can switch from one job to another millions of times a second. whereas human brains take a second or two to switch attention. That's why computers can be said to multitask, and humans can't.

According to work conducted at Stanford University and reported by Constance Holden in ScienceNOW Daily News under the heading Multitasking muddles the mind, "cognitive performance declines when people try to pay attention to many media channels at once." Clifford Nass, co-author of the study, claims "the study has a disturbing implication in an age when more and more people are simultaneously working on a computer, listening to music, surfing the Web, texting, or talking on the phone. Access to more information tools is not necessarily making people more efficient in their intellectual chores." Also disconcerting, he notes, is that "people who chronically multitask believe they're good at it."

Technology invites us to try and multitask in ways that would never have been practical in years gone by. Our computer operating systems assume we'll be working on more than one activity at a time - that's why Microsoft calls theirs Windows and not Window. Tiny devices that we can carry around in our pockets provide us with the ability to receive voice, text, picture and video messages at any time and anywhere, and so we do. Twenty-first century culture makes us feel that we should be multitasking, because that's the cool and contemporary thing to do. And digital natives even believe that their brains have been specially trained to multitask, because that's what Mark Prensky told them years of videogaming had achieved.

Switching attention from one stimulus to another may be due to excess capacity; we've all attended presentations which move at too slow a pace, leaving our brains with plenty of scope for thinking of other matters. On the other hand, task switching may just be down to sheer laziness - after all, concentrating is hard.