Small numerosity advantage for sequential enumeration on RSVP stimuli: an object individuation-based account

  • Xiaorong Cheng
  • Chunyan Lin
  • Chunmiao Lou
  • Weiwei Zhang
  • Yaqian Han
  • Xianfeng DingEmail author
  • Zhao FanEmail author
Original Article


Although there is a large literature demonstrating rapid and accurate enumeration of small sets of simultaneously presented items (i.e., subitizing), it is unclear whether this small numerosity advantage (SNA) can also manifest in sequential enumeration. The present study thus has two aims: to establish a robust processing advantage for small numerosities during sequential enumeration using a rapid serial visual presentation (RSVP) paradigm, and to examine the underlying mechanism for a SNA in sequential enumeration. The results indicate that a small set of items presented in fast sequences can be enumerated accurately with a high precision and a SOA (stimulus onset asynchrony)-sensitive capacity limit, essentially generalizing the large literature on small numerosity advantage from spatial domain to temporal domain. A resource competition hypothesis was proposed and confirmed in further experiments. Specifically, sequential enumeration and other cognitive process, such as visual working memory (VWM), compete for a shared resource of object individuation by which items are segregated as individual entities. These results implied that the limited resource of object individuation can be allocated within time windows of flexible temporal scales during simultaneous and sequential enumerations. Taken together, the present study calls for attention to the dynamic aspect of the enumeration process and highlights the pivotal role of object individuation in underlying a wide range of mental operations, such as enumeration and VWM.


Author contributions

All authors designed the study. XC and CL programmed the task and performed data analyses (along with CL). All authors contributed to manuscript preparation.


This work was made possible by grants from the National Natural Science Foundation of China (31500869 and 31671122), China Scholarship Council (201806775014 and 201806775017) and the Fundamental Research Funds for the Central Universities, China (CCNU18TS037, CCNU19TS039, CCNU17TS025, CCNU19TS075 and CCNU19TD019).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee, the American Psychological Association (APA) standards and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all the individual participants included in the study.

Supplementary material

426_2019_1264_MOESM1_ESM.rar (48 kb)
Supplementary material 1 (RAR 48 kb)


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Authors and Affiliations

  1. 1.Central China Normal University, School of PsychologyWuhanChina
  2. 2.Key Laboratory of Adolescent Cyberpsychology and Behavior (CCNU), Ministry of EducationWuhanChina
  3. 3.Key Laboratory of Human Development and Mental Health of Hubei ProvinceWuhanChina
  4. 4.Department of PsychologyUniversity of California at RiversideRiversideUSA

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