Cognitive neuroscientists at Western University have proved that people have an unconscious ability to control and even manipulate objects without knowledge of size or space.
The findings, published this week in Psychological Science, show humans have an innate capacity for reaching out and grasping objects accurately from a cluttered environment — like a refrigerator or a desk — without properly perceiving the size of the intended objects.
The researchers from Western's world renowned Brain and Mind Institute (BMI) believe that brain mechanisms controlling hands and fingers access information about the size of objects out of the corner of the eye — even when people have no conscious experience with the size of the objects.
Conducting a series of experiments, investigators Juan Chen and Melvyn Goodale studied how well people can grasp an object in the far peripheral visual field (the edges of the visual field) when that object is surrounded by other objects. Specifically, Chen and Goodale asked participants to stare at a fixation point in front of them and to reach out and grasp the target object with their thumb and index finger or, in a corresponding trial, indicate the size of the object.
The research team found that even when participants had no idea what the size of the objects were, their fingers opened just the right amount to grasp the object properly without fumbling or dropping it.
“This finding is quite remarkable,” said Chen, a postdoctoral scholar in the Goodale Lab and the study's lead author. “It shows that people have the ability to perform actions towards objects even when the key feature controlling those actions is not accessible to the brain.”
According to the research team, this study not only provides critical insight into the functional organization of vision but also is also relevant for the development of more efficient control systems for robotics and human-machine interfaces, particularly for use in environments where the relevant features of the goal object have to be specified on the spot.
“We propose that there are two separate but interacting visual systems, one for controlling skilled actions and another for conscious perception,” said Goodale, BMI director and the study’s senior author. “This work provides new support for the theory — and sheds new light on the ‘division of labour’ in the human visual system.”