It's certainly true, in my experience, that trying to do two or more things "at once" disrupt my focus and increase my error rate, but I think that high level gloss on the situation is unhelpful for technology workers.
Of course, if I ever had the opportunity to work on a single task, I can be very productive at that. Easiest way to get into flow state. However, that isn't common for my work. Often, instead, I am working on something that crosses many boundaries and has unavoidable downtime. For instance, right now I am working on visualizing erlang processes using Phoenix and d3js to see if I can detect unusual memory use growth. I'm going back and forth between erlang docs and Phoenix views and elixir code and javascript (with, of course, lots of reading and searching in between). I have no idea if that's multitasking, but when I have to move from one layer to another I experience the same kind of disruption and need to refocus as I do when I'm interrupted.
Another quality of multi-tasking that I frequently experience is the difference between needing to respond to external stimulus v.s. being able to orchestrate multiple processes to run in parallel. They both involve context switching and loss of focus, but there are huge differences in the order of magnitude.
Of course, if I ever had the opportunity to work on a single task, I can be very productive at that. Easiest way to get into flow state. However, that isn't common for my work. Often, instead, I am working on something that crosses many boundaries and has unavoidable downtime. For instance, right now I am working on visualizing erlang processes using Phoenix and d3js to see if I can detect unusual memory use growth. I'm going back and forth between erlang docs and Phoenix views and elixir code and javascript (with, of course, lots of reading and searching in between). I have no idea if that's multitasking, but when I have to move from one layer to another I experience the same kind of disruption and need to refocus as I do when I'm interrupted.
Another quality of multi-tasking that I frequently experience is the difference between needing to respond to external stimulus v.s. being able to orchestrate multiple processes to run in parallel. They both involve context switching and loss of focus, but there are huge differences in the order of magnitude.