August 2023
Volume 23, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2023
Does visual distinctiveness from an unexpected feature dimension facilitate search?
Author Affiliations & Notes
  • Zoe (Jing) Xu
    University of Illinois, Urbana Champaign
  • Alejandro Lleras
    University of Illinois, Urbana Champaign
  • John E. Hummel
    University of Illinois, Urbana Champaign
  • Simona Buetti
    University of Illinois, Urbana Champaign
  • Footnotes
    Acknowledgements  This material is based upon work supported by the National Science Foundation under Grant No BCS1921735 to SB.
Journal of Vision August 2023, Vol.23, 5896. doi:
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      Zoe (Jing) Xu, Alejandro Lleras, John E. Hummel, Simona Buetti; Does visual distinctiveness from an unexpected feature dimension facilitate search?. Journal of Vision 2023;23(9):5896.

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      © ARVO (1962-2015); The Authors (2016-present)

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Previous research showed that when a target differs from distractors along both color and shape dimensions, search is faster than when only one dimension is available (Buetti et al., 2019). This result was found when participants expected targets and distractor to differ along both dimensions. What if participants only expect a featural difference along one dimension, while one actually exists along both dimensions? Will information in the unexpected dimension improve search efficiency? Here we tested this question in ten experiments. In Experiment 1, we tested people’s search efficiency when the target differed from a set of homogeneous distractors along either color (Experiment 1A) or shape (Experiment 1B). In Experiments 1C-E, participants searched for a target that differed from distractors along both dimensions. Participants were instructed to search by color (Experiment 1C), by shape (Experiment 1D), or both (control group - Experiment 1E). Results showed that people searched faster in the control group compared to color- or shape-focused groups. In Experiment 2, we added uncertainty to the target identity in the unexpected dimension. Experiment 2A setting was identical to Experiment 1A. Experiments 2B-C were similar to Experiment 1B except that the target shape changed randomly across trials. Finally, in Experiments 2D-E, participants searched for the target among distractors that differed along both dimensions, though participants were instructed to search only based on color. Critically, the shape of the target changed randomly across trials, so participants could never anticipate it. Results showed that participants still searched faster when there were featural differences along both feature dimensions, even when they could not anticipate what the target shape would be. Overall, these results indicate that search is simultaneously facilitated by both top-down (known target color) and bottom-up (unknown target shape) information, even when observers are asked to focus exclusively on a single feature dimension.


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