"A study has found that dogs can be divided into two personality types based on their emotional outlook. 'Bowl-half-full' types are full of hopeful optimism, while their 'bowl-half-empty' kennelmates tend to expect the worst. The researchers believe they have shown scientifically for the first time that dogs experience the same sort of emotional states as people who are faced in similar half-full or half-empty scenarios. Dogs who are more pessimistic are also more likely to suffer other kinds of behaviour disorders, such as chewing up the furniture or howling uncontrollably when their owners leave them alone at home, the scientists said."