A new study published in Psychophysiology has found that silently speaking to oneself in an emotional way – whether positively or negatively – can cause an increase in heart rate, even in the absence of physical movement.
For decades, psychologists have known that inner speech, which is the silent dialogue individuals have with themselves, is a common cognitive activity. Inner dialogue plays a role in regulating attention, motivation and emotion. However, limited research had been conducted on whether this internal voice could directly affect our body’s physiology.
Led by Mikkel Wallentin, researchers from Aarhus University in Denmark set out to explore this connection and investigate how emotional inner speech could influence heart rate compared to non-emotional speech, as well as the outcomes of positive compared to negative speech.
The research team conducted two experiments involving a total of 90 participants aged 18-75 years. Each person lay on a bed, wore heart rate monitors, and was asked to engage in one of three types of inner speech: positive self-encouragement, negative self-criticism, or neutral counting of numbers. Heart rate was continuously monitored and motion tracking ensured that any changes in heart rate were not attributable to physical movement.
In the first experiment, each trial lasted three minutes. In the second, the researchers shortened and varied the trial lengths to make the timing less predictable. Across both studies, the researchers observed that emotional inner speech – regardless of whether it was positive or negative – resulted in a statistically significant increase in heart rate compared to the neutral counting condition. However, no significant difference was found between the effects of positive and negative inner speech.
The heart rate increase typically began about 10 seconds after the start of the inner speech and tapered off over time. The researchers also ruled out other possible explanations, such as subtle body movements or changes in breathing. Even after filtering out these effects, the link between emotional inner speech and heart rate remained.
Interestingly, the study found no connection between these heart rate changes and participants’ scores on depression or rumination surveys. Most participants reported that they regularly talked to themselves and found the task easy to perform.
While the findings are compelling, the researchers caution that the effects were modest – less than one beat per minute on average – and may not reflect what happens in everyday life when people are walking, talking, or dealing with real emotional stress. Additionally, the study relied on participants to follow instructions about what kind of inner speech to use, without direct verification.
The study, “Heart Talk: Emotional Inner Speech Increases Heart Rate,” was authored by Mikkel Wallentin, Line Kruse, Xinyi Yan, Paula Samide, Anja Feibel Meerwald, David Trøst Fjendbo, and Johanne S. K. Nedergaard.
