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Journalism of Courage
You can best determine the actual position of the Leaning Tower of Pisa when you are upright,according to a new study.
Newtons laws of motion predict that an object will fall when its centre-of-mass lies beyond its base of support. But how does your brain know whether the tower will fall or not?
The force of gravity is not sensed directly. It is the indirect effects of gravity that are detected, said Michael Barnett-Cowan,a Canadian postdoctoral neuroscientist and project leader for motion perception at the Max Planck Institute.
In the mid 19th century,Hermann Aubert tilted to one side and observed a vertical line as being tilted towards him.
Since Aubert we now know that the brain combines visual and vestibular information to determine gravitys direction relative to an internal representation of our body’s orientation,” said Barnett-Cowan.
Equipping observers with laptops,testing them upright and on their sides,and comparing the participants’ judgment of object stability and vertical line estimates,Barnett-Cowan team found evidence that our perception of the likelihood that an object will fall is relative to this biased perceived direction of gravity rather than gravity’s true direction.
“This is another fine example suggesting that in order for the brain to accurately represent objects in the world,it combines information from multiple sensory organs that individually do not provide an accurate representation of the physical world,” said Heinrich Bulthoff,Director of the Max Planck Institute for Biological Cybernetics.
“Here visual,vestibular and body sense cues are aligned and the brain can make use of this redundant information to maintain optimal perception and action,particularly when information from one sense is poor or lost,” he said.
These findings have important implications for existing theories of how humans perceive the physical stability of objects.
The study was published in the journal PLoS ONE.
