Numerical reproduction in pigeons.

Abstract

Pigeons were trained to match the number of responses made during a production phase to the number of keylight flashes (2, 4, or 6) in a previous sample phase. In Experiment 1, there were 2 conditions in which the flashes were programmed to occur at a constant rate or within a constant overall duration. For both conditions, although accuracy was relatively low, responding increased linearly with flash number and coefficients of variation decreased. Positive transfer to novel numbers was obtained only when test and baseline trials had the same temporal organization, but multiple regressions revealed significant control by number independently of temporal cues. In Experiment 2, flashes were programmed to occur pseudorandomly to degrade the validity of temporal cues. Results were similar to in Experiment 1. A prototype response class model accounted for the major features of the data. According to the model, responses during the production phase are shaped into higher order units that are associated with different stimulus numbers and function as a rough category scale of numerosity.

Human nonverbal discrimination of relative and absolute number

“…Yet relatively few studies have directly compared human and nonhuman performance, and those have been limited mostly to nonhuman primates and relative numerosity discriminations (Beran, Johnson-Pynn, & Ready, 2008;Jordan & Brannon, 2006a, b). The aim of the present experiment was to investigate further the processes underlying the nonverbal discrimination of number; it replicates and extends previous research with pigeons by Tan, Grace, Holland, and McLean (2007) and Tan and Grace (2010) with human participants in both relative and absolute numerical tasks.…”

“…Randomizing the interflash intervals and the total duration of the sample phase controlled the influence of temporal cues. Tan et al (2007) found that response number increased linearly with flash number and showed positive transfer to novel numbers from 1 to 7. Of particular interest, response variability was nonscalar and resembled binomial variability, where relative response variability decreased, instead of remaining constant, as number increased.…”

“…A major question was whether responding in the nonverbal discriminations would show bisection at the arithmetic mean and decreasing relative response variability, similar to pigeons' responding in analogous tasks (Tan & Grace, 2010;Tan et al, 2007).…”

“…Tan et al (2007) trained pigeons in a numerical reproduction task. Following two, four, or six response-dependent keylight flashes in a sample phase and a brief retention interval, subjects were required to make a number of keypecks equal to the number of flashes, followed by an additional response on another key, to obtain food.…”

Discrimination and representation of relative numerosity in a bisection task by pigeons

“…The procedure was based on the numerical reproduction task developed by Tan, Grace, Holland, and McLean (2007), modified to investigate relative rather than absolute numerosity discrimination. Pigeons were presented with a sequence of response-dependent keylight flashes, after which they were required to make one of two responses.…”