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Moses illusions, fast and slow
Jérémie Beucler1, Aikaterini Voudouri1, Wim De Neys1
1Laboratoire de Psychologie du Developpement et de l'Education de l'Enfant, Unite Mixte de Recherche 8240, Centre National de la Recherche Scientifique, Universite Paris Cite.
Abstract:
When asked "How many animals of each kind did Moses take on the Ark?" most people answer "Two," failing to notice that it was Noah, and not Moses, who took the animals in the Ark. "Fast-and-slow" dual process accounts of such semantic illusions posit that incorrect responders are not sensitive to their error and that overcoming the illusion requires deliberate correction of an intuitive erroneous answer. We present three experiments that force us to revise this dual process view. We used a two-response paradigm in which participants had to give their first, initial answer under cognitive load and time pressure. Next, participants could take all the time they wanted to deliberate and select a final answer. This enabled us to identify the intuitively generated response that preceded the final response given after deliberation. Results show that participants do not necessarily need to deliberate to avoid the illusion and that incorrect respondents consistently display error sensitivity (as reflected in decreased confidence), even when deliberation is minimized. Both reasoning performance and error sensitivity in the initial, intuitive stage tended to be driven by the semantic relatedness between the anomalous word (e.g., "Moses") and the undistorted word (e.g., "Noah"). We show how this leads to a revised model where the response to semantic illusions depends on the interplay of both incorrect and correct intuitions. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Insights
Most people incorrectly answer "Moses" took animals on the Ark. Revised dual-process models show that semantic illusions, like the Moses Ark illusion, involve both correct and incorrect intuitions, even with minimal deliberation.
Area of Science:
- Cognitive Psychology
- Psycholinguistics
- Human Cognition
Background:
- Semantic illusions, such as the 'Moses Ark illusion,' are common errors where individuals misattribute details (e.g., Moses instead of Noah).
- Traditional dual-process theories suggest these errors stem from an intuitive, fast response that requires slow, deliberate correction.
- These theories posit that individuals are insensitive to their errors unless they engage in effortful deliberation.
Purpose of the Study:
- To investigate the cognitive processes underlying semantic illusions and challenge existing dual-process models.
- To determine if error sensitivity and intuitive responses occur even when deliberation is minimized.
- To explore the role of semantic relatedness in the generation and resolution of semantic illusions.
Main Methods:
- A two-response paradigm was employed, requiring participants to provide an initial answer under cognitive load and time pressure, followed by a final, deliberated answer.
- This method allowed for the isolation of the intuitive response preceding the final judgment.
- Experiments manipulated semantic relatedness between incorrect and correct elements within the illusion.
Main Results:
- Participants did not always require extensive deliberation to avoid semantic illusions; error sensitivity was evident even with minimal deliberation.
- Incorrect responders consistently demonstrated error sensitivity, indicated by reduced confidence, even in initial, intuitive responses.
- Both intuitive reasoning performance and error sensitivity were influenced by the semantic relatedness between the anomalous word (e.g., 'Moses') and the correct word (e.g., 'Noah').
Conclusions:
- Existing dual-process models need revision, as semantic illusions are not solely driven by a lack of error sensitivity in intuitive responses.
- A revised model is proposed where responses to semantic illusions result from an interplay between both incorrect and correct intuitions.
- Semantic relatedness plays a crucial role in the initial intuitive processing and subsequent error detection in semantic illusions.
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