On Friday in Des Moines, First Lady Michelle Obama incorrectly referred to Democratic Senate candidate Rep. Bruce Braley as “Bruce Bailey” several times. A video of the event surely made Democratic operatives cringe and Republicans fist-bump, while the media saw a juicy story.

Meanwhile, cognitive scientists, psycholinguistics and cognitive neuroscientists just nodded and smiled.

It turns out that these kinds of slips of the tongues, or "spoonerisms," as they're called, are surprisingly common, and reveal a lot about how our brains organize and process language.

The first thing to know is that producing a word is hard. Most people know more than 60,000 different words, and well-educated folks like Michelle Obama may know more than 100,000. To construct a sentence is to choose a few words from this paralyzing array of choices, and to do it at a rate of 3-4 words per second! Moreover, each word requires a speaker to coordinate a five to six different parts of your vocal tract (tongue, lips, larynx, etc.) with millisecond precision.

The fact that we’re able to get a word out at all is an extraordinary feat.

This second thing to know is that these decision processes occur as a sort of competition. The brain selects many candidate words, and they compete over time until one wins. For example, if you were trying to talk about your living room, you might consider both the words sofa and couch, or even less common ones like davenport. Over time, these options compete until one wins, the one you end up saying.  Of course, this competition is playing out over 60,000 potential candidates.

How our brains process words

It’s difficult to visualize this competition in studies of how people produce words, but it’s easy to visualize it when we think about understanding them. In the lab, we can present a simple word like rocket, and have participants select the matching picture from a screen that contains a picture of a rocket, a picture of a similar sounding word like a robin, and some other objects. A mere 200 milliseconds after the participants have heard “ro-”, they’re already making eye-movements to both the rocket and the robin. That is, they’ve already started partially considering both words. If we follow their eyes through several hundred milliseconds, we can see other words — like the rhyming word “pocket” — start to gain steam before ultimately rocket wins.

The following graph shows that as milliseconds pass, our mind starts to focus on the right word, but at the beginning there are several competing words that we can select from.

Slide1

The crucial thing about this competition is that it isn’t orderly. The word that makes the most sense doesn’t always win, particularly in a challenging situation like speech production. It’s more like a PTA meeting or the Iowa Caucuses than a simple vote – lots of noisy interactions from multiple parts of language

Importantly, for the case of Michelle Obama, words that are more common--or better learned--have the edge, even as this must be balanced with lots of other factors. Thus, a more common name like Bailey, might win out over a less common one like Braley. Bailey, after all, is around the 66th most common surname in the U.S., while Braley is closer to the 8000th.

But if the most common words have an edge, why did Bailey win the competition in the first lady’s head over an even more common name like Miller (6th most common)? And what was Bailey doing in this competition at all? There weren’t any Baileys present, and Obama surely knows Braley’s name.

Well, at the same time that this competition is brewing among words, other things are happening too. Most importantly, people need to start planning their physical production of the sounds, and the motor system can’t wait for this competition among words to finish or people would speak way too slowly. So, even as sofa and couch are duking it out to be the winner, the brain is already planning what the mouth, vocal chords and the rest of motor system must do to say both.

So, how do you finally say a word?

As the brain weighs different options for a word, the production systems for specific sounds start sending signals back to the part of the brain trying to select the right word. These signals have a little input on which word is ultimately selected. This is helpful: it ensures that the selected word matches the selected motor commands. It’s a way of checking that all of the parts of this noisy competition are working together: Otherwise you might say “cheese” when you think “bread.”

So when Michelle Obama activates “Braley,” there might be a little competition from other words meaning similar things: Bruce (the congressman’s first name), Loebsack (the other congressman from Eastern Iowa). As Braley starts to win, it starts to activate the motor commands to say a “b”, “r”, “ay”, “l” and “ee”. And then the motor system sends a message back to the part of the brain where words are competing to activate other similar sounding words … like Bailey. Since Bailey is more common than Braley, once in a while, or unfortunately for Michelle Obama -- thrice in a while — it wins.

Slide2

Cognitive scientists describe this process with the metaphor of interactions among networks of neurons. Populations of cells corresponding to words send activation (neural firing) to populations of cells corresponding to the speech sounds they require. Activation flows back and forth between levels until a winner is established. These activation networks have been implemented computationally by people like Gary Dell at the University of Illinois, and do a pretty good job predicting the kinds of speech errors people make. Interestingly, this exact same mechanism also offers a nice account of all sorts of other abilities: how people make decisions, categorize objects, perceive speech, process music, and even how children learn new words. That is, these embarrassing speech errors may be an unavoidable consequence of the general principles by which the brain processes information.

So to Braley and Obama, the field of Cognitive Science and your brains apologize for this embarrassing lapse. But to students of the mind everywhere, nod and smile. Competition happens not only between politicians, but even in their own minds.

Bob McMurray is associate professor in the Department of Psychology, the Department of Communication Sciences and Disorders and the Delta Center at the University of Iowa.

Sources:

1. More information on Spoonerisms here: http://en.wikipedia.org/wiki/Spoonerism

2. The eye-tracking technique was first reported in Tanenhaus, M. K., Spivey-Knowlton, M. J., Eberhard, K. M., & Sedivy, J. C. (1995). Integration of visual and linguistic information in spoken language comprehension. Science, 268, 1632-1634.

3. The figure comes from my own work using this technique where we actually applied this technique to understand children with language disorders: McMurray, B., Samelson, V. S., Lee, S. H., & Tomblin, J. B. (2010). Individual differences in online spoken word recognition: Implications for SLI. Cognitive Psychology, 60(1), 1-39.

4. The notion of interactive activation derives from seminal work from David Rumelhart and James McClelland (McClelland, J. L., & Rumelhart, D. E. (1981). An interactive activation model of context effects in letter perception: I. An account of basic findings. Psychological Review, 88(5), 375) and was first applied to speech production and speech errors by Gary Dell (Dell, G. S. (1986). A spreading activation theory of retrieval in sentence production. Psychological Review, 93, 283-321)