Does your dog know if you've had a bad day? Probably, but don't expect your cat to catch on.

Do chimpanzees understand why those who can't see them don't offer them treats?

Do vampire bats have the ability to show gratitude by returning a favor?

The answers depend on what is meant by "think," according to University of Florida psychology Professor Clive Wynne, who writes about these creature features and others in a new 244-page book, Do Animals Think?

While animals can do many clever things and even reason, they don't have the ability to reflect on what they are doing, one important element of thinking, said Wynne, who has studied animal behavior for 20 years in a variety of species ranging from pigeons to marsupials.

"Animals can learn, but whether learning always implies thinking is the question," he said. "Perhaps the take-home message is that each species thinks in its own way, a way that is adapted to the world it lives in."

Wynne said he decided to write the book after noticing that a number of "facts" about animals presented on popular television shows didn't stand up to closer inspection. Based on a careful study of publications in the field, he debunks some common myths, such as that chimpanzees understand language and dolphins use a sophisticated language based on their underwater vocalizations.

"This book takes a critical, iconoclastic and witty look at the claims for intelligence and language in other species, often made by sincere-if-fluffy and – sometimes just self-promoting – scientists," said Jonathan Marks, a molecular anthropologist at the University of North Carolina at Charlotte and author of the book "What it Means to be 98 percent Chimpanzee: Apes, People and their Genes." He said, "I had more fun reading this book than I have had from any other book in a long time."

The book also criticizes animal enthusiasts Jane Goodall, a primatologist, and Peter Singer, founder of the "Animal Liberation" philosophy, for humanizing animals, disagreeing with their positions that humans have few, if any, psychological abilities unique from animals.

"These people claim that because chimpanzees share 98 percent of humans' DNA material that means they must be 98 percent like us psychologically," he said. "But chimpanzees are not human beings running around in hairy suits."

While chimps can be taught to push the "right" button on a computer, they certainly cannot be taught anything resembling human communication. In contrast, the typical human 2-year-old learns an average of 300 new words every month, he said.

And while dolphins use sonar to identify different objects underwater and have an "amazing ability" to identify the consistency of the material of which an object is made, Wynne said, they don't communicate as humans do to exchange information.

Even the sexual habits of dolphins have been fodder for fallacies. "Have you ever heard that dolphins are the only species apart from humans that engage in sex for pleasure and not for procreation?" Wynne asked. "I've heard this so many times I always ask, 'So you mean that other animal species know when they're having sex that they're doing it in order to have offspring?'" At least among Australian dolphins sex is quite violent, with most females coerced into the activity, he said.

Another misunderstood critter is the Central American vampire bat, which, contrary to its foreboding name, happens to be the only nonhuman species to reciprocate goodwill, Wynne said. Vampire bats that don't get a blood meal once every third night die, he said, so if a bat goes back to the roost without one, it will beg from another, which will regurgitate blood to share.

"People have studied this in great detail, hanging around at the bottom of the roost, getting covered with bat guano," Wynne said. "And it turns out that bats can remember who helped them in the past and are more likely to spit up some blood for a bat who previously helped them."

Closer to home, cats and dogs completely differ in how they relate to their environment, particularly when it comes to people. Once social hunters, dogs desperately need to be part of a pack and will do anything to stay with their owners, even if mistreated. On the other hand, cats, which are independent hunters, are fairly unsocial and rather indifferent to humans.

"Your dog will never reject you, and it is brilliant at reading all of your behavior," he said.

A dog would waste no time begging for food from a person who could not see them, as an experiment by a Hungarian team of researchers showed. Given a choice between two people sitting on a park bench holding out liver-sausage sandwiches, the dogs in the experiment always chose the person who could see them over the one whose eyes were looking away, he said.

A similar experiment on chimps, however, showed they were as likely to beg from humans with buckets over their heads or blindfolds over their eyes as those looking straight at them, he said.

"Dogs have been living with humans, some say for as long as a hundred thousand years," Wynne said. "Reading human minds is not something that you do by being closely related to human beings. It's something that you do by spending thousands of generations hanging out with human beings and learning what humans are up to."

- Cathy Keen