Primates communicate to influence others’ behavior. Communication signals evolved to enable us to share information, communicate our emotional state, change the emotional state of the receiver and therefore manipulate action. In humans, language is essential to our communication, especially when we are selecting leaders.

Since ancient Greek civilization, we have sought to identify what makes some people more effective and persuasive orators than others. Despite this, we still have a poor understanding of the relevant psychophysiology, which refers to the relationship between physical processes and psychological phenomena.

Previous studies have suggested that entrainment-inducing stimuli are important in successful oration. Entrainment is the phenomenon of a rhythmic pattern or signal causing another system to synchronize with it. For example, when people listen to music, they tap their feet or clap, falling in sync with the rhythm of the music.

Acoustic-prosodic entrainment, or the extent to which people match each other’s speech patterns, has been shown in some research to be predictive of conversational success between people. Researchers have observed patterns in sounds and rhythms, or perceptual repetitions, in well-known English poetry, which may suggest that regular, predictable patterns are appealing. Entrainment is also believed by some scholars to play a role in social bond formation. However, robust empirical evidence of the phenomenon is lacking.

To understand more about the effect of perceptual repetition on the success of oratory, Dr. Ceccherini-Nelli of the University of Alberta conducted a comparative study. He and his colleagues took the political speeches of successful leaders, such as Barack Obama, and compared them to the communication patterns of the mathematician and Nobel laureate John Nash, before and after the onset of schizophrenia. Schizophrenia was chosen because it is a mental illness characterized by poor social functioning, discordant emotions, impaired recognition and expression of emotions in spoken language, and impaired musical perception.

In their linguistic analysis, they found that Obama and John Nash (in a paper published in 1958, before the onset of psychosis) had the highest frequency of repetitions of dental consonant sounds, which are speech sounds produced by the tongue against the upper teeth. This was significantly higher than in a technical manual they analyzed, and in a ‘comic novel’ by a second subject with schizophrenia. Obama had the highest average number of consonant repetitions across lines, while the ‘comic novel’ had the lowest. In a subsequent paper by Nash (1966) the average number of consonant sound repetitions was lower and close to the ‘comic novel’.

Next, Dr. Ceccherini-Nelli and his colleagues wanted to explore why the patterns they had found might make leaders’ speeches more persuasive. They tested whether repeating sound patterns in speech or writing helped to keep listeners focused, using a test where people quickly decide if a string of letters is a real word or not. They hypothesized that repetitions found in Obama’s speech would result in better recognition than words from the comic novel. This would occur because of phonological priming, where reaction times and accuracy are improved by preceding the test word with some words that relate in terms of their sounds and patterns.

The study found that, on average, participants identified words and non-words with 94% accuracy for Obama’s speech and 92% for the schizophrenic subject’s comic novel. Reaction times were 52 msec faster for Obama’s speech compared with the comic novel. Both differences were statistically significant.

Secondly, Dr. Ceccherini-Nelli and his colleagues examined if the rhythm of the speech, turned into music without the words, could create emotional responses in listeners.

The researchers converted the speech into music using a method that analyzed the speech’s pitch and frequencies. Rather than using pre-existing methods that did not factor in consonant sounds, they created a new method to analyze the pitch of each phonetic symbol in Obama’s speech and the comic novel. Then, they matched these pitches to musical notes. In doing this, Dr. Ceccherini-Nelli and his colleagues aimed to preserve the emotional qualities of the speech, without providing any semantic information.

Finally, they played the resulting musical scores using a flute sound. Volunteers were asked to rate these pieces and two other songs. One song was a compilation of “annoying” music played using a flute. It was found and downloaded from You Tube, using the search keywords “annoying”, “disturbing” and other negative terms. The last song played to volunteers was the Bird Catcher’s aria from Mozart’s Magic Flute opera.

The study found that music made using Obama’s speech evoked feelings of nostalgia and peace, while the ‘comic novel’ music did not evoke high levels of joy in listeners. The “annoying” music was perceived as chaotic and tense. Mozart’s music predominantly evoked a feeling of joyful activation.

Mozart’s music had the highest overall emotional score, while the comic novel had the lowest, but the differences weren’t significant. However, there were significant differences in emotional responses across groups, particularly in power, tenderness, nostalgia, peacefulness, joy response, sadness, tension, and chaos. Obama’s music scored highest in nostalgia, had a peace response similar to Mozart’s, and the lowest tension. This matched the emotional context of Obama’s speech, which was on nuclear disarmament. The comic novel music scored highest in sadness, which didn’t match its context.

So, what does this all mean?

From the results of the first test on Obama’s speech, Dr. Ceccherini-Nelli and his colleagues suggest that his oration may be perceived as clearer and more memorable due to lexical access priming mechanisms, in which the retrieval of words and ideas are facilitated by specific patterns of speech. In their second test, they proved that Obama’s speech could elicit emotional responses in listeners that agree with the contextual meaning of the speech. On the contrary, the writing of a schizophrenic subject elicited emotional responses that were not consistent with the context. This provides indirect evidence of emotional entrainment, or synchronization, between Obama and his audience.

In this research, Dr. Ceccherini-Nelli and his colleagues provide robust evidence that political speeches have superior organized rhythmic and melodic patterns compared with other types of verbal or written communication. They provide possible explanations for why this might make them powerful, effective and persuasive. This suggests that humans, through the subconscious analysis of language, can select individuals with the cognitive skills needed to lead their social groups.