Colour categorisation by domestic chicks

Jones, C D, Osorio, D and Baddeley, R J (2001) Colour categorisation by domestic chicks. Proceedings B: Biological Sciences, 268 (1481). pp. 2077-2084. ISSN 1471-2954

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Spectral stimuli form a physical continuum, which humans divide into discrete non¿overlapping regions or categories that are designated by colour names. Little is known about whether non¿verbal animals form categories on stimulus continua, but work in psychology and artificial intelligence provides models for stimulus generalization and categorization. We compare predictions of such models to the way poultry chicks (Gallus gallus) generalize to novel stimuli following appetitive training to either one or two colours. If the two training colours are (to human eyes) red and greenish¿yellow or green and blue, chicks prefer intermediates, i.e. orange rather than red or yellow and turquoise rather than green or blue. The level of preference for intermediate colours implies that the chicks interpolate between the training stimuli. However, they do not extrapolate beyond the limits set by the training stimuli, at least for red and yellow training colours. Similarly, chicks trained to red and blue generalize to purple, but they do not generalize across grey after training to the complementary colours yellow and blue. These results are consistent with a modified version of a Bayesian model of generalization from multiple examples that was proposed by Shepard and show similarities to human colour categorization.

Item Type: Article
Additional Information: Main author. (Devised study and wrote most of the paper, key input from Baddeley on modelling)
Schools and Departments: School of Life Sciences > Evolution, Behaviour and Environment
Depositing User: Daniel ColacoOsorio
Date Deposited: 06 Feb 2012 18:43
Last Modified: 22 May 2012 16:12
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