Automatic feature-based grouping during multiple object tracking

Gennady Erlikhman, Brian P. Keane, Everett Mettler, Todd S. Horowitz, Philip J. Kellman

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Contour interpolation automatically binds targets with distractors to impair multiple object tracking (Keane, Mettler, Tsoi, & Kellman, 2011). Is interpolation special in this regard or can other features produce the same effect? To address this question, we examined the influence of eight features on tracking: color, contrast polarity, orientation, size, shape, depth, interpolation, and a combination (shape, color, size). In each case, subjects tracked 4 of 8 objects that began as undifferentiated shapes, changed features as motion began (to enable grouping), and returned to their undifferentiated states before halting. We found that intertarget grouping improved performance for all feature types except orientation and interpolation (Experiment 1 and Experiment 2). Most importantly, target-distractor grouping impaired performance for color, size, shape, combination, and interpolation. The impairments were, at times, large (<15% decrement in accuracy) and occurred relative to a homogeneous condition in which all objects had the same features at each moment of a trial (Experiment 2), and relative to a "diversity" condition in which targets and distractors had different features at each moment (Experiment 3). We conclude that feature-based grouping occurs for a variety of features besides interpolation, even when irrelevant to task instructions and contrary to the task demands, suggesting that interpolation is not unique in promoting automatic grouping in tracking tasks. Our results also imply that various kinds of features are encoded automatically and in parallel during tracking.

Original languageEnglish (US)
Pages (from-to)1625-1637
Number of pages13
JournalJournal of Experimental Psychology: Human Perception and Performance
Issue number6
StatePublished - Dec 2013

All Science Journal Classification (ASJC) codes

  • Experimental and Cognitive Psychology
  • Arts and Humanities (miscellaneous)
  • Behavioral Neuroscience


  • Attention
  • Illusory contours
  • Multiple object tracking
  • Perceptual grouping
  • Perceptual organization

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