Acknowledgments
We thank Laura Lobasso, Giovanni Ghirlanda, Carl-Adam Wachtmeister and Noel
Holmgren for their help. The research was supported by grants from the Swedish
Science Research Council and Marianne och Marcus Wallenbergs Stiftelse.
We thank Angela K. Turner at Animal Behaviour and Stuart Moffat at Aca-
demic Press for returning us the diskette with the manuscript: our copy was lost
in a computer accident.
References
Baerends, G. 1982. The hering gull and its egg. Part II. The responsiveness to
egg-features. Behaviour, 82, 358-363.
Churchland, P. & Sejnowski, T. 1992. The computational brain. Cambridge, MA:
MIT Press.
Czaplicki, J. A., Borrebach, D. E. & Wilcoxon, H. C. 1976. Stimulus generaliza-
tion of an illness-induced aversion to different intensities of colored water in
Japanese quail. Animal Learning & Behavior, 4, 45-48.
Dawkins, M. & Guilford, T. 1995. An exaggerated preference for simple neural
network models of signal evolution? Proceedings of the Royal Society, Series
B, 261, 357-360.
Dougherty, D. M. & Lewis, P. 1991. Stimulus generalization, discrimination
learning, and peak shift in horses. Journal of the Experimental Analysis of
Behavior, 56, 97-104.
Enquist, M. & Ghirlanda, S. 1998. The secrets of faces. Nature, 394, 826-827.
Enquist, M. & Leimar, O. 1993. The evolution of cooperation in mobile organ-
isms. Animal Behaviour, 45, 747-757.
Grice, G. R. & Saltz, E. 1950. The generalization of an instrumental response to
stimuli varying in the size dimension. Journal of Experimental Psychology, 40,
702-708.
Guttman, N. & Kalish, H. 1956. Discriminability and stimulus generalization.
Journal of Experimental Psychology, 51, 79-88.
Guyon, I. P. 1991. Applications of neural networks to character recognition. Inter-
national Journal of Pattern Recognition and Artificial Intelligence, 5, 353-382.
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