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


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
JournalPsychonomic Bulletin and Review
Publication statusAccepted/In press - 20 Oct 2020


  • subitizing
  • visual attention
  • enumeration
  • object recognition
  • individuation

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