Subitizing object parts reveals a second stage of individuation

Marlene Poncet* (Corresponding Author), Ramakrishna Chakravarthi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
4 Downloads (Pure)


Humans can efficiently individuate a small number of objects. This subitizing ability is thought to be a consequence of limited attentional resources. However, how and what is selected during the individuation process remain outstanding questions. We investigated these in four experiments by examining if parts of objects are enumerated as efficiently as distinct objects in the presence and absence of distractor objects. We found that distractor presence reduced subitizing efficiency. Crucially, parts connected to multiple objects were enumerated less efficiently than independent objects or parts connected to a single object. These results argue against direct individuation of parts and show that objecthood plays a fundamental role in individuation. Objects are selected first and their components are selected in subsequent steps. This reveals that individuation operates sequentially over multiple levels.
Original languageEnglish
Pages (from-to)476-486
Number of pages11
JournalPsychonomic Bulletin and Review
Early online date17 Nov 2020
Publication statusPublished - Apr 2021

Bibliographical note

Open Practices Statement
The experimental programs, data and code for data analysis for all studies are made available publicly available on OSF at None of the experiments were preregistered.


  • subitizing
  • visual attention
  • enumeration
  • object recognition
  • individuation
  • Enumeration
  • Individuation
  • Brief Report
  • Subitizing
  • Object recognition
  • Visual attention


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