Cognitive Daily

i-eca0cf2af9fc3ac4445c7dff7d8aab70-research.gifMost language processing takes places in the left hemisphere of the brain. When we read, carry on a conversation, or listen to speech, most of the action — for right-handers — takes place on the left side of the brain. (For left-handers, the situation is more complex; it’s not simply a mirror image of a right-handed brain. For this reason, most studies involving any sort of brain scan routinely exclude left-handers.)

But there are a few occasions when the right hemisphere gets involved: when we create a narrative, for example, or when we make inferences. Some types of figurative language, such as metaphor and irony, also involve the right hemisphere. But research on perception of metaphor and irony has had difficulty identifying differences in how the two processes work.

Arguably, there isn’t much difference between an ironic statement and a metaphor. Irony involves saying the opposite of what we mean (“George W. Bush is so smart!”), and metaphor involves using language that is not literally true (when we say “Donald Rumsfeld is a lightning rod for criticism” we don’t mean that we place him on top of tall, exposed buildings during thunderstorms).

Some theorists make a distinction between “conventional metaphor” and “novel metaphor.” Conventional metaphors are metaphors that are so common that they often aren’t even perceived as metaphors (“his argument was rock-solid”), and several studies have found that we process conventional metaphors just as quickly as literal statements. But is there really no difference in processing these common metaphors and literal statements? What about common ironic statements? Zohar Eviatar and Marcel Adam Just paid volunteers to submit to an fMRI scan while they read literal, metaphoric, or ironic statements.

In each case, a context was displayed (“Johnny went on a hike with his brother. Suddenly he saw a huge snake next to his foot”). Then the screen went bank for a few seconds. Then the test statement was made (in this case, literal: “He said, ‘I am so scared'”). After another break of a few seconds, the volunteers were asked a quick yes-or-no question to ensure they were paying attention (“was Johnny scared?”).

Here’s an example of a metaphor from the test:

In the morning John came to work early. He started to work right away at a fast pace.

His boss said, “John is a hurricane.”

And here’s an irony example:

George went to Betty’s birthday party. Only two people came.

He said, “It is really crowded here.”

Clearly the point of the study was not to examine our understanding of fine literature — these are the sorts of ironic and metaphoric statements we make every day.

So is there a difference in brain activity while processing irony, metaphor, and literal language? Take a look at this image:


All the images show where brain activity (measured by blood flow) is significantly higher on average while reading the key statement (literal, ironic, or metaphoric) than during rest. The top row shows the left hemisphere, where as you can see, much more is going on compared to right hemisphere. This, for the most part, represents the basic language-processing functions which have been observed by many researchers.

While it may appear that there are fewer differences in left-hemisphere activity compared to the right (in the bottom row), the researchers actually identified four regions in the left hemisphere which had significant differences in activity when different types of statements were being read. They also found two areas in the right hemisphere with similar activity differences.

Not only were these common metaphors and ironic statements processed differently from ordinary language, they were processed differently from each other. So, it seems, our semantic distinction between irony and metaphor actually corresponds to real differences in how the brain processes those statements.

I can already see the objection coming from my seventh-grad English teacher: What about similes? Actually, most psychologists don’t distinguish between similes (comparisons using “like” or “as”) and metaphors (direct, equivalence comparisons). Both were employed in this study.

Eviatar, Z., & Just., M.A. (2006). Brain correlates of discourse processing: An fMRI investigation of irony and conventional metaphor comprehension. Neurpsychologia, 44, 2348-2359.


  1. #1 Markk
    January 22, 2007

    This headline is ironic…or metaphorical… no I guess not, can’t tell. Sorry, anyway, the first thing I thought when I saw the headline was: Of course! How could human brains NOT tell? I mean we do have separate words that do mean different things so somehow our brains must be able to tell these things apart. It is more like – we can now SEE differences in brains dealing with metaphor and irony.

    By the way as a rant, in all these fMRI studies, I wish they would tell how many people are they doing them on to get a reasonable background and how much “significance” in the average increased blood flow. It always seems so dishonest that one brain with some area lit up is shown when really it is often many 10’s (100’s?) of brains with a lot of proccessing done to tease out signal that is the real thing. Plus it never shows what other areas are also active so one gets stupid stories saying we don’t use the reasoning part of the brain in politics or things like that when they have deliberately just not shown that area. Anyways, Rant off…

  2. #2 Dave Munger
    January 22, 2007

    In this particular study, the sample size was 16. I don’t have the report in front of me, but the figure illustrates the areas that are different to a particular degree of statistical significance — I don’t remember exactly what.

    I think in general your rant is well taken, but I do think in this case it’s interesting that two very similar phenomena are processed in different parts of the brain.

  3. #3 Tim
    January 22, 2007

    If we can distinguish between two things, they are processed differently by our brain. Simple fact.

    Did you really have an a priori hypothesis about what areas might be active or what that might mean? If not, this study adds nothing useful at all, since it does not address any cognitive theories — things can be processed exactly the same but it can occur in different brain areas, or they can be processed differently in the same area. All this stuy addresses is any hypotheses you had about BOLD or neurophysiological organization of processing, which I suspect are sparse.

    And I say this as a cognitive neuroscientist who does fMRI.

  4. #4 David Group
    January 23, 2007

    I suppose the next step would be to do this study on autistics.

  5. #5 Phronk
    January 23, 2007

    I’m no expert, but I always thought there was a difference between sarcasm and irony. As defined here, they seem to be the same thing. However, saying the opposite of what is meant seems more like sarcasm than irony to me.

    I thought that irony is more about expectation. It’s ironic if an article about proper spelling contains typos, because you wouldn’t expect it to. There is also another aspect to irony that’s hard to define, though. Not everything that’s unexpected is ironic.

    I guess these things are hard to define…I just wonder if the operational definitions adopted by these researchers are even close to the intuitive everday definitions we use. But as Alanis Morisette proved, irony is particularly tough to talk about (though it IS ironic that a song all about irony does not contain any genuine examples of irony…isn’t it?)

  6. #6 Dave Munger
    January 23, 2007

    According to my dictionary widget, sarcasm is the use of irony to mock or display contempt.

    Also, irony in a narrative is different from irony in speech. In a narrative, irony typically is when the opposite of what we expect occurs. In speech, irony is saying the opposite of what we mean.

New comments have been disabled.