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ERIC Number: EJ859184
Record Type: Journal
Publication Date: 2009-Oct
Pages: 13
Abstractor: As Provided
Reference Count: 0
ISSN: ISSN-0010-0277
Number Estimation Relies on a Set of Segmented Objects
Franconeri, S. L.; Bemis, D. K.; Alvarez, G. A.
Cognition, v113 n1 p1-13 Oct 2009
How do we estimate the number of objects in a set? Two types of visual representations might underlie this ability--an unsegmented visual image or a segmented collection of discrete objects. We manipulated whether individual objects were isolated from each other or grouped into pairs by irrelevant lines. If number estimation operates over an unsegmented image, then this manipulation should not affect estimates. But if number estimation relies on a segmented image, then grouping pairs of objects into single units should lead to lower estimates. In Experiment 1 participants underestimated the number of grouped objects, relative to disconnected objects in which the connecting lines were "broken". Experiment 2 presents evidence that this segmentation process occurred broadly across the entire set of objects. In Experiment 3, a staircase procedure provides a quantitative measure of the underestimation effect. Experiment 4 shows that the strength of the grouping effect was equally strong for a single thin line, and the effect can be eliminated by a small break in the line. These results provide direct evidence that number estimation relies on a segmented input. (Contains 7 figures.)
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A