Israeli Scientists Closing in on the Mystery of the Human Unconscious

So how do we know that the bench didn't eat the zebra? And why can our unconscious do simple sums, when we can't even understand the problems?

Dan Even
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Dan Even

Researchers from the Hebrew University of Jerusalem reported this week that they have found that the unconscious part of the human brain is capable of carrying out activities requiring complex, rule-based thinking, including reading comprehension and solving arithmetic problems. The findings contradict existing scientific theories propounding that activities of that kind require consciousness, and they open a window to future studies that will enable the use of the power of the unconscious to discover information hidden in it.

The study was led by Prof. Ran Hassin, head of the university’s Department of Cognitive Sciences, and included over 270 students who were asked to perform 13 tasks in front of a computer screen, while wearing a device that separated the eyes’ lines of sight. The researchers screened different stimuli for each eye: The subject’s right eye was exposed to rapidly flashing images – colors and shapes that change at a rate of 10 times a minute, and that eye soon became the one that dominated the subject's consciousness.

The left eye was exposed to short phrases and arithmetic problems, which remained on the screen longer and were directed at the unconscious. At first some of the subjects were shown phrases that were not semantically logical, such as “The bench ate the zebra,” along with logical sentences such as “The lion ate the zebra.” They also were exposed to negative and neutral word pairs such as “concentration camp” and “ironed shirt.” The subjects were asked to press a key on the computer when they became aware of the phrase. The negative and semantically illogical phrases penetrate the consciousness more quickly, the findings showed.

Later some of the subjects underwent an experiment in solving arithmetic problems unconsciously: First simple arithmetic exercises were presented to the left eye, while dominant stimuli were presented to the right eye. Later both eyes were shown a number, and the subject had to pronounce the number. The researchers noticed that the subjects pronounced the number more quickly if it presented a solution to the arithmetic problem preceding it. “The finding indicates that the subject solved the exercise unconsciously,” says Hassin.

The study indicates the ability of human beings to perform rule-based operations with abstract symbols, such as words and numerals, unconsciously. Hassin says that scientific theories currently claim that it is impossible to read sentences or solve math problems without understanding them consciously, but those theories were based on experiments that did not give the unconscious enough time to work.

In previous studies the subjects were shown sentences within a large number of stimuli. “The new technique we used, presenting different stimuli to each eye, enabled the subjects to expose the unconscious to stimuli for two seconds, enough time to enable it to process them,” Hassin says.

Using the findings, the researchers hope to continue to examine the power of the unconscious and will soon be conducting a new study to examine whether it is also possible to ask the unconscious questions and to receive answers to them. Today we know that the unconscious is capable of far more than was once thought, says Hassin.

“Therefore, current theories of the unconscious processes and human consciousness need to be revised. These revisions would bring us closer to solving one of the biggest scientific mysteries of the 21st century: What are the functions of human consciousness?” he concludes.

Also participating in the study were students Asael Sklar, Uriel Goldstein, Nir Levy and Roi Mandel, with the assistance of Dr. Anat Maril of the psychology department. The conclusions were recently published by PNAS, the Proceedings of the National Academy of Sciences in the United States.

The cognition experiment at Hebrew University.Credit: Emil Salman