Human behavior is a mystery that fascinates many scientists. There has been much discussion about the role of probability in explaining how our minds work.
Probability is a mathematical framework designed to tell us how likely an event is to occur, and it works well in many everyday situations. For example, he defines the outcome of a coin toss as ½ – or 50% – because flipping heads or tails is equally likely.
However, research has shown that human behavior cannot be fully reflected by these traditional or “classical” laws of probability. Could it instead be explained by the workings of probability in the more mysterious world of quantum mechanics?
Mathematical probability is also a vital component of quantum mechanics, the branch of physics that explains how nature behaves at the scale of atoms or subatomic particles. However, as we will see, in the quantum world probabilities are governed by very different rules.
Discoveries over the past two decades have shed light on a crucial role of “quantumness” in human cognition, that is, how the human brain processes information to obtain knowledge or understanding. These findings also have potential implications for the development of artificial intelligence (AI).
Human ‘irrationality’
Nobel laureate Daniel Kahnemann and other cognitive scientists have studied what they describe as the “irrationality” of human behavior. Patterns of behavior are considered “irrational” when, from a mathematical perspective, they do not strictly follow the rules of classical probability theory.
For example, one study found that the majority of students who passed the final exam chose to go on vacation afterwards. Likewise, the majority of unsuccessful people want to go on vacation.
If a student does not know his or her outcome, classical probability predicts that he or she will choose vacation because that is the preferred option whether he or she passes or fails. However, in the experiment, the majority of students chose not to take a vacation unless they knew how to do it.
Intuitively, it is not difficult to understand that students may not want to go on holiday if they are constantly worrying about their exam results. However, since classical probability does not fully reflect behavior, it is defined as irrational. Many similar violations of the classical rules of probability have been observed in cognitive science.
Quantum brain?
In classical probability, when a series of questions are asked, the answers do not depend on the order in which the questions are asked. In contrast, in quantum physics the answer to a set of questions may depend largely on the order in which the questions are asked.
One example is measuring the spin of an electron in two different directions. If you measure the rotation first in the horizontal direction and then in the vertical direction, you will get a result.
Due to a well-known property of quantum mechanics, the results will often be different when the order is reversed. Simply measuring a property of a quantum system can affect what is measured (in this case the spin of an electron) and thus the outcome of subsequent experiments.
Order dependence can also be seen in human behavior. For example, in a study published 20 years ago about the effects of question order on participants’ answers, subjects were asked whether former US president Bill Clinton was honest. They were then asked if vice president Al Gore appeared honest.
When the questions were asked in this order, 50% and 60% of the participants, respectively, said they were honest. But when researchers asked participants first about Gore and then about Clinton, 68% and 60%, respectively, said they were honest.
On an everyday level, human behavior can be considered inconsistent because it often violates the rules of classical probability theory. But this behavior seems to fit the way probability works in quantum mechanics.
Such observations led cognitive scientist Jerome Busemeyer and many others to realize that quantum mechanics could more coherently explain human behavior in general.
Based on this surprising hypothesis, a new field of research called “quantum cognition” has emerged in the field of cognitive sciences.
How is it possible that thought processes are determined by quantum rules? Does our brain work like a quantum computer? No one knows the answers yet, but empirical data seems to strongly suggest that our thoughts obey quantum rules.
dynamic behavior
In parallel with these exciting developments, over the past two decades my colleagues and I have developed a framework for modeling or simulating the dynamics of people’s cognitive behavior as they digest “noisy” (i.e., imperfect) information from the outside world.
We have once again found that mathematical techniques developed to model the quantum world can be applied to modeling how the human brain processes noisy data.
These principles can be applied to other behaviors in biology, beyond the brain. Green plants, for example, have the extraordinary ability to extract chemical and other information from their environment, analyze it, and adapt to changes.
My rough guess, based on a recent experiment on common bean plants, suggests that they can process this external information more efficiently than the best computer we have today.
Efficiency in this context means that the facility can continuously reduce uncertainty about its external environment to the greatest extent possible under its conditions. This may involve, for example, easily detecting the direction the light is coming from so that the plant can grow in that direction. Efficient processing of information by an organism is also linked to energy conservation, which is important for its survival.
Similar rules may apply to the human brain, particularly regarding how our mood changes when we detect external signals. All this is important for the current course of technological development. If our behavior is best described by the workings of probability in quantum mechanics, then to accurately replicate human behavior in machines, AI systems probably need to follow quantum rules, not classical rules.
I call this idea artificial quantum intelligence (AQI). A lot of research is needed to develop practical applications from such an idea.
But an AQI could help us achieve the goal of AI systems that behave more like a real human.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Dorje C Brody receives funding from the Engineering and Physical Sciences Research Council (EP/X019926/1) and the John Templeton Foundation (62210). The views expressed in this publication are those of the author and do not necessarily reflect the views of the John Templeton Foundation.