Speed limits and sophisticated shortcuts of human conversations

Humans may be better listeners than we give ourselves credit for. Not that we’re always absorbing the deeper meaning of what we hear, or being truly engrossed by the details of our coworker’s weekend, but the sheer speed that we can formulate responses to what’s being said is impressive. In casual conversation, the average pause between one person’s statement and their partner’s response can be as small as 200 milliseconds, the minimum time it takes for us to respond to even a simple stimulus like a starter’s pistol in a race. The fact that we can intelligibly respond to a full sentence in that time demonstrates just how specialized our brains are when it comes to language and communication.

Timing our talking

Not every language sounds the same, of course. There are different grammar structures, etiquette, and pronunciation that adds an immense amount of variation to the sound of each conversation. However, timing the intervals in recorded conversations around the world allowed researchers to move beyond anecdotal assumptions about how each language sounds, and revealed that all humans speak in an amazingly consistent pattern. On average, everyone in a two-way conversation will speak for around 2 seconds and then pause, waiting the aforementioned 200 milliseconds before receiving a response. While there were some outliers, like a 470 millisecond gap in a Dutch conversation or a 7 millisecond gap in Japanese, by and large all people’s pauses required that their brain was working at top speed, and possibly taking some shortcuts, to answer that quickly.

With our brains needing 200 milliseconds to recognize a sound, and possibly another 600 to retrieve even a single word from memory, it’s clear that we’re not waiting until it’s our turn in a conversation to start thinking of a response. To eliminate a larger gap in the conversation we’re probably starting to formulate our response as soon as our partner starts to speak. This doesn’t mean that we’re ignoring their statements, just carrying on in some sort of monologue with ourselves. Instead, we’re it’s thought that we’re making use of a range of cues as we listen such as word choice, emotion, body language and pitch. In the end, it’s actually a lot more work, as we’re relying on a larger range of data from our partner while simultaneously building and adjusting a new idea. Even changes to the usual 200 millisecond gap between responses can be a clue, as a longer or shorter pause can feel like you’re being cut off, or that there’s a purposely leading delay, begging for more information before someone can answer.

Patterns among primates

Between the degree of sophistication and near-universal timing of our speech, researchers have more reasons to believe that conversations are wired into us. While other primates aren’t known to have our vocalizations, they do seem to converse in similar patterns. Lemurs speak slower, but do establish consistent timing when howling to each other. Chimpanzees have been observed using similar rules in the timing of their hand gestures, indicating that this rhythm may run deeper than speech itself.

Source: The Incredible Thing We Do During Conversations by Ed Yong, The Atlantic