Across the natural world as well as the artificial worlds of maps, diagrams, and data visualizations, feature similarity (e.g., color and shape) links spatially separate areas into sets. Despite a century of study, it is yet unclear what mechanism underlies this gestalt similarity grouping. One recent proposal is that similarity grouping—for example, seeing a red, vertical, or square group—is just global selection of those features. Although parsimonious, this account makes the counterintuitive prediction that similarity grouping is strictly serial: A green group cannot be constructed at the same time as a red group. We tested this prediction with a novel measure—a grouping illusion within number-estimation tasks that should work only if participants simultaneously construct groups—and found the strongest evidence yet in favor of serial feature-based attention (Ns = 14, 12, and 12 for Experiment 1, Experiment 2, and Experiment 3, respectively).
|Date made available||2019|