A new mind-reading device is capable of decoding words that people are thinking but not vocalising. 

A recent study demonstrated the device's ability to decode the internal speech of two participants with quadriplegia, who had microelectrodes implanted in their brains. 

When prompted by either spoken sound or written text, the participants thought of specific words like 'spoon', 'python', and 'battlefield'. 

Subsequently, they were asked to vocalise these thoughts, allowing researchers to compare spoken against internally vocalised words.

In one remarkable instance, the device achieved an accuracy rate of 79 per cent in decoding the internal speech of one participant.

However, the results varied significantly with the second participant, where the accuracy dropped to just 23 per cent. 

Still, the work represents a proof-of-concept for a high-performance internal speech brain-machine interface.

The research identified the supramarginal gyrus as a promising brain region for implanting electrodes to facilitate this form of communication.

The device operates by capturing brain activity during 'inner speech' - words thought internally without vocalisation - and translating these thoughts into language. 

Although the technology is still in its early stages, the potential benefits for those with severe communication limitations are profound.

The study also explored the potential for different mental strategies, such as imagining the sound of a word or visualising it as written text, to enhance the effectiveness of the decoding process. 

Despite the varying degrees of success in accuracy, the researchers remain optimistic about refining the technology.

Further testing with more participants and a wider range of words is needed to improve the functionality and reliability of the device. 

The ultimate goal is to develop a tool that can restore the ability to communicate for people affected by severe speech impairments, significantly improving their quality of life.