In a groundbreaking study, researchers at the University of Cambridge have demonstrated the remarkable ability of the public to quickly adapt to using a "third thumb"—a controllable, prosthetic extra thumb designed to enhance human motor capabilities. The findings, published in Science Robotics, highlight the importance of inclusive design in ensuring new technologies can work for everyone.

An emerging area of future technology, known as motor augmentation, involves the use of motorized wearable devices such as exoskeletons or extra robotic body parts to advance our motor capabilities beyond current biological limitations. While these devices could improve productivity for healthy individuals, they also hold tremendous potential for providing new ways for people with disabilities to interact with their environment.

Professor Tamar Makin from the Medical Research Council (MRC) Cognition and Brain Sciences Unit at the University of Cambridge emphasized the significance of inclusivity in innovation, stating, "Technology is changing our very definition of what it means to be human, with machines increasingly becoming a part of our everyday lives, and even our minds and bodies. To ensure everyone will have the opportunity to participate and benefit from these exciting advances, we need to explicitly integrate and measure inclusivity during the earliest possible stages of the research and development process."

The Third Thumb, developed by Dani Clode, a collaborator in Professor Makin's lab, is a robotic extra thumb aimed at increasing the wearer's range of movement, enhancing their grasping capability, and expanding the carrying capacity of the hand. Worn on the opposite side of the palm from the biological thumb, the Third Thumb is controlled by pressure sensors placed under each big toe or foot. Pressure from the right toe pulls the Thumb across the hand, while pressure from the left toe pulls it up toward the fingers, allowing for proportional control based on the applied pressure.

During the 2022 Royal Society Summer Science Exhibition, the team had the opportunity to test the Third Thumb on a diverse range of 596 participants, ranging in age from 3 to 96 years old and from various demographic backgrounds. Remarkably, only four participants were unable to use the device, either due to a poor fit or inability to control it with their feet.

Participants were given up to a minute to familiarize themselves with the device and were then asked to perform one of two tasks: picking up pegs from a pegboard with just the Third Thumb and placing them in a basket, or using the Third Thumb together with their biological hand to manipulate and move various foam objects.

The results were astonishing. Ninety-eight percent of participants were able to successfully manipulate objects using the Third Thumb during the first minute of use, with no significant differences in performance between genders or handedness. Older and younger adults had similar ability levels, though a decline in performance was observed with increasing age among older adults, potentially due to age-related sensorimotor and cognitive changes.

While younger children generally performed worse compared to older children and adults, the researchers noted that even older children aged 12-16 struggled more than young adults, highlighting the importance of considering different age groups in the design process.

Dani Clode emphasized the significance of inclusive design, stating, "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. Given the diversity of bodies, it's crucial that the design stage of wearable technology is as inclusive as possible."

Co-author Lucy Dowdall added, "If motor augmentation—and even broader human-machine interactions—are to be successful, they'll need to integrate seamlessly with the user's motor and cognitive abilities. We'll need to factor in different ages, genders, weight, lifestyles, disabilities—as well as people's cultural, financial backgrounds, and even likes or dislikes of technology. Physical testing of large and diverse groups of individuals is essential to achieve this goal."

The study underscores the importance of inclusive design considerations, as a lack of diversity in the development process has led to numerous technological failures, from speech recognition systems performing better with white voices to car safety features designed primarily for average male-sized dummies, putting women at higher risk in accidents.

As motor augmentation and human-machine interactions continue to evolve, the Cambridge researchers' work emphasizes the need for a concerted effort to ensure that these transformative technologies are accessible and functional for all, regardless of age, gender, or ability. By embracing inclusive design principles from the earliest stages, we can unlock the full potential of innovation to enhance the lives of everyone in society.