Your best argument may lose its edge if listeners struggle to keep up with how quickly you deliver it.
Speaking at a lively pace can make a strong argument more convincing, but rushing can weaken its impact.
Very fast speech makes it harder for listeners to weigh up what they hear, reducing the advantage that good reasons have over weak ones.
The findings suggest that persuading someone depends partly on giving them enough opportunity to think.
When faster speech helps
The conclusions come from six experiments involving almost 4,000 people who listened to persuasive messages delivered at different speeds.
Across the experiments, increasing the pace from very slow speech initially improved impressions of the speaker’s confidence and encouraged closer consideration of the message.
However, these benefits eventually weakened or reversed as the delivery became faster.
This helps explain why simply telling someone to speak more quickly is incomplete advice.
A faster delivery can make an argument easier to engage with until the listener begins struggling to keep up.
Crucially, the consequences depend on whether the reasons being offered stand up to scrutiny.
Testing strong and weak arguments
In the two main experiments, listeners heard a proposal that would allow university students to pay lower tuition fees in exchange for working part-time.
Some heard strong arguments emphasising benefits such as smaller classes and better services.
Others heard weak arguments that included reduced leisure time and superficial improvements to the campus.
The recordings were digitally altered to change speaking speed while keeping other vocal features, such as pitch and intonation, unchanged.
Participants then rated their support for the proposal, with some also recording the thoughts that had occurred to them while listening.
The combined results showed that strong arguments gained an increasing advantage over weak ones as speech became faster, but lost some of that advantage at higher speeds.
In other words, delivery affected how effectively listeners distinguished a convincing case from an unconvincing one.
Why rushing backfires
A central part of persuasion is how carefully people consider the reasons they are given.
When listeners examine a message closely, they have more opportunity to recognise its strengths, spot its weaknesses and form their own reactions.
This benefits a strong argument, while exposing the shortcomings of a weak one.
Very fast delivery can interfere with that process, making the merits of the message less influential.
The analyses suggested that changes in how easily listeners felt they could follow the reasoning helped explain this pattern.
Although speaking speed also affected how confident the speaker sounded, confidence alone did not adequately explain the overall pattern.
One possible reason very slow speech is less effective is that it makes sustaining attention more demanding, while excessively fast speech leaves too little time to absorb the content.
No single ideal speaking speed
The experiments tested seven speaking speeds, ranging from 113 to 218 words per minute, but did not establish one ideal pace.
The most effective delivery is likely to depend on factors including the complexity of the message, the audience and the presence of distractions.
The findings also concern recorded persuasive messages, so they do not establish a universal rule for every conversation or public speech.
For someone presenting a strong case, the findings suggest keeping the delivery lively while giving listeners time to follow the reasoning.
Rushing may reduce the very scrutiny that would otherwise make a good argument convincing.
Related
The study was published in the Journal of Nonverbal Behavior (Guyer et al., 2025).
