It’s been accepted as fact for donkey’s years – but it seems mules aren’t stubborn after all。
But in fact， experts say the animals are more adaptable and intelligent than horses and dogs。
An animal behaviour expert decided to test the stubbornness of mules by setting up a problem-solving task involving a fence being placed in a pen with food on the other side。
However， it was discovered that most horses and donkeys simply stopped in front of the obstacle and pause for some time。
Mules were also more flexible in their unlearning than dogs
The results showed that mules - the offspring of a female horse and male donkey - consistently spotted the gap almost immediately and bypassed the barrier。
The fence was moved several times but the test found that mules as a group would always solve the problem faster than donkeys， horses， and dogs。
Dr Britta Osthaus carried out out the test on 12 of each group to get a clear indication of which species is better at problem solving。
Britta， 46， a senior lecturer in Applied Social Sciences at Canterbury University， Kent， said： ‘First I tested dogs on this task and was surprised how badly they performed。
‘Then I thought that horses， mules and donkeys are prey animals， unlike dogs， and whether their thinking might be more efficient in this situation。
‘We don’t know much about the actual thinking abilities of horses， mules and donkeys and I was curious。
‘I tested it on 12 of each。
‘Mules were faster in their initial learning than both donkeys and horses and they were also more flexible in their unlearning than dogs and horses。
‘Donkeys also outshone both dogs and horses in their flexibility， completely the opposite to what we expect from stubborn donkeys。’
骡子又呆又笨，一直是公认的事实，但其实骡子似乎一点都不迟钝。据英国《每日邮报》报道，专家称骡子比马和狗更聪明，灵活性更强。
动物行为专家设置了一项问题解决型任务，以测试骡子的反应能力。在圈中放置围栏，围栏对面放食物。围栏的一侧有一个巨大的缺口，可以很容易绕过围栏。
但是，实验显示马和驴在围栏面前停止不前；而骡子——母马和公驴的后代——总能立即发现缺口绕过围栏。虽然将围栏移动多次，但实验显示骡子总能比驴、马和狗更快地解决问题。
坎特伯雷肯特大学应用社会学博士布丽塔·奥斯陶斯对每组动物分别选取12只进行试验，以弄清哪种动物更擅长解决问题。她说：“首先我测试的是狗，很惊讶地发现狗的表现很差。之后，我想，马、骡子和驴是被捕食动物，和狗不一样，在这种情况下它们的思维会不会更快。”
布丽塔·奥斯陶斯说：“骡子在最初学习方面比驴和马更快，不过忘性也比狗和马更大。驴的灵活性也比狗和马更好，完全与笨驴形象相反。”
