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Free versus anchored numerical estimation: A unified approach
John E Opfer1, Clarissa A Thompson2, Dan Kim1
1The Ohio State University, 245 Psychology Building, Columbus, OH 43210, USA.
Children's number estimation is better explained by logarithmic models, especially without anchors. Anchors can cause estimates to appear better fit by cyclic power functions, suggesting a mixed model is most accurate.
Area of Science:
- Cognitive Psychology
- Developmental Psychology
- Mathematics Education
Background:
- Children's number-line estimation is debated, with conflicting data supporting logarithmic and cyclic power models.
- Methodological differences in studies may explain these discrepant findings on numerical representation.
- Previous research has not fully explored the impact of anchoring and sampling on estimation models.
Purpose of the Study:
- To investigate whether methodological factors, specifically anchoring and sampling, influence the descriptive adequacy of logarithmic versus cyclic power models of children's number-line estimation.
- To determine the conditions under which logarithmic and cyclic power functions best describe children's numerical estimates.
- To propose a more comprehensive model for children's number estimation.
Main Methods:
- A 2x2 between-subjects design was employed, crossing anchoring (free vs. anchored) and sampling (over-sampling vs. even-sampling).
- Ninety-six children participated and were assigned to one of the four experimental conditions.
- Estimation data from each condition were analyzed to determine the best fit for logarithmic and cyclic power functions.
Main Results:
- In three conditions (free/over-sampling, free/even-sampling, anchored/over-sampling), estimates were predominantly better fit by a logarithmic function.
- In the anchored/even-sampling condition, estimates were better fit by a cyclic power function, indicating an effect of anchors.
- Logarithmically-compressed numerical estimates were found to be independent of sampling methods.
Conclusions:
- The fit of cyclic power functions to children's estimates appears to be an artifact of anchoring procedures.
- Logarithmic compression is a robust feature of numerical estimation, unaffected by sampling strategies.
- A mixed log/linear model is proposed as a versatile framework for understanding both free and anchored numerical estimation in children.
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