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hubie [soylentnews.org] writes:

Both tend to judge the co-occurrence of two events as more probable than one event alone [ucla.edu]:

Animals, like humans, appear to be troubled by a Linda problem.

The famous "Linda problem" was designed by psychologists to illustrate how people fall prey to what is known as the conjunction fallacy: the incorrect reasoning that if two events sometimes occur in conjunction, they are more likely to occur together than either event is to occur alone.

[...] In the 1980s, Nobel laureate Daniel Kahneman and his colleague Amos Tvesrky showed that in a variety of scenarios, humans tend to believe, irrationally, that the intersection of two events is more probable than a single event. They asked participants to answer a question based on the following scenario.

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.

Which is more probable?

1. Linda is a bank teller
2. Linda is a bank teller and is active in the feminist movement

The great majority of participants chose No. 2, although logically it is less probable than Linda being a bank teller alone. After all, No. 1 would not preclude Linda from also being an active feminist, but given the description of Linda, No. 2 may be easier for respondents to imagine.

The Linda problem and numerous similar studies seem to indicate that humans estimate the likelihood of an event using mental shortcuts, assessing how similar the event is to a model they already have in their minds. [...]

To determine whether the fallacy necessarily involves language and whether it is unique to humans, González engaged rats in a physical, not social, task. With psychology professor Aaron Blaisdell, she designed two experiments that required the rats to judge the likelihood of just a sound being present or both a light and sound being present in order to receive a food reward.

[...] The tendency to overestimate the likelihood that both sound and light were present, even if it meant no reward, demonstrates that, like humans, rats can show a conjunction fallacy, the authors said.

"Until now, researchers said this is unique to human cognition only because we haven't looked for it in animals," Blaisdell said. "If humans and other animals consider alternative states of the world during ambiguous situations to help decision-making, we might expect systematic biases such as the conjunction fallacy to show a broader distribution in the animal kingdom."

Journal Reference:
González, V.V., Sadeghi, S., Tran, L. et al. The conjunction fallacy in rats [open]. Psychon Bull Rev (2023). https://doi.org/10.3758/s13423-023-02251-z [doi.org]

Original Submission