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Perception & Psychophysics 1991, 50 (6), 555-564
 

Summary: Perception & Psychophysics
1991, 50 (6), 555-564
Is subitizing a unique numerical ability?
J. D. BALAKRISHNAN
Northwestern University, Evanston, Illinois
and
F. GREGORY ASHBY
University of California, Santa Barbara, California
Two models that predict the relation between mean enumeration time and numero8ity in a
speeded enumeration experiment are tested. The first is a bilinear two-process model, and the
second is a log-linear single-process model. Previously, support for the bilinear model has provided
evidencefor the existence of a unique numericalability called"subitizing." Both models are shown
toyield close approximations to the empirical data, but at the same time to consistently violate
the robust shape of these data. Two fundamental discrepanciesexist: (1) Enumeration of single-
element displaysis unpredictably fast,both in the data reported here and elsewhere, and (2) the
response-time function for multiple elements iscontinuously convex upward, with a significant
log-quadratic component. The findings support the contention that enumeration is a capacity-
limited process, butno statistically reliable change in processing character, that is, from subitiz-
ing to some other process, is evident in enumeration of displays of up to six elements.
In the "speeded enumeration" experiment, subjects re-

  

Source: Ashby, F. Gregory - Department of Psychology, University of California at Santa Barbara

 

Collections: Biology and Medicine; Computer Technologies and Information Sciences