Proops Leanne, Burden Faith, Osthaus Britta
Department of Psychology, University of Sussex, Falmer, Brighton, BN1 9QG, UK.
Anim Cogn. 2009 Jan;12(1):75-84. doi: 10.1007/s10071-008-0172-1. Epub 2008 Jul 18.
This study compares the behaviour of the mule (Equus asinus x Equus caballus) with that of its parent species to assess the effects of hybridization on cognition. Six mules, six ponies (E. caballus) and six donkeys (E. asinus) were given a two choice visual discrimination learning task. Each session consisted of 12 trials and pass level was reached when subjects chose the correct stimulus for at least 9 out of the 12 trials in three consecutive sessions. A record was made of how many pairs each subject learnt over 25 sessions. The mules' performance was significantly better than that of either of the parent species (Kruskal-Wallis: H(x) = 8.11, P = 0.017). They were also the only group to learn enough pairs to be able to show a successive reduction in the number of sessions required to reach criterion level. This study provides the first empirical evidence that the improved characteristics of mules may be extended from physical attributes to cognitive function.
本研究比较了骡子（Equus asinus x Equus caballus）与其亲本物种的行为，以评估杂交对认知的影响。给六头骡子、六匹小马（Equus caballus）和六头驴（Equus asinus）进行了二选一视觉辨别学习任务。每个实验环节包括12次试验，当受试者在连续三个实验环节的12次试验中至少有9次选择正确刺激时，即达到通过水平。记录了每个受试者在25个实验环节中学会的对子数量。骡子的表现明显优于任何一个亲本物种（Kruskal-Wallis检验：H(x)=8.11，P = 0.017）。它们也是唯一一组学会了足够多对子从而能够在达到标准水平所需的实验环节数量上呈现连续减少的组。本研究提供了首个实证证据，表明骡子的优良特性可能从身体属性扩展到了认知功能。
