Rutgers-Newark Psychology Researchers Reveal Link Between Body And Action Perception

In the article, "Understanding Another's Expectation from Action:The Role of Peripheral Sensation," that will appear in the October 2005issue of Nature Neuroscience, Rutgers-Newark Psychology ProfessorGuenther Knoblich is among a group of researchers who contend thatindividuals use the human body's senses to understand others actionsand expectations. The researchers reached this conclusion by performingexperiments with two individuals suffering from the rare neurologicaldisorder of selective and complete haptic deafferentiation due tosensory neuronopathy. The participants are the only two knownindividuals in the world whose sense of touch and body movement wascompletely eradicated by the degenerative disease.

The individuals participated in tasks that tested theirability to gauge the weight of boxes which were lifted by otherindividuals and their ability to infer weight expectations of theobserved individuals. Their performance was compared against a controlgroup comprised of healthy individuals.

"In order for an individual to perform a motor activitysimulation, you need to know how it feels to perform the action,"Knoblich notes. "The two deafferented individuals do not feel theirbodies. They must see their bodies to perform the simplest actions,such as standing upright. We asked whether their lack of bodyperception would also affect their ability simulate others' actionswhile observing them."

The tasks involved individuals observing someone lifting a boxand attempting to determine and report the object's weight. In some ofthe instances, the individuals doing the lifting were correctlyinformed of the boxes weight. In other instances, investigators misledthe lifting person about the weight of the box. The patients andcontrol group viewed videos and afterwards either estimated the weightof the box or reported whether or not they thought that the personlifting the box was deceived beforehand about its weight.

"We observed that there was no difference in the responseswhen the two groups were asked to estimate the object's weight,"Knoblich explained. "However, when performing the expectation task andasked to determine whether or not the person lifting the object wasdeceived about its weight, the patients couldn't do it."

According to Knoblich, the patients were unable to accuratelyrespond to the expectation task because they could not perform a motorsimulation. However, they were fully able to process the simpleperceptual cues which indicate the weight of the object. Knoblich saidthese results go a long way toward establishing the view that thebody's senses are critical to a human's ability to understand theactions and expectations of others.

"It solidifies the new embodiment view that is becomingincreasingly popular in the cognitive and neurosciences," Knoblichnotes. "It is interesting that there seem to be parallel developmentsin science and art. While science questions the assumption that humancognition can be viewed as disembodied, computer-like informationprocessing, many contemporary visual artists and performers seem tomove away from abstraction to re-discover the human body as an objectof art."