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Clement, T. S., Weaver, J. E., Sherburne, L. M., & Zentall, T. R. (1998). Simultaneous discrimination learning in pigeons: value of S- affects the relative value of its associated S+. Q J Exp Psychol B, 51(4), 363–378.
Abstract: In a simple simultaneous discrimination involving a positive stimulus (S+) and a negative stimulus (S-), it has been hypothesized that positive value can transfer from the S+ to the S- (thus increasing the relative value of the S-) and also that negative value can transfer from the S- to the S+ (thus diminishing the relative value of the S+; Fersen, Wynne, Delius, & Staddon, 1991). Evidence for positive value transfer has been reported in pigeons (e.g. Zentall & Sherburne, 1994). The purpose of the present experiments was to determine, in a simultaneous discrimination, whether the S- diminishes the value of the S+ or the S- is contrasted with the S+ (thus enhancing the value of the S+). In two experiments, we found evidence for contrast, rather than value transfer, attributable to simultaneous discrimination training. Thus, not only does the S+ appear to enhance the value of the S-, but the S- appears to enhance rather than reduce the value of the S+.
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Lachmann M., & Bergstrom C.T. (1998). Signalling among Relatives II. Beyond the Tower of Babel. Theor. Pop. Biol., 54(2). Retrieved June 6, 2024, from http://www.santafe.edu/~dirk/papers/SigII.pdf
Abstract: Models of costly signalling are commonly employed in evolutionary biology in order to explain how honest communication between individuals with conflicting interests can be stable. These models have focused primarily on a single type of honest signalling equilibrium, the separating equilibrium in which any two different signallers send distinct signals, thereby providing signal receivers with complete information. In this paper, we demonstrate that in signalling among relatives (modelled using the Sir Philip Sidney game), there is not one but a large number of possible signalling equilibria, most of which are pooling equilibria in which different types of signallers may share a common signal. We prove that in a general Sir Philip Sidney game, any partition of signallers into equi-signalling classes can have a stable signalling equilibrium if and only if it is a contiguous partition, and provide examples of such partitions. A similar (but slightly stricter) condition is shown to hold when signals are transmitted through a medium with signalling error. These results suggest a solution to a problem faced by previous signalling theory models: when we consider the separating equilibrium, signal cost is independent of the frequency of individuals sending that signal and, consequently, even very rare signaller types can drastically affect signal cost. Here, we show that by allowing these rare signallers to pool with more common signallers, signal cost can be greatly reduced. Copyright 1998 Academic Press.
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Bergstrom, C. T., & Lachmann, M. (1998). Signaling among relatives. III. Talk is cheap. Proc. Natl. Acad. Sci. U.S.A., 95(9), 5100–5105.
Abstract: The Sir Philip Sidney game has been used by numerous authors to show how signal cost can facilitate honest signaling among relatives. Here, we demonstrate that, in this game, honest cost-free signals are possible as well, under very general conditions. Moreover, these cost-free signals are better for all participants than the previously explored alternatives. Recent empirical evidence suggests that begging is energetically inexpensive for nestling birds; this finding led some researchers to question the applicability of the costly signaling framework to nestling begging. Our results show that cost-free or inexpensive signals, as observed empirically, fall within the framework of signaling theory.
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Coleman, K., & Wilson, D. S. (1998). Shyness and boldness in pumpkinseed sunfish: individual differences are context-specific. Anim. Behav., 56(4), 927–936.
Abstract: Natural selection often promotes a mix of behavioural phenotypes in a population. Adaptive variation in the propensity to take risks might explain individual differences in shyness and boldness in humans and other species. It is often implicitly assumed that shyness and boldness are general personality traits expressed across many situations. From the evolutionary standpoint, however, individual differences that are adaptive in one context (e.g. predator defence) may not be adaptive in other contexts (e.g. exploration of the physical environment or intraspecific social interactions). We measured the context specificity of shyness and boldness in a natural population of juvenile pumpkinseed sunfish,Lepomis gibbosus, by exposing the fish to a potentially threatening stimulus (a red-tipped metrestick extended towards the individual) and a nonthreatening stimulus (a novel food source). We also related these measures of shyness and boldness to behaviours observed during focal observations, both before and after the introduction of a predator (largemouth bass,Micropterus salmoides). Consistent individual differences were found within both contexts, but individual differences did not correlate across contexts. Furthermore, fish that were scored as intermediate in their response to the metrestick behaved most boldly as foragers and in response to the bass predators. These results suggest that shyness and boldness are context-specific and may not exist as a one-dimensional behavioural continuum even within a single context.
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Astié, A. A., Kacelnik, A., & Reboreda, J. C. (1998). Sexual differences in memory in shiny cowbirds. Anim. Cogn., 1(2), 77–82.
Abstract: Avian brood parasites depend on other species, the hosts, to raise their offspring. During the breeding season, parasitic cowbirds (Molothrus sp.) search for potential host nests to which they return for laying a few days after first locating them. Parasitic cowbirds have a larger hippocampus/telencephalon volume than non-parasitic species; this volume is larger in the sex involved in nest searching (females) and it is also larger in the breeding than in the non-breeding season. In nature, female shiny cowbirds Molothrus bonariensis search for nests without the male's assistance. Here we test whether, in association with these neuroanatomical and behavioural differences, shiny cowbirds display sexual differences in a memory task in the laboratory. We used a task consisting of finding food whose location was indicated either by the appearance or the location of a covering disk. Females learnt to retrieve food faster than males when food was associated with appearance cues, but we found no sexual differences when food was associated with a specific location. Our results are consistent with the view that parasitism and its neuroanatomical correlates affect performance in memory tasks, but the effects we found were not in the expected direction, emphasising that the nature of avian hippocampal function and its sexual differences are not yet understood.
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Cox, G., & Ashford, T. (1998). Riddle Me This: The Craft and Concept of Animal Mind. Science Technology Human Values, 23(4), 425–438.
Abstract: This article examines the relations between methods used in both animal work and study and concepts of animal mind. By “animal work” the authors mean humans and animals working together, and by “animal study” they mean the discipline of ethology, especially the emerging area of cognitive ethology. Within these areas the wide range of conceptions of animal mind includes varying emphases on intelligence, forms of rationality and language, cognition, consciousness, and intentionality. The authors' central concern is to elucidate the vocabulary and the concepts which seem necessary to establishing successful working relationships with sheepdogs and gundogs. Their argument moves toward an emphasis on the appreciation of particular intentional states and recognizes that they invariably deploy elements of a moral vocabulary in achieving creative teamwork performances with dogs and other animals. The article concludes by consid enng the relevance of accounts of work with animals for associated considerations of intentionality.
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Mesulam, M. - M. (1998). Review article. From sensation to cognition. Brain, 121, 1013–1052.
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Kesel, L., & Neil, D. H. (1998). Restraint and handling of animals. Clinical Textbook for Veterinary Technicians. 4th ed., , 1–26.
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Khalil, A. M., Murakami, N., & Kaseda, Y. (1998). Relationship between plasma testosterone concentrations and age, breeding season and harem size in Misaki feral horses. J Vet Med Sci, 60(5), 643–645.
Abstract: Jugular vein blood samples were collected from 23 young and sexual mature feral stallions to examine the relationship between plasma testosterone concentration and age, breeding season or harem size. Testosterone concentration increased with the age of the stallions until they formed their own harems, at about 4 to 6 years old. Seasonal variations in testosterone concentrations were observed, and found to be significantly higher (P<0.001) throughout the breeding season than non-breeding season, from 3 years of age. Testosterone levels were correlated with harem size for individual stallions. It can be inferred from these results that there is a relationship between plasma testosterone concentration and age, breeding season and harem size.
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Blokland, A. (1998). Reaction time responding in rats. Neurosci Biobehav Rev, 22(6), 847–864.
Abstract: The use of reaction time has a great tradition in the field of human information processing research. In animal research the use of reaction time test paradigms is mainly limited to two research fields: the role of the striatum in movement initiation; and aging. It was discussed that reaction time responding can be regarded as “single behavior”, this term was used to indicate that only one behavioral category is measured, allowing a better analysis of brain-behavior relationships. Reaction time studies investigating the role of the striatum in motor functions revealed that the initiation of a behavioral response is dependent on the interaction of different neurotransmitters (viz. dopamine, glutamate, GABA). Studies in which lesions were made in different brain structures suggested that motor initiation is dependent on defined brain structures (e.g. medialldorsal striatum, prefrontal cortex). It was concluded that the use of reaction time measures can indeed be a powerful tool in studying brain-behavior relationships. However, there are some methodological constraints with respect to the assessment of reaction time in rats, as was tried to exemplify by the experiments described in the present paper. On the one hand one should try to control for behavioral characteristics of rats that may affect the validity of the parameter reaction time. On the other hand, the mean value of reaction time should be in the range of what has been reported in man. Although these criteria were not always met in several studies, it was concluded that reaction time can be validly assessed in rats. Finally, it was discussed that the use of reaction time may go beyond studies that investigate the role of the basal ganglia in motor output. Since response latency is a direct measure of information processing this parameter may provide insight into basic elements of cognition. Based on the significance of reaction times in human studies the use of this dependent variable in rats may provide a fruitful approach in studying brain-behavior relationships in cognitive functions.
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