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A preference test is an experiment in which animals are allowed free access to multiple environments which differ in one or more variants. Various aspects of the animal's behaviour can be measured such as latency to approach the variants, relative consumption of variants, the number of entries and duration of time spent in different environments, or the range of activities in each of the environments. These measures can be recorded either by the experimenter or by motion detecting software. Statistical testing is used to determine whether the differences are large enough in comparison to the control group or the individual animal, to conclude that preference or aversion has occurred. Strength of preference can be inferred by the magnitude of the difference in the response, but see "Advantages and disadvantages" below. Prior to testing, the animals are usually given the opportunity to explore the apparatus and variants to habituate and reduce the effects of novelty. Preference tests can be used to test for preferences of only one characteristic of the variant, e.g. cage colour, or multiple characteristics of complex variants e.g. a choice between hamster wheel, Habitrail tunnels or additional empty space for extended locomotion.〔Sherwin, C.M., (1998). The use and perceived importance of three resources which provide caged laboratory mice the opportunity of extended locomotion. Applied Animal Behaviour Science, 55: 353-367〕 == Types of test == ; Two variants: The simplest of preference tests offers a choice between two variants. This can be achieved using different variants at the ends of the arms of a 'T' shaped maze, or having a chamber divided in half with one variant available in one half and the other variant available in the other half. A famous example of this simple method is an investigation of the preferences of chickens for different types of wire floor in battery cages. Two types of metal mesh flooring were being used in the 1950s; one type was a large, open mesh using thick wire, the other was a smaller mesh size but the wire was considerably thinner. A prestigious committee, the Brambell Committee, conducting an investigation into farm animal welfare〔Thorpe, W.H., (1965). The assessment of pain and distress in animals. Appendix III in report of the technical committee to enquire into the welfare of animals kept under intensive husbandry conditions, F.W.R.Brambell (chairman). H.M.S.O., London〕 concluded the thicker mesh should be used as this was likely to be more comfortable for the chickens. However, preference tests showed that chickens preferred the thinner wire. Photographs taken from under the cages showed that the thinner mesh offered more points of contact for the feet than the thick mesh, thereby spreading the load on the hens' feet and presumably feeling more comfortable to the birds. ; Multiple variants: The number of variants that can be offered is theoretically limitless for some preference tests, e.g. light intensity, cage size, food types, however, the number is often limited by experimental practicalities, current practice (e.g. animal caging systems) or costs. Furthermore, animals usually investigate all areas of the apparatus, even those areas of minor preference, meaning that differences in behaviour become less distinct as the number of variants increases. ; Variants requiring a cost: (詳細はウィキペディア（Wikipedia）』 ■ウィキペディアで「Preference test」の詳細全文を読む スポンサード リンク
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