People with prosthetic arms less affected by common illusion

January 22, 2018, University of Exeter
People with prosthetic arms less affected by common illusion
Most people wrongly judge smaller objects to be heavier than larger ones if they weigh the same. Credit: Lauren Jennings

People with prosthetic arms or hands do not experience the "size-weight illusion" as strongly as other people, new research shows.

The size-weight , which affects about 98 per cent of people, causes them to experience smaller objects as feeling heavier than larger objects of the same weight.

The study – led by the University of Exeter and the University of Strathclyde – compared the perception of people using their anatomical hands with that of amputees using limbs.

The researchers were surprised to find that the size-weight illusion was twice as strong in non-amputees lifting with their as it was in the prosthetic users.

"This unexpected finding suggests that using a prosthesis might fundamentally affect the way people perceive the world," said Dr. Gavin Buckingham of the Department of Sport and Health Sciences at the University of Exeter.

"People using a prosthetic hand perceive real weight differences just like everybody else, but the effect of the size-weight illusion is halved.

"The reasons for this are a little mysterious. It might be to do with the lack of sensory receptors in a prosthetic hand, or might depend on how the prosthetic hand is attached to the stump."

In a second experiment, the researchers tested how the illusion affected non-amputees who used a prosthetic hand simulator to lift objects.

The results were similar to those for amputees with – the effect of the size-weight illusion was halved.

Sarah Day, of the National Centre for Prosthetics and Orthotics in the Department of Biomedical Engineering at the University of Strathclyde, added: "Many amputees prefer not to use or hands, but the reasons for this are not well understood. Research like this might help us better understand why."

The research was carried out by academics at the University of Exeter, Liverpool Hope University, Manchester Metropolitan University, Heriot-Watt University and the University of Strathclyde.

The paper, published in the journal Psychonomic Bulletin and Review, is titled "The impact of using an upper-limb prosthesis on the perception of real and illusory weight differences."

Explore further: Interpreting brainwaves to give amputees a hand

More information: Gavin Buckingham et al. The impact of using an upper-limb prosthesis on the perception of real and illusory weight differences, Psychonomic Bulletin & Review (2018). DOI: 10.3758/s13423-017-1425-2

Related Stories

Interpreting brainwaves to give amputees a hand

September 13, 2017
Biomedical engineers at Wits are researching how brainwaves can be used to control a robotic prosthetic hand.

Weight of object not an issue when determining left or right-handedness

October 21, 2011
More than 90 per cent of the world’s population exhibit a strong preference for using their right hand, as opposed to their left, for grasping and lifting everything from car keys to coffee mugs. The cause of this near-global ...

Recommended for you

Hep C compounds alcoholism's effect on brain volume

March 16, 2018
(HealthDay)—Alcohol dependence has deleterious effects on frontal cortical volumes that are compounded by hepatitis C virus (HCV) infection and drug dependence, according to a study published online March 14 in JAMA Psychiatry.

Study with infants suggests language not necessary for reasoning ability

March 16, 2018
A team of researchers from Spain, Hungary and Poland has found via a study with infants that language may not be a necessity for the ability to reason. In their paper published in the journal Science, the group describes ...

Older adults' difficulties with focusing can be used to help put a face to a name

March 16, 2018
Everyone has experienced the awkward situation of meeting someone and then forgetting their name shortly after. Among older adults, this happens more often than not.

A little anger in negotiation pays

March 16, 2018
During negotiations, high-intensity anger elicits smaller concessions than moderate-intensity anger, according to a new study by management and business experts at Rice University and Northwestern University.

Study casts doubt on ketamine nasal sprays for depression

March 16, 2018
Researchers from the Black Dog Institute and UNSW Sydney have questioned the efficacy and safety of intranasal ketamine for depression, with their pilot trial stopped early due to poor side effects in patients.

Research reveals brain mechanism involved in language learning

March 15, 2018
Learning a new language may be more of a science than an art, a University of Sussex study finds.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.