Scientists Model Words as Entangled Quantum States in our Minds

When you hear the word “planet,” do you automatically think of the word’s literal definition, or of other words, such as “Earth,” “space,” “Mars,” etc.? Especially when used in sentences, words tend to conjure up similar words automatically. Further, human beings’ ability to draw associations and inferences between words may explain why we’re generally able to communicate complex ideas with each other quite clearly using a limited number of words.

Research has shown that words are stored in our memories not as isolated entities but as part of a network of related words. This explains why seeing or hearing a word activates words related to it through prior experiences. In trying to understand these connections, scientists visualize a map of links among words called the mental lexicon that shows how words in a vocabulary are interconnected through other words.

However, it’s not clear just how this word association network works. For instance, does word association spread like a wave through a fixed network, weakening with conceptual distance, as suggested by the “Spreading Activation” model? Or does a word activate every other associated word simultaneously, as suggested in a model called “Spooky Activation at a Distance”?

Although these two explanations appear to be mutually exclusive, a recent study reveals a connection between the explanations by making one novel assumption: that words can become entangled in the human mental lexicon. In the study, researchers from the Queensland University of Technology (QUT) in Australia and the University of South Florida in the US have investigated the quantum nature of word associations and presented a simplified quantum model of a mental lexicon.

Classical vs. Quantum Correlations

The researchers begin by explaining the difference between classical correlations (in the Spreading Activation model) and quantum correlations (in the Spooky Activation at a Distance model). Specifically, no pre-existing elements or hidden variables exist in quantum correlations as they do in classical correlations. For example, a classical correlation would be a scenario in which someone writes the same number on two pieces of paper, and sends them to two distant ends of the Universe. When received, both papers have the same number, but this correlation is due to a pre-existing action.

On the other hand, the quantum analogue of this scenario is much stranger. At one end of the Universe, someone writes a number on a blank piece of paper. At the other end of the Universe, another individual discovers that the same number is written on another piece of paper. Called quantum entanglement, this scenario doesn’t occur in everyday life, but it has been observed at the quantum scale and is referred to as “non-locality.”