title: Adaptive Spontaneous Transitions between Two Mechanisms of Numerical Averaging.
abstract: We investigated the mechanism with which humans estimate numerical averages. Participants were presented with 4, 8 or 16 (two-digit) numbers, serially and rapidly (2 numerals/second) and were instructed to convey the sequence average. As predicted by a dual, but not a single-component account, we found a non-monotonic influence of set-size on accuracy. Moreover, we observed a marked decrease in RT as set-size increases and RT-accuracy tradeoff in the 4-, but not in the 16-number condition. These results indicate that in accordance with the normative directive, participants spontaneously employ analytic/sequential thinking in the 4-number condition and intuitive/holistic thinking in the 16-number condition. When the presentation rate is extreme (10 items/sec) we find that, while performance still remains high, the estimations are now based on intuitive processing. The results are accounted for by a computational model postulating population-coding underlying intuitive-averaging and working-memory-mediated symbolic procedures underlying analytical-averaging, with flexible allocation between the two.
authors.affiliation: School of Psychology, Tel-Aviv University.
authors.forename: Noam
authors.initials: N
authors.lastname: Brezis
authors.affiliation: 1] School of Psychology, Tel-Aviv University [2] The Cohn Institute for the History and Philosophy of Science and Ideas, Tel-Aviv University.
authors.forename: Zohar Z
authors.initials: ZZ
authors.lastname: Bronfman
authors.affiliation: 1] School of Psychology, Tel-Aviv University [2] Sagol School of Neuroscience, Tel-Aviv University.
authors.forename: Marius
authors.initials: M
authors.lastname: Usher
mesh_terms: D008962:Models, Theoretical