【推荐1】Scott Edwards stopped his cross-country bike trip when he found a red-headed woodpecker (啄木鸟). “I got my first good look today,” he says. He was phoning from his tent in Illinois later that night. “I hadn’t seen the red head until today, so I was very excited.”

Edwards is a bird researcher at Harvard University in Cambridge, Mass. Over this past summer, he rode across the United States. In some degree, he did it to see the country. But he also used the trip to do some serious bird-watching. That’s something he’s been doing for more than 40 years.

When he was growing up in the Riverdale neighborhood of the Bronx in New York City, there were lots of trees, he recalls (回想). When he was nine or ten, a neighbor took him bird-watching. Edwards has been doing it ever since. But finding those birds is getting more difficult. “The numbers of birds are dying down,” he says. And Edwards is hardly the only one to notice it. Scientists around the world have been finding the same thing.

A 2018 study by Bird Life International found that birds around the world are in trouble. There are about 11,000 species of birds. Four in every ten species of them are decreasing in number. That’s true for all kinds of birds living in all types of habitats (栖息地). Only a few members of these species remain in the wild. And even common birds are less common than they were just 50 years ago. What’s worse, that’s now true almost everywhere.

【推荐1】Would you rather watch a new movie or an old favorite? Would you rather try a dish, you have never had at a restaurant, or stick with something you know you will like? Researchers studying the “mere-exposure effect”(曝光效应) have found that we often prefer the familiar over the novel.

In 1968, social psychologist Robert Zajonc published a landmark paper on the mere-exposure effect. His hypothesis (假说) was that simply being exposed to an object on a repeated basis was enough to make people like that thing. To test this, Zajonc had participants read words in a foreign language out loud. He varied how often they read each word (up to 25 repetitions). Next, participants were asked to decide how positive or negative the meaning of each word was. Zajonc found that participants liked the words that they had said more often, and the words that had been read 25 times were rated the highest.

In the decades since Zajonc published his paper on the mere-exposure effect, researchers have also suggested several theories to explain why the effect happens. One of the leading theories is that mere exposure makes us feel less uncertain. According to this idea, we tend to be cautious around new things, since they could be dangerous to us. However, when we see the same thing over and over and nothing bad happens, we start to realize that there is nothing to be afraid of. Additionally, mere exposure increases what psychologists call “perceptual fluency” (知觉流畅性). It is based on the idea that, when we have seen something before, it is easier for us to understand and interpret it, which puts us in a positive mood.

While psychologists are still debating what causes the mere-exposure effect, it seems that having been previously exposed to something can change how we feel about it. And it may explain why, at least sometimes, we tend to prefer things that are already familiar to us.

【推荐2】The idea that red means stop and green means go affects more than just traffic light colors. We have been taught from a young age that red means danger, while green means safety.     1    For something we have to look at every day, why couldn’t they have been prettier colors? You’re about to find out.

Before there were traffic lights for cars, there were traffic signals for trains. At first, railroad companies used red to mean stop, white to mean go and green to mean caution. But train conductors ran into a problem with the color white meaning go — bright white could easily be mistaken for stars at night.     2     It has been that way ever since.

    3     That means that as it travels through the air, it gets diffused (分散) less than other colors, so it can be seen from a greater distance. For example, think about how the light turns red as the sun sets. Even though the human eye is most sensitive to a yellowish-green highlighter color, it can see red from further away. But this could happen by chance. It’s not clear whether that was chosen based on wavelength, contrast against green nature or natural connection of red with things like blood.     4    

Yellow has a shorter wavelength than red but a longer wavelength than green. This means that red is noticeable the furthest away, yellow in the middle and green the least distance away — a helpful advanced warning for needing to slow or stop.

However, believe it or not, yellow was once used to mean stop. Back in the 1900s, some stop signs were yellow because it was too hard to see a red sign in a poorly lit area.     5     Since yellow can be seen well at all times of the day, school areas, some traffic signs and school buses continue to be painted the color. Keep these safe driving tips in the back of your mind whenever you see a yellow light.

【推荐3】Regularly practicing facial “yoga”, or exercises for your facial muscles, may actually make you look younger, early research suggests，

In a small, new study, researchers taught 27 middle-age women (ages 40 to 65) how to perform 32 facial exercises, which included simple actions such as smiling in the cheeks. After this training, the participants performed these exercises at home for 30 minutes a day, every day for eight weeks. On the ninth week of the study, the participants reduced the frequency of their 30-minute exercise routine to every other day (three to four days a week), and continued the exercise for 20 weeks.

The participants also had their photos taken at the beginning and end of the study, and several doctors rated these photos using a standard method for assessing the appearance of aging in the face and neck. The raters, who didn’t know which photos were taken before and which photos were taken after the exercises, also estimated the age of the person in the photo.

After 20 weeks, the participants had better ratings for the fullness of their cheeks, on average, compared with their ratings at the start of the study. In other words, their cheeks looked fuller after their 20-week facial exercise. This change in cheek fullness also made the participants look younger: Raters estimated that the participants looked nearly three years younger after the exercises, compared with before.

However, the findings are preliminary and should be confirmed with a larger study, the researchers said. And many questions remain about exactly which exercises are beneficial and who might benefit from them. “The study involved middle-age, mainly white women, who stayed in the study for 20 weeks, so it’s not known whether the effects seen in the study would apply to men, or to people of other ages or races. It’s also not clear how long people need to perform the exercises in order to see benefits,” lead study author Dr. Murad Alam said.

【推荐2】Have you ever had the same experience? While watching late-night TV, an advertisement comes on for something that looks very tasty. Maybe it’s a delicious pizza, an icy beer, or a juicy steak. We think “how I wish I could get my hands on that right now”

Our wish will come true soon. A Japanese professor has developed a lickable TV screen that can imitate food flavors you can experience with your own mouth. The invention is called Taste the TV (TTTV). Though it’s just a model right now, its inventor, Meiji University professor Homei Miyashita, believes it could be produced in large numbers in the near future.

“The goal is to make a platform where tastes from all over the world can be tasted by users even while staying at home. It’s the same as watching a movie or listening to a song that you like,” Miyashita adds. “I hope people can, in the future, download and enjoy the flavors of the food from the restaurants they like, regardless of where they are based.”

In a video demonstrating how TTTV works, tastes are sprayed(喷) onto a rolling sheet of plastic, which then goes over a video screen. To create the tastes, a series of 10 containers, each with a chemical substance inside it, work together much like the red, yellow, cyan, and black inks in a printer to make up all of the colors you can put onto a sheet of paper. And like the printer, the containers will need to be refilled sometimes. But the video screen doesn’t need to be the lickable ingredient. The same tastes can be sprayed onto any other single-use plastic. The video also shows other ways TTTV could be used.

Meiji University student Yuki Hou, 22, got a taste of it. She told the machine that she wanted to taste sweet chocolate, after which the flavor containers sprayed a sample onto the plastic sheet on the screen. “It’s kind of like milk chocolate,” Hou said with a big smile, after licking the screen. “It’s sweet like a chocolate sauce.”