Abstract
How do we understand two-digit numbers such as 42? Models of multi-digit number comprehension differ widely. Some postulate that the decades and units digits are processed separately and possibly serially. Others hypothesize a holistic process which maps the entire 2-digit string onto a magnitude, represented as a position on a number line. In educated adults, the number line is thought to be linear, but the "number sense" hypothesis proposes that a logarithmic scale underlies our intuitions of number size, and that this compressive representation may still be dormant in the adult brain. We investigated these issues by asking adults to point to the location of two-digit numbers on a number line while their finger location was continuously monitored. Finger trajectories revealed a linear scale, yet with a transient logarithmic effect suggesting the activation of a compressive and holistic quantity representation. Units and decades digits were processed in parallel, without any difference in left-to-right vs. right-to-left readers. The late part of the trajectory was influenced by spatial reference points placed at the left end, middle, and right end of the line. Altogether, finger trajectory analysis provides a precise cognitive decomposition of the sequence of stages used in converting a number to a quantity and then a position.
Original language | English |
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Pages (from-to) | 512-529 |
Number of pages | 18 |
Journal | Cognition |
Volume | 129 |
Issue number | 3 |
DOIs | |
State | Published - Dec 2013 |
Keywords
- Holistic processing
- Mental number line
- Number representation
- Numerical estimation
- Two-digit numbers
All Science Journal Classification (ASJC) codes
- Experimental and Cognitive Psychology
- Language and Linguistics
- Developmental and Educational Psychology
- Linguistics and Language
- Cognitive Neuroscience