SYDNEY: Humans can read and do arithmetic with no conscious awareness, according to new research that could lead to an updated scientific view of human consciousness.
The accepted view in cognitive science holds that consciousness is required to process language and arithmetic. However, researchers in Israel have now shown that non-conscious processing of simple semantic and mathematical expressions is possible.
“These results are exciting for a simple reason: all existing theories of human consciousness and the unconscious posit that these processes cannot occur non-consciously,” said study director Ran Hassin, from the Hebrew University of Jerusalem, Israel.
“What we found out is that people can read a few words and do arithmetic without ‘seeing’ the words or the equations. Hence, our discovery should lead to an updating of the scientific view of the human unconscious and consciousness – two of the most exciting challenges of the cognitive sciences in the 21st century,” he said.
“I ironed coffee”
Writing in the journal Proceedings of the National Academy of Sciences, the researchers documented laboratory experiments to test whether or not the brain can process language and arithmetic without conscious effort.
Target stimuli were presented to one eye whilst the other eye was distracted using a technique called Constant Flash Suppression (CFS), which involves presenting rapidly changing, colourful images to the eye. This dominates awareness and ensures that the target stimulus is not consciously seen for a few seconds. After this time the target will ‘pop’ into the study subject’s conscious awareness – called the popping time.
To test the non-conscious processing of language, the stimuli consisted of simple expressions. It was discovered that it took study participants considerably longer to become conscious of logical sentences (such as “I ironed clothes”), compared to illogical sentences (“I ironed coffee”). They also discovered that negative phrases (for example, “black eye”) ‘popped’ much faster than neutral or positive ones (“sand box”).
When the participants were not subjected to CFS, there was no difference in popping time between these phrases – suggesting that humans can read and process language non-consciously.
Correct answers responded to faster
In the second set of tests, the participants were exposed to CFS in one eye and an addition or subtraction equation in the other. The equation was then changed for a numerical value, which was either the answer to the equation or an unrelated number. The number following the equation was not suppressed by CFS, and the participants were instructed to read it aloud.
The researchers found that the number following the subtraction equation was responded to faster if it was the correct answer. However, there was no difference in the response times for addition equations – which the researchers reasoned to addition being easier. By shortening the time between the original equation and the number shown, the researchers again discovered that the correct answer was responded to faster.
“These results are intriguing and the use of CFS – a relatively new technique to the field – is particularly innovative and overcomes some problems with previous attempts to examine unconscious processing,” said Ben Newell, an associate professor in cognitive psychology at the University of New South Wales, Australia, who was not involved with the study.
“What it means to have a ‘self’”
Evidence that humans are able to non-consciously read multiple words has been sought for decades. However, it is only with the development of new techniques such as CFS that it has now been proven. Hassin and his colleagues are now working on projects “that may further change how we think of human consciousness and, more broadly, on what it means to have a self,” he said.
“If these results are proved to be reliable and replicable, they could have important implications for our understanding of the relationship between conscious and unconscious processes,” said Newell. “But it is a potentially big ‘if’,” he added, as previous work in this area has been challenged with alternative explanations being proposed.
“Before undertaking a radical reconceptualisation of what the unconscious can do, we need to be very confident that alternative explanations can be ruled out,” he said.
Language and arithmetic have previously been considered a conscious process, with consciousness long associated with capabilities that are largely unique to humans, the authors wrote in the paper.
“Language and math are two symbolic and abstract systems that other animals, to the best of our knowledge, do not have,” said Hassin. “So I don’t think it’ll turn out that dogs can do arithmetic. There’s data out there that shows that apes can understand abstract numbers (until nine). But can they do math? Interesting thought.”
Abstract of the paper, “Reading and doing arithmetic non-consciously”, published in PNAS.
The homepage of Ran Hassin