The colorful anemonefish (海葵鱼), also known as clownfish, possesses a cheerful and carefree image among humans. However, their actual behavior might not always align with the family-friendly portrayal seen in a Pixar film. They can aggressively defend their territory against other anemonefish they perceive as threats.

To investigate how these fish identify group members, a team from Japan conducted two experiments with lab-raised common clownfish that had never encountered any other species.

In the first experiment, researchers introduced different species of anemonefish, distinguishable by the number of white bars on their bodies, into a tank in small cases. They observed that the common clownfish were particularly hostile toward members of their own species that displayed three white bars. These fish fought 80 percent of their specific-targeted fish for up to three seconds. In contrast, invaders from other species, like the orange skunk clownfish with no side bars and a white line along its back, were barely attacked. The two-barred Clarke’s clownfish and three-barred saddleback clownfish were “mildly bullied”, according to the team.

During the second experiment, the researchers exposed a colony of clownfish to various plastic discs. The discs were painted with anemonefish coloration and measured the level of aggression towards these artificial models. Similar to reactions to live fish, models with two bars were less frequently attacked, and those without any bars saw the least aggression. According to study co-author and ecologist Kina Hayashi, the findings “suggest that clownfish is capable of counting the number of bars to recognize the species of the invader”.

The team also found that a rigid hierarchy (社会等级) within clownfish colonies determines which specific fish attack the invader. Earlier studies have shown that the social position of the clownfish is determined by very slight differences in size. This study used fish that had not matured and were in a lab setting, but the team still observed the same size-based hierarchy. The largest clownfish led the charge against the invader.

A robot with a sense of touch may one day feel “pain”, ‘both its own physical pain and sympathy-for the pain of its human companions. Such touchy-feely robots are still far off, but advances in robotic touch-sensing are bringing that possibility closer to reality.

Sensors set in soft, artificial skin that can detect both a gentle touch and a painful strike have been hooked up (连接) to a robot that can then signal emotions, Asada reported February 15 at the annual meeting of the American Association for the Advancement of Science. This artificial “pain nervous system”, as Asada calls it, may be a small building block for a machine that could experience pain. Such a feeling might also allow a robot to “sympathize” with a human companion’s suffering.

Asada, an engineer at Osaka University, and his colleagues have designed touch sensors that reliably pick up a range of touches. In a robot system named Affetto, a realistic-looking child’s head, these touch and pain signals can be converted to emotional facial expressions.

A touch-sensitive, soft material, as opposed to a rigid metal surface, allows richer interactions between a machine and the world, says neuroscientist Kingson Man of the University of Southern California. Artificial skin “allows the possibility of engagement in truly intelligent ways”.

Such a system, Asada says, might ultimately lead to robots that can recognize the pain of others, a valuable skill for robots designed to help care’ for people in need, the elderly, for instance. But there is an important distinction between a robot that responds in a predictable way to a painful strike and a robot that’s capable of approximating an internal feeling, says Damasio, a neuroscientist also at the University of Southern California. A robot with sensors that can detect touch and pain is “along the lines of having a robot, for example, that smiles when you talk to it,” Damasio says.

“While that’s an interesting development, it’s not the same thing as a robot designed to express some sort of internal experience,” he says.

When faced with the decision to get out of bed or have a few more minutes of sleep, which do you choose? Believe it or not, that decision could make a world of difference in the rest of your day.

About 85 percent of Americans use an alarm clock to wake up in the mornings, according to sleep researcher Till Roennenber. And while there are no official numbers on snoozing (打盹), a quick survey of social media makes it clear that hitting the snooze button is a popular pastime.

As to how the snooze button will affect your day, scientists have mixed opinions. Some scientists think people who hit the snooze button in the mornings are actually clever, creative and happy while some said that hitting the snooze button will ruin your life, or at the very least your day. "I feel that hitting the snooze button has got to be one of the worst things that ever happened to human sleep,” researcher Jonathan Horowitz said. "The chances of you ‘snoozing’ and actually experiencing a meaningful rest are close to zero.”

According to some sleep experts, when hitting the snooze button，you are in fact confusing your body and mind, and throwing yourself into a deep state of being sleepy. The body needs some time to wake up, so, when returning to what will be a light sleep for a brief period of time, you are putting your body back into a sleep mode before waking it again. At that point your body won’t know what it wants, resulting in a sort of half awaken state.

If you really want to take advantage of an alarm clock, the key is to form a healthy sleep cycle. Focus your efforts on getting enough sleep each night and waking up at the same time each day so that when your alarm goes off you feel rested.