Individuals tend to have a preferred distance at which they are able to judge depth accurately, a new study found. They overestimate depth when objects are closer and underestimate depth when objects are farther away.
In the research on depth perception, the research team, coordinated by Fulvio Domini, professor of cognitive linguistic and psychological sciences at Brown University and senior scientist collaborator at the Istituto Italiano di Tecnologia (IIT) in Italy, has shown that they could manipulate the distance at which adults accurately perceived depth, both through sight and touch, by tricking them into thinking they had a longer reach than they really do.
"When children start touching and playing with things, they don't just do it at any distance. They do it at a small range of distances," Domini said. "Our thought is maybe what the brain does is figure out a metric at that distance and the rest is all heuristic."
That optimal distance where people are most accurate, it turns out, depends on their mind's perception of arm length.
In experiments conducted at IIT with 41 volunteers, those they "trained" to think their arms were reaching farther than they really were subconsciously accepted that fiction and shifted the distance at which they best judge depth farther away.
They also had a finer ability to discriminate between two separate tactile stimuli, in that they could perceive them as distinct with less distance between them than before.
The findings of a role for arm length may help to explain depth perception and the limits of its accuracy, Domini said. In addition, the finding that depth perception can be predictably manipulated by changing perceived arm length could also matter to designers of robotic proxies, exoskeletons, and robotic surgery.
The researchers concluded saying that even in adulthood sensory systems are not fixed structures with immutable functions, they have instead found strong sensory plasticity that can be evoked within minutes in adults.
The study was published in the journal of Neuroscience.