It seems like fingers too can be deceived. A team of cognitive scientists has discovered a new perceptual illusion.
In the study, researchers at the Cluster of Excellence Cognitive Interaction Technology (CITEC) of Bielefeld University "outwit" human perception.
Test subjects placed their index finger in an apparatus and touched an object whose softness changed at random without the person noticing. While touching the object, the test subjects were under the illusion that it was the position of their finger that changed, not the softness of the object. The curious thing here was that the test subjects felt an "illusory" finger displacement, much larger in extent than the actual, "real" displacement.
Team leader Dr. Marc Ernst said "We now have a better understanding of how we can virtually convey the impression of whether an object feels soft or hard. In the future, this should help in developing a virtual sense of touch with which one can 'touch' things across distances, such as how a sweater or another product feels while shopping online."
"A fundamental question in this project is what role haptic stimuli play in perception," says Ernst. With the term 'haptic stimuli,' the cognitive scientist is referring to the sensations that arise from touch. A special feature of our finger pads is that they are fleshy, they can 'deform' by giving way when touching something. For instance, when a person touches a sponge, she feels its composition and consistency through the tactile sensors in her skin.
The key here is how much surface area of the object comes into contact with our skin. The greater the area of contact, the closer the object seems to be, and therefore, the more the finger appears to be bent. Why is this finding significant? "If we were not to know exactly how our body is positioned, we would not be able to grasp or catch, and therefore could not interact with objects or other people," explained Ernst.
The study appears in the scientific journal Current Biology.
