If you ever get the impression that your dog can "tell" whether you look content or annoyed, you may be onto something. Dogs may indeed be able to distinguish between happy and angry human faces, according to a new study.

Researchers trained a group of 11 dogs to distinguish between images（图像）of the same person making either a happy or an angry face. During the training stage, each dog was shown only the upper half or the lower half of the person's face. The researchers then tested the dogs' ability to distinguish between human facial expressions by showing them the other half of the person's face or images totally different from the ones used in training. The researchers found that the dogs were able to pick the angry or happy face by touching a picture of it with their noses more often than one would expect by random chance.

The study showed the animals had figured out how to apply what they learned about human faces during training to new faces in the testing stage. "We can rule out that the dogs simply distinguish between the pictures based on a simple cue, such as the sight of teeth," said study author Corsin Muller. "Instead, our results suggest that the successful dogs realized that a smiling mouth means the same thing as smiling eyes, and the same rule applies to an angry mouth having the same meaning as angry eyes.”

"With our study, we think we can now confidently conclude that at least some dogs can distinguish human facial expressions," Muller told Live Science.

At this point, it is not clear why dogs seem to be equipped with the ability to recognize different facial expressions in humans. "To us, the most likely explanation appears to be that the basis lies in their living with humans, which gives them a lot of exposure to human facial expressions," and this exposure has provided them with many chances to learn to distinguish between them, Muller said.

    It was one of those terribly hot days in Baltimore. Needless to say, it was too hot to do anything outside. But it was also scorching in our apartment. This was 1962, and I would not live in a place with an air conditioner for another ten years. So my brother and I decided to leave the apartment to find someplace indoors. He suggested we could see a movie. It was a brilliant plan.

    Movie theaters were one of the few places you could sit all day and—most important —sit in air conditioning. In those days, you could buy one ticket and sit through two movies. Then, the theater would show the same two movies again. If you wanted to, you could sit through them twice. Most people did not do that, but the manager at our theater. Mr. Bellow did not mind if you did.

    That particular day, my brother and I sat through both movies twice, trying to escape the heat. We bought three bags of popcorn and three sodas each. Then, we sat and watched The Music Man followed by The Man Who Shot Liberty Valance. We'd already seen the second movie once before. It had been at the theater since January, because Mr. Bellow loved anything with John Wayne in it.

    We left the theater around 8, just before the evening shows began. But we returned the next day and saw the same two movies again, twice more. And we did it the next day too. Finally, on the fourth day, the heat wave broke.

    Still, to this day I can sing half the songs in The Music Man and recite half of John Wayne and Jimmy Stewart's dialogue from The Man Who Shot Liberty Valance! Those memories are some of the few I have of the heat wave of 1962. They're really memories of the screen, not memories of my life.

Leslie Nielsen's childhood was a difficult one, but he had one particular shining star in his life — his uncle, who was a well-known actor. The admiration and respect his uncle earned inspired Nielsen to make a career（职业）in acting. Even though he often felt he would be discovered to be a no-talent, he moved forward, gaining a scholarship to the Neighborhood Playhouse and making his first television appearance a few years later in 1948. However, becoming a full-time, successful actor would still be an uphill battle for another eight years until he landed a number of film roles that finally got him noticed.

But even then, what he had wasn't quite what he wanted. Nielsen always felt he should be doing comedy but his good looks and distinguished voice kept him busy in dramatic roles. It wasn't until 1980—32 years into his career — that he landed the role it would seem he was made for in Airplane! That movie led him into the second half of his career where his comedic presence alone could make a movie a financial success even when movie reviewers would not rate it highly.

Did Nielsen then feel content in his career? Yes and no. He was thrilled to be doing the comedy that he always felt he should do, but even during his last few years, he always had a sense of curiosity, wondering what new role or challenge might be just around the corner. He never stopped working, never retired.

Leslie Nielsen's devotion to acting is wonderfully inspiring. He built a hugely successful career with little more than plain old hard work and determination. He showed us that even a single desire, never given up on, can make for a remarkable life.