Bateson Melissa, Healy Susan D, Hurly T Andrew
Evolution and Behaviour Research Group, School of Biology, University of Newcastle upon Tyne, Henry Wellcome Building for Neuroecology, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
Proc Biol Sci. 2003 Jun 22;270(1521):1271-6. doi: 10.1098/rspb.2003.2365.
A core assumption implicit in economic models of animal choice is that subjects assign absolute utilities to options that are independent of the type and number of alternatives available. Humans sometimes appear to violate this assumption and employ relative, as opposed to absolute, currencies when making choices. Recent evidence suggests that animals too might sometimes employ relative choice mechanisms. We tested this idea by measuring the foraging preferences of rufous hummingbirds (Selasphorus rufus) faced with choices analogous to those in which human use of relative currencies is evident. The birds experienced three treatments: a binary choice between two artificial flower types designated concentration (20 microl, 40% sucrose solution) and volume (40 microl, 20%), and two trinary treatments in which a third decoy option (either concentration decoy: 10 microl, 30% or volume decoy: 30 microl, 10%) was added to the set. The birds' preferences differed significantly across the three treatments. In the trinary treatments, the effect of the decoy options was to increase the preference for the option that dominated the decoy. These results are similar to those reported in the human choice literature, and are compatible with the hummingbirds using a relative evaluation mechanism in decision making.
动物选择的经济模型中隐含的一个核心假设是，主体会为各种选项赋予绝对效用，且这些效用独立于可用替代选项的类型和数量。人类在做出选择时，有时似乎会违背这一假设，采用相对而非绝对的衡量标准。最近的证据表明，动物有时也可能采用相对选择机制。我们通过测量棕煌蜂鸟（Selasphorus rufus）的觅食偏好来验证这一想法，这些偏好选择类似于人类明显使用相对衡量标准的情况。这些鸟经历了三种处理方式：在两种人工花类型之间进行二元选择，分别为浓度（20微升，40%蔗糖溶液）和体积（40微升，20%），以及两种三元处理方式，即在选择组中添加第三个诱饵选项（要么是浓度诱饵：10微升，30%；要么是体积诱饵：30微升，10%）。在这三种处理方式中，鸟的偏好存在显著差异。在三元处理方式中，诱饵选项的作用是增加对主导诱饵的选项的偏好。这些结果与人类选择文献中报道的结果相似，并且与蜂鸟在决策时使用相对评估机制相一致。
