As material, the language and literature scholars and psychologists chose Obama’s last acceptance speech, which he gave in 2008, when he was still a U.S. Senator for Illinois and the Democratic hopeful. “Obama has a textbook speaking style,” says Christine Knoop, a scholar of literature at the Languages of Emotion cluster who was involved in the rhetorical analysis. That’s why his speeches are so well suited to interdisciplinary rhetorical study: They embody what has been taught as the theory of rhetoric for 2,500 years now.

For the experiment, the speech was shifted from the emotionally charged convention environment to a more sober, clinical location – a lab. The subjects had to go without the delivery, without Obama’s voice; instead, each person had to read the speech on paper. Doesn’t that significantly reduce a speech’s effectiveness – printed words taking the place of the speaker’s charisma?

“Yes, definitely,” says project manager, Oliver Lubrich, a professor of literature at the University of Bern, “but we’re looking for a very specific aspect that we want to study experimentally.” Obama’s speeches, he says, are “linguistically crafted down to the tiniest detail.” And it is those very “tiniest details” that the team is studying in the lab: the rhetorical devices. What is the effect of alliteration (repeating the same sound at the start of a word), anaphora (repeating words at the start of a sentence), or repeating the same conjunction (a polysyndeton)? “These kinds of formal microstructures have been used for centuries to make texts aesthetically appealing, emotionally moving, and persuasive in terms of content,” Lubrich explains. But how were the scholars able to find out empirically the extent to which these structures do in fact serve their purpose?

The scholars view their experiment as a pilot project, one that is supposed to explore how rhetoric can be studied in a lab setting in the first place. It is part of a larger series of experiments on “affective and aesthetic processes during reading.”

To measure the effect of Obama’s text without certain stylistic devices, those devices were systematically “deactivated.” The team prepared two additional versions of the speech with the same content, but with many fewer linguistic devices, so they were less dense in terms of rhetoric. The text of the 45-minute speech was also divided into eleven-line segments to allow for standardized questioning of the subjects. “In an experiment, we have to control as many factors as possible,” explains Ulrike Altmann, a neuroscientist who worked closely with the humanities scholars on the team during this process.

U.S. citizens living in Berlin were sought as test subjects and divided into three groups. One group was assigned to read the original speech on paper, while each of the two other groups was assigned to read one of the “de-rhetoricized” versions. The results were compared to measure the extent to which the effects of political language depend on the formal devices used. Participants were asked to assess the impact of the text on an ongoing basis while reading, which gave the scholars a curve tracing rhetorical impact. At the same time, subjects’ physical reactions were tested: Changes in skin conductance and minute movements of the facial muscles act as clues to possibly unconscious effects. The subjects were asked about their personalities and political views beforehand so that the scholars could later interpret the data with an eye to social and demographic factors as well.

Most of the participants found the experiment quite exciting, but many wondered why the Berlin-based scholars didn’t simply study the speeches made by German politicians, Altmann reports. They evidently could not imagine that the speeches given by Chancellor Angela Merkel are not fine-tuned like those of the U.S. President.

Important political speeches are events in their own right in the United States. People watch them on TV or on the Internet, they tweet about them, and the newspapers report on them. Speeches can drive politics; Obama himself is a prime example of that. In 2007, when his first candidacy looked doomed to fail after radical statements made by his former pastor appeared in the media, it was a speech that saved him. Obama’s “race speech,” on coexistence between black and white Americans, was a key factor in his nomination, Lubrich says – and it was so important because of its rhetorical quality. “It was hugely skillful how he set up antitheses during the speech, then bridged them with alliteration, suggesting through sound alone that he was able, with his person and his politics, to reconcile the contradictions inherent in the United States.”

The President’s speech before this year’s convention, by contrast, demonstrated much less dazzling command of rhetoric, Lubrich says. But even using less rhetorical craft could have been a conscious choice to show a sober, humble attitude. Obama might have done just that in response to accusations that he is all talk – an accusation that has dogged the art of oratory for 2,500 years.

Obama’s political opponents, the scholars say, try to use a less polished style to portray themselves as “straight talkers.” This is a form of anti-rhetoric, and one that, by the way, is also mirrored among conservative German politicians, such as Angela Merkel, or Helmut Kohl before her, as Lubrich points out. For experimental purposes, it is much easier to strip a good speech of its magic through specific rhetorical means than to polish a bad speech into a good one after the fact, Knoop says. The scholars tried that as part of the project, using a speech by former President George W. Bush that contains just half as many devices as a similar speech by Obama. In that regard, Obama’s presidency and his public speaking skills are a stroke of luck for interdisciplinary research on rhetoric.