Pigeons’ serial ordering of numerosity with visual arrays

Abstract

Pigeons were trained in a conditional discrimination paradigm to differentiate successively presented visual arrays according to the relative number of their elements, Transfer tests with novel stimuli demonstrated that they discriminated the categories of "many" (6 or 7) from "few" (lor 2) items. In further tests, other new stimuli were introduced that consisted not only of these training numerosities, but also ofthe intervening ones (3, 4, and 5). Variationsin the birds' discrimination performance corresponded to the order of stimuli on a numerosity dimension. This serial ordering was maintained when other factors such as brightness, size, shape, area, and contour of the elements were systematically controlled across tests. Smaller numerosities were somewhat better discriminated than those at the higher end of this test range.

A neural model of how the brain represents and compares multi-digit numbers: spatial and categorical processes

“…It has been hypothesized for over 30 years (Fairbank, 1969;Restle, 1970) that an analog spatial representation of number exists in the brain; see Dehaene (1997) for an overview. The hypothesis that this representation is modality-independent and exists at a low cognitive level is supported by modality transfer experiments with rats (Church & Meck, 1984) and pigeons (Emmerton, Lohmann, & Niemann, 1997). In these studies, animals were able to extract the numerical properties from the stimuli in visual and auditory modalities, and then to combine the numerical information on an abstract level to produce correct responses.…”

“…For example, animals as simple as honeybees are able to discriminate the amount and frequency of reward in appetitive conditioning experiments (Buchanan & Bitterman, 1998). Pigeons can abstract the information about the relative number of items in small visual arrays, independent of other parameters of the stimuli (Emmerton, Lohmann, & Niemann, 1997). Modality transfer experiments demonstrated that rats can learn the number of events in a visual or auditory sequence (flashes and beeps) and then respond to a mixed auditory-visual sequence with the same total number of events (Church & Meck, 1984).…”

The pigeon’s discrimination of visual entropy: A logarithmic function

“…More important, however, is the fact that variability and other abstractions such as number and oddity represent concepts that are not readily reducible to a basic perceptual property of the stimulus itself (e.g., Emmerton, Lohmann, & Niemann, 1997;Thompson & Oden, 2000;Wasserman, Fagot, & Young, 2001;Young & Wasserman, 2001b). An organism can judge the variability of a collection and the number of items in that collection regardless of the items that constitute the collection.…”

Pigeons’ discrimination of color proportion in computer-generated visual displays

“…If, for instance, an animal really responds to the number of items it sees or hears, it must maintain its behavior when the size or shape of visual items is altered or when the duration of a series of sounds is manipulated. A variety of studies on numerical and temporal discriminations have incorporated such controls (e.g., Brannon & Terrace, 2000;Emmerton, Lohmann, & Niemann, 1997;Honig, 1992;Meck & Church, 1983;Roberts & Mitchell, 1994).…”