The mind uses syntax to interpret actions

WASHINGTON - Most people are familiar with the concept that sentences have syntax or structure. A verb, a subject, and an object come together in predictable patterns. But apparently actions have syntax too!

When we watch someone else do something, we assemble their actions to mean something, say researchers.

“There are oceans and oceans of work on how we understand languages and how we interpret the things other people say,” says Matthew Botvinick of Princeton University, US, who co-wrote the paper with Kachina Allen, Steven Ibara, Amy Seymour and Natalia Cordova.

They thought the same principle might be applied to understanding actions, reports the journal Psychological Science.

For example, if you see someone buy a ticket, give it to the attendant, and ride on the carousel, you understand that exchanging money for a piece of paper gave him the right to get on the round thing and go around in circles, says a Princeton release.

Botvinick and colleagues focused on action sequences that followed two contrasting kinds of syntax - a linear syntax, in which action A (buying a ticket) leads to action B (giving the ticket to the attendant), which leads to outcome C (riding the carousel), and another syntax in which actions A and B both independently lead to outcome C.

They were testing whether the difference in structure affected the way that people read the actions.

The experiments were based on studies suggesting that people read a sentence faster if it comes after a sentence with the same grammatical form.

Indeed, people were able to read a sentence more quickly if it followed a set of actions arranged the same way than if it followed a sentence of the other type.

This indicates that readers’ minds had some kind of abstract representation of the ways goals and actions relate, says Botvinick.

“It’s the underlying knowledge structure that kind of glues actions together. Otherwise, you could watch somebody do something and say it’s just a random sequence of actions.”

In the carousel example, a Martian (someone from Mars) might not understand why John exchanges paper for another piece of paper, why he gives the paper to the other man, why he goes around and around in circles, and what relationship there is between these actions.