Incidental encoding of numerosity in visual long-term memory

Jiaying Zhao, Nicholas B. Turk-Browne

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The visual system can readily extract numerosity information from brief experiences. This numerical perception is characterized by diminishing accuracy as numerosity increases, and impaired discrimination for similar quantities and large magnitudes. Here we assess whether these properties apply more broadly to numerosity in visual long-term memory. In surprise memory tests, we observed: Remarkable accuracy in estimating the number of repetitions of an exemplar image (Experiment 1a), that this accuracy decreased but remained high when estimating over categories (Experiments 1b and 1c), that numerical discrimination from memory exhibited psychophysical distance and size effects (Experiment 2), that these effects may derive from stored representations rather than post hoc approximation (Experiment 3a), and that they can reflect total elapsed experience in addition to discrete counts (Experiment 3b). Similar to how numerosity is readily extracted during visual perception, our results suggest that numerosity is encoded incidentally in visual long-term memory.

Original languageEnglish (US)
Pages (from-to)928-955
Number of pages28
JournalVisual Cognition
Issue number7
StatePublished - Aug 2011

All Science Journal Classification (ASJC) codes

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


  • Distance effect
  • Incidental encoding
  • Numerosity
  • Size effect
  • Visual long-term memory


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