The Third Thumb: Easy adaptation for enhanced manual dexterity

Third Thumb Cambridge University Study
Ever wished you had an extra thumb for that extra dexterity? Images courtesy Dani Clode

Adding an extra thumb to one hand can significantly enhance manual dexterity, but many might assume it would be difficult to learn to use. However, a recent study indicates that most people can master the Third Thumb in just one minute, showcasing its potential for widespread use and utility.

The Third Thumb was first introduced in 2017 by British designer Danielle Clode as her master’s graduate project at the Royal College of Art in London. The device features a 3D-printed articulated thumb that is strapped onto the user’s right hand, positioned opposite their natural thumb. It connects to a wrist-worn motor module via a cable, and this module wirelessly links to two pressure sensors placed under the user’s big toes. Pressure applied to the right sensor moves the thumb laterally, while pressure on the left sensor moves it towards the fingers. The intensity of toe pressure controls the thumb’s speed, and releasing pressure returns the thumb to its “home” position.

When neuroscientists at University College London saw the Third Thumb on the news, they reached out to Clode to incorporate the device into their research on body augmentation. A 2021 study involved 20 volunteers who had five days to learn to use the thumb, practicing for two to six hours daily. This study revealed significant changes in the brain’s sensorimotor cortex but did not provide extensive insight into the technology’s usability across a broader population.

The University of Cambridge addressed this gap with a new study based on data from the 2022 Royal Society Summer Science Exhibition. Over five days, 596 participants from diverse demographic backgrounds, aged between three and 96, were given one minute to familiarize themselves with the device. All but four participants could purposefully move the thumb after the brief training, with small children unable to exert enough toe pressure and some participants facing fit issues. Additionally, 583 participants could manipulate objects using the thumb.

Third Thumb Royal Society Summer Science Exhibition
Attendees at the Royal Society Summer Science Exhibition test out the innovative Third Thumb.

Participants were then asked to perform two specific tasks post-orientation. The first task involved using only the thumb to pick pegs from a pegboard and place them in a basket within 60 seconds, successfully completed by 333 participants. The second task required using the thumb alongside the hand to pick and place various foam objects of different shapes and sizes within a minute, completed by 246 participants.

Third Thumb Holding Bag
The Third Thumb enables you to perform intricate tasks with ease, offering capabilities beyond those of a single thumb.

Notably, the study found no performance differences between genders or between left- and right-handed users, despite the device being right-hand-only. There was also minimal performance variation between younger and older adults, though older participants generally showed a slight decline, potentially due to sensorimotor and cognitive skill deterioration or less familiarity with technology.

This study underscores the potential of the Third Thumb not only for enhancing the abilities of able-bodied users but also for assisting those with diminished manual dexterity. “Augmentation is about designing a new relationship with technology – creating something that extends beyond being merely a tool to becoming an extension of the body itself,” says Clode, now collaborating in the lab of Professor Tamar Makin at the University of Cambridge. She emphasizes the importance of inclusivity in the design stage of wearable technology, ensuring these devices are accessible and functional for a wide range of users.

Third Thumb Learning
Left-handed users found the right-hand-specific Third Thumb surprisingly easy to master.

As the Third Thumb continues to develop, its applications could expand further, offering significant benefits for various user groups. This study highlights the device’s immediate usability and the potential for broader adoption, paving the way for advancements in wearable technology and body augmentation.

Third Thumb Designer Dani Clode
Designer Dani Clode demonstrates the innovative Third Thumb, a device that enhances manual dexterity by adding an extra, fully functional thumb.

Source: University of Cambridge