The Myth of Multitasking: Serial Attention

"Achtung!" --U2

Cognitive Science is awesome for (at least) two reasons. First, the field likes to debate all sorts of binary questions (e.g., Does the mind use symbols or not? When reading, do we process surface features or semantic features?). Second, cognitive scientists come up with all sorts of crazy metaphors to better understand the complex inner-workings of the mind. The topic today is awesome for both reasons. Early investigations into attention tried to answer binary questions, such as: Is attention parallel or serial? Does information get selected for deeper analysis early in the process or later? Also, they came up with some pretty cool metaphors to describe attention, such as switches, filters, attenuators, and spotlights. 

Before we dive in, let's make a distinction between information selection and information processing. We've all heard the phrase "selective attention" (or, the close cousin "selective hearing"). It seems that some people have an amazing ability to pay attention to only one thing at a time. For example, if your roommate is texting her friend, she might not even notice when you ask a direct question. When texting, your roommate has decided, consciously or not, to select the information emanating from her phone. Processing information, on the other hand, refers to the analysis and response to that information, such as a replying to a text message. 

Now that we've laid the groundwork, let's look at the fascinating world of auditory and visual attention! 

"Were you listening to me, Neo? Or were you looking at the woman in the red dress?" --Morpheus

So we know that deep down, at its core, the attentional system is massively parallel. It doesn't matter how engrossed you are in a task, you will respond to a very loud siren and a red flashing light. Not much analysis needs to take place because your attentional system is always on high alert to keep you alive. If something threatening comes your way, odds are your attention will be captured and you will respond immediately [1].

Going beyond all the loud noises and lights, the attentional system also has to be designed to help you select and process information. Most evidence suggests that there is a bottleneck somewhere in the attentional system such that, once selected, we can only process one stream of information at a time. In early auditory attention experiments, researchers asked people to listen to a recording where they shadow, or repeat, the message in one ear and ignore the message played in the other ear. You can try it for yourself here. After the task was over, the researchers asked about the information in the ignored ear. Most could say if the voice was male or female, and give other surface characteristics of the sound, but not much more than that (i.e., the content of the message). 

A similar finding has also been demonstrated for visual attention. Here is one of the coolest demonstrations of this phenomena. You need to experience it for yourself.

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Simon's Visual Cognition Lab

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This is a very powerful demonstration of the effect of a goal (e.g., count the number of passes) on the selection of information. It also demonstrates that we can only process one stream of information at a time. 

A STEM Example

I'll be honest, selectively attending to a single stream of information is one of the most fundamental principles of education. You can't learn what you don't pay attention to! That seems almost too simple to state, but it seems like it's easy to forget. 

Knowing that we are serial processors is useful when evaluating educational applications. A great example is duolingo, which is an app that teaches (or re-teaches) a second language. Each task is presented in a simple interface where the learner concentrates on only one goal at a time. Once that task is finished, the learner progresses to the next task. Again, the app keeps things simple and doesn't try to split the student's attention across too many sources of information. 


Share and Enjoy! 

Dr. Bob

For More Information

[1] The lone example I can think of are some Tibetan monks who are able to get deep into a meditative state where they do not respond to loud noises (see Chapter 1 in Search Inside Yourself for a description).