Perception & Psychophysics

, Volume 22, Issue 3, pp 265-276

First online:

Scaling of dot numerosity

  • Tarow IndowAffiliated withKeio University
  • , Masashi IdaAffiliated withKeio University


Subjective impression of numerosity of dots randomly scattered in an area of 19.5 × 24.5 cm, 36≈1,010 in number (ϕ), was scaled by four different methods with five subjects. The absolute identification showed that the number of dots is underestimated if ϕ > 10. Each of two scales based uponratio judgments is a power function of $ with the exponent of 0.87, and each of two scales based upondifference judgments is also a power function of ϕ when the origin of the scale is appropriately defined. The relationship between the four scales and comparison with scales in other sense modalities were discussed from the viewpoint of scaling methodology.