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Dissertation
The role of numerical and nonnumerical magnitudes in discriminative behavior: a comparative study
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2025
DOI: 10.25820/etd.007874
Abstract
Humans and nonhuman animals can quickly identify the number of items in a set, which is vital for adaptation and survival as it enhances the organisms’ ability to collect food, navigate their environment, and assess social interactions, among other situations. This ability relies on nonsymbolic representations of number, which do not require language or symbolic representations of number. In nature, the number of items in a set is correlated with nonnumerical magnitudes like the total area, volume, or density of the set, among others. This means that it may be possible to solve approximate numerical discriminations by relying on differences on nonnumerical magnitudes among the sets rather than using numerical information. Prominent theories of numerical processing differ on the importance that nonnumerical magnitudes have in numerical discrimination responses in humans and nonhuman animals. This dissertation assessed the role that numerical and nonnumerical magnitudes have on discrimination responses made by pigeons and humans. In a series of experiments both species were trained and tested in identical two-alternative forced-choice discrimination tasks that manipulated the numerical and nonnumerical magnitudes of the training stimuli. Results demonstrate that the extent to which both species’ discrimination responses rely on numerical and nonnumerical magnitudes is flexible and depends on the relative amount of information each stimulus dimension provides in any given task. Moreover, both species can identify and adapt to changes in tasks requirements, prioritizing their use of either numerical or nonnumerical information to maximize choice accuracy.
Details
- Title: Subtitle
- The role of numerical and nonnumerical magnitudes in discriminative behavior: a comparative study
- Creators
- Francisca Rocio Diaz Riquelme
- Contributors
- Edward A. Wasserman (Advisor)Cathleen Moore (Committee Member)J. Toby Mordkoff (Committee Member)John H. Freeman (Committee Member)Bob McMurray (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Psychology
- Date degree season
- Spring 2025
- DOI
- 10.25820/etd.007874
- Publisher
- University of Iowa
- Number of pages
- xi, 170 pages
- Copyright
- Copyright 2025 Francisca Rocio Diaz Riquelme
- Language
- English
- Date submitted
- 04/29/2025
- Description illustrations
- Illustrations, tables, graphs, charts
- Description bibliographic
- Includes bibliographical references (pages 131-143).
- Public Abstract (ETD)
If given the choice between two dishes with different amounts of grapes, both people and animals can quickly identify and choose the more abundant dish. This decision could be accomplished by either estimating the approximate number of grapes on each dish, or by assessing nonnumerical properties of the dishes such as their volume, weight, or size. It is still unclear which of the two approaches is used by people and animals to solve approximate numerical discriminations. This dissertation assessed the role that numerical and nonnumerical information has on discrimination responses made by pigeons and humans when given the choice between two visual displays of items. In a series of experiments both species were trained and tested in identical discrimination tasks in which we manipulated the numerical and nonnumerical properties of the training stimuli. Results demonstrate that pigeons and humans adjust the amount of numerical and nonnumerical information they use to inform their choices according to the task they are solving in any given moment.
- Academic Unit
- Psychological and Brain Sciences
- Record Identifier
- 9984830824002771
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