Wednesday, 25 February 2026 Does everybody? Does anyone? Do they always? What inter- and intraindividual stability of cognitive effects can tell us about (numerical) cognition?

A seminar entitled Does everybody? Does anyone? Do they always? What inter- and intraindividual stability of cognitive effects can tell us about (numerical) cognition? will be held on 9 March at 11:00 am in the VP3 Lecture Room. The seminar will be delivered by Prof. Krzysztof Cipora.

Cognitive psychologists generalize a lot: not only from samples to the population, but also from group-level effects to believing that these effects are present and stable in all individuals. Such generalisations have important implications for theory building – most theories of cognitive / experimental psychology assume universality of observed phenomena. In this talk I will present work on individual prevalence of numerical cognition phenomena: the SNARC effect (various instances), the Numerical Distance Effect, the Size Effect, and the Unit-Decade Compatibility effect. Taken together, this work shows that even robust group-level effects can be driven by a minority of participants who reveal these effects above chance level.

The said effects differ with regards to individual prevalence and proportion of individuals revealing reliable reverse effects. Knowing whether an individual reveals a reliable effect or not based on results of a single session, one may wonder whether revealing a reliable effect is an individual characteristic, which is stable across time. We investigated this for the SNARC effect. In a subsequent study, participants performed the typical SNARC task for 30 days.

We observed massive intra-individual variation in SNARC and other effects that could be calculated from the parity judgment data. Taken together, these findings show that novel insights into experimental psychology can be obtained using differential psychology approach. Inter- and intra-individual stability may potentially be considered in theory building.

Prof. Cipora will take part in the Visiting Professorship programme within the framework of Transform4Europe (T4EU), an international initiative that brings leading scholars to partner universities to enrich teaching, research, and academic collaboration.

The programme goes beyond short-term mobility, supporting knowledge exchange, interdisciplinary cooperation, and joint engagement with key societal, digital, and environmental challenges across Europe.