Cognitive biases, communicative efficiency and propaganda

If an alien visited our planet now, it would be very surprised to learn that our species is called homo sapiens, or “wise human being”. Meaningless wars, wild conspiracy theories, the anti-vaccination movement – all that demonstrates that our species is not very wise, to say the least.

Are we poor thinkers? The Nobel-prize winning experiments conducted by Daniel Kahnemann and Amos Tversky suggest that logical thinking is indeed a challenge even for well-educated humans. For example, they seem to struggle with estimating probabilities. In one of the experiments, the participants were asked to read this text:

“Linda is 31 years old, single, outspoken and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.”

After that, the participants ranked statements about Linda according to their probability. The statements included the following:

  • “Linda is a bank teller.”
  • “Linda is active in the feminist movement.”
  • “Linda is a bank teller and is active in the feminist movement.”

The majority of the participants judged the third statement, “Linda is a bank teller and is active in the feminist movement” as more probable than “Linda is a bank teller”. But this makes no sense mathematically: The probability of a conjunction of two possible events (a bank teller AND a feminist activist) cannot be higher than the probability of one of these events (a bank teller). From this and other findings, Kahnemann and Tversky concluded that humans do not deal very well with probabilities and logic.

Some psychologists have questioned this interpretation, pointing out that the experiments contained semantic and pragmatic ambiguities. For example, Ralph Hertwig and Gerd Gigerenzer argued that the participants interpreted the word “probability” non-mathematically, based on semantic and pragmatic inferences from the linguistic cues provided in the text.

I agree with the sceptics. I think that the participants behaved in a way that usually saves costs in human interaction. In my book Communicative efficiency: Language Structure and Use, which has just been published by Cambridge University Press, I formulated three principles of efficient communication:

  1. The principle of positive correlation between benefits and costs. This means, for example, that you don’t mention things irrelevant for interaction.
  2. The principle of negative correlation between costs and accessibility (or expectedness, typicality, givenness…). In other words, you shouldn’t spend too much effort and time on self-evident or highly predictable information.
  3. The principle of maximization of accessibility at every point in communication, which means choosing the most accessible interpretation, among other things.

The participants’ responses can be explained by these principles. According to the first principle, if something is mentioned, it should be relevant in some way for communication. Otherwise, why waste effort? Since the text contains a lot of information about Linda’s political views, it should play some role in interaction. This principle is similar to Grice’s maxim of quantity: be as informative as you possibly can, and give as much information as is needed, and no more.

Fresh author copies from Cambridge University Press. Penguins play a prominent role in the book.

The other principles are also at work here. The principle of negative correlation between accessibility and costs suggests that highly accessible meanings are expressed by shorter forms. Stereotypical information is highly accessible, so a short expression can create an expectation of something typical. The logic is similar to Stephen Levinson’s I-heuristic, “What is simply described is stereotypically exemplified”. And the principle of maximization of accessibility tells the addressee to choose the most accessible interpretation, given the cues provided. A prototypical bank teller is probably not a feminist activist. This is why the statement “She is a bank teller” could be interpreted as “She is a bank teller not actively participating in the feminist movement”. In fact, when Don Dulany and Denis Hilton corrected for this inference in their experiments, the proportion of conjunction errors went down.

So, I don’t think that the participants were stupid. They tried to be efficient and expected the same from the experimenters. In the overwhelming majority of real-life situations, these expectations are justified. In fact, it would be very inefficient to revise these expectations in every communicative event.

The real problem, however, is that these expectations can be easily exploited by manipulators. For example, Putin justified his decision to invade Ukraine on February 24 by saying that Russia wanted to stop the “genocide” in Donbass.

We had to stop that atrocity, that genocide of the millions of people who live there and who pinned their hopes on Russia, on all of us.

V.Putin, 24.02.2022. Source:

In this sentence and in many others, the fact of “genocide” is presented as something already known, part of common ground. It is presupposed, rather than focused on. There is convincing psycho- and neurolinguistic evidence that we process presupposed information less deeply than information in focus. This is why we fall for semantic illusions, like “How many animals of each kind did Moses take on the arch?” Most people answer automatically “Two”, although they know perfectly well that it was Noah who built the arch. Since we have limited attentional resources, this processing strategy is efficient. It usually pays off to spend more effort on the new and relevant information and less on something we already know.

Although Putin presents “genocide” as common knowledge, it is true only in Kremlin’s distorted picture of the world. According to the OHCHR report, 3,107 civilians were killed as a result of the conflict on both sides from 14 April 2014 to 31 January 2022. The overwhelming majority were killed in the beginning of the conflict in 2014, with fewer and fewer casualties in the subsequent years. In 2021, 25 civilians were killed (see the report). Of course, even one person’s death is terrible, but it is very far from a genocide. Especially taking into account the fact that Putin’s war has killed at least 6,595 civilians since February 24, and it does not seem to bother him in the least.

So, our tendency to save effort, which has served our species pretty well for many millennia, can help manipulators to deceive us. There is only one solution: We must increase our processing efforts and grow an analytical muscle. Critical thinking is not en vogue, but it is vital for saving our democracy. Otherwise, the costs will be too high.

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