Do we think with our hands?

Scientists have been trying to understand how people process and understand words.

Experts already know that humans recognise objects based on their relationship and interaction with their environment. For example, a cup is not an isolated object. It can be understood with the additional information that it is a container made of a certain material and is used for drinking. Only then can a person use it for good.

This is an issue AI scientists face when making robots.  They have to teach them symbol grounding which is the process through which symbols are mapped onto the real world. 

The question is: How do humans achieve symbol grounding?

A research team led by Professor Shogo Makioka at the Graduate School of Sustainable System Sciences, Osaka Metropolitan University,  decided to test embodied cognition.

Embodied cognition is when objects become meaningful because of their interaction with the body and environment.

A study was conducted by the team to see how brains respond to words that describe objects that are manipulated by hand. In one instance, they restrained the hands and in another, they left them free.

They measured brain activity through functional near-infrared spectroscopy (fNIRS). Two words were shown to each participant and they were asked to compare the sizes and report which one was larger.

Two words, like cup and broom, were shown. Both of these objects can be manipulated by hand.  In another instance, two words that described nonmanipulable objects, like lampost and building, were shown.

Researchers wanted to observe how each type of object was processed in the brain.

The fNIRS focused on the centres of the brain responsible for semantic processing, which is a process where we encode the meaning of words.

Scientists recorded the speed with which participants responded.

The findings showed that when the hands were restrained, the activity in the left brain was reduced in the case of hand-manipulable objects. Results reported in the journal Scientific Reports suggest that restraining hand movements affect how we process the meanings of objects.