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Whiten, A., Horner, V., & de Waal, F. B. M. (2005). Conformity to cultural norms of tool use in chimpanzees. Nature, 437(7059), 737–740.
Abstract: Rich circumstantial evidence suggests that the extensive behavioural diversity recorded in wild great apes reflects a complexity of cultural variation unmatched by species other than our own. However, the capacity for cultural transmission assumed by this interpretation has remained difficult to test rigorously in the field, where the scope for controlled experimentation is limited. Here we show that experimentally introduced technologies will spread within different ape communities. Unobserved by group mates, we first trained a high-ranking female from each of two groups of captive chimpanzees to adopt one of two different tool-use techniques for obtaining food from the same 'Pan-pipe' apparatus, then re-introduced each female to her respective group. All but two of 32 chimpanzees mastered the new technique under the influence of their local expert, whereas none did so in a third population lacking an expert. Most chimpanzees adopted the method seeded in their group, and these traditions continued to diverge over time. A subset of chimpanzees that discovered the alternative method nevertheless went on to match the predominant approach of their companions, showing a conformity bias that is regarded as a hallmark of human culture.
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Wolff, A., & Hausberger, M. (1994). Behaviour of foals before weaning may have some genetic basis. Ethology, 96(1), 1–10.
Abstract: In this preliminary study on foal behaviour, 13 French saddlebred foals (2-3 mo old) and their dams were observed on pasture. The most important findings are the interindividual quantitative differences in foal behaviour patterns as well as in the amount of mainly foal-initiated time spent at given distances from their mares. Interindividual differences seem in part due to a sire effect
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Youket, R. J., Carnevale, J. M., Houpt, K. A., & Houpt, T. R. (1985). Humoral, hormonal and behavioral correlates of feeding in ponies: the effects of meal frequency. J. Anim Sci., 61(5), 1103–1110.
Abstract: The effect of meal frequency on body fluid, glucose, triiodothyronine (T3), heart rate and behavior was measured in 10 ponies. A simple reversal design was used in which each pony received one meal/day (1X) for 2 wk and six meals/day (6X) for 2 wk. The total intake/day was held constant. Feeding was followed by a rise in plasma levels of glucose, T3, protein and osmolality. One large meal was followed by significantly greater changes in all of the variables than was a meal one-sixth the size. Plasma T3 rose from 41 +/- 5 (SE) ng/liter before feeding to 43 +/- 5 ng/liter following a small meal, but rose significantly higher, from 39 +/- 4 to 60 +/- 10 ng/liter, following a large meal. Glucose rose from 84 +/- 3 to 109 +/- 7 mg/dl following a small meal and rose significantly higher, from 83 +/- 3 to 154 +/- 11 mg/dl, after a large meal. Plasma protein rose from 6.55 +/- .14 to 6.62 +/- .16 g/dl following a small meal and from 6.45 +/- .14 to 6.99 +/- .11 g/dl following a large meal. Osmolality rose from 227 +/- 1 mosmol/liter before to 279 +/- 1 mosmol/liter following a small meal and significantly higher from 278 +/- 2 to 285 +/- 1 mosnol/liter following a large meal. Heart rate rose from 42 beats/min in the absence of feed to 50 beats/min when food was visible to the ponies and did not rise higher when eating began. There were no significant differences in the cardiac response to one large meal and that to a small meal.(ABSTRACT TRUNCATED AT 250 WORDS)
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Zentall, T. R., & Sherburne, L. M. (1994). Role of differential sample responding in the differential outcomes effect involving delayed matching by pigeons. J Exp Psychol Anim Behav Process, 20(4), 390–401.
Abstract: The role of differential sample responding in the differential outcomes effect was examined. In Experiment 1, we trained pigeons on a one-to-many matching task with differential sample responding required. Differential outcomes were associated with samples and comparisons, with comparisons only, or with neither samples nor comparisons. Slopes of delay functions for trials with pecked versus nonpecked samples suggested use of a single-code-default strategy in the nondifferential-outcomes group but not in the differential-outcomes groups. In Experiment 2, differential sample responding and differential outcomes were manipulated independently. Again, there were significant differences in the relative slopes of the delay functions. Results suggest that differential outcomes exert their effect independently of differential sample responding.
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