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Master of Science (M.S.)
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An ensemble representation refers to a statistical summary representation of a group of similar objects. Recent work has shown that we can form multiple ensemble representations – ensemble representations for a single feature dimension across multiple stimulus groups, ensemble representations for multiple feature dimensions in the same stimulus group, and ensemble representations across multiple sensory domains. In our study, we use hierarchical stimuli based on the Navon figures (Navon 1977) to study properties of ensemble representations across multiple spatial scales. In Experiments 1 and 3, we study properties of ensemble representations for the orientation and size feature dimension, respectively. In Experiment 2, we study properties of individual representations for the orientation feature dimension. Results indicate that it is possible to form ensemble representations across multiple spatial scales. Experiment 1 shows that the global ensemble representations may be extracted automatically (without intent) whereas the local ensemble representation is only extracted in response to task demands (with intent). Finally, in both Experiment 1 and Experiment 3, participants were more accurate at reporting the global ensemble representation than the local ensemble representation whereas in Experiment 2, performance did not differ across the levels. These results point towards global precedence in the formation of ensemble representations.
pandey, sandarsh, "Hierarchical Ensemble Representations: Forming Ensemble Representations across Multiple Spatial Scales" (2020). Masters Theses. 981.