When Sarah Hansen first came to Bonnie Schlachte's ballet studio, she jokingly called herself a “weeble-wobble,” telling her ballet teacher that when she tried to walk, she would fall. “She couldn't walk across the room without holding on to something,” recalls Schlachte. “She would immediately fall.”

    Hansen was only in middle-school, but a progressive neurological disease was hindering her ability to walk, let alone do ballet. But Hansen had a tenacious spirit and desperately wanted to learn ballet. Hansen joined in weekly group classes at Schlachte's ballet studio called Ballet for all Kids, a studio that teaches children with disabilities. Soon after she began classes and private lessons, her family saw a vast improvement in her ability to move.

    She worked tirelessly in the studio, focusing on what her instructor wanted from her. “At the time, her foot wouldn't fully rest on the floor,” explains Schlachte. “That's why she couldn't stand on her own, there was no support.”

    Schlachte pushed her student, explaining to Hansen that her brain has neuroplasticity(可塑性) so eventually it will receive the message.

    As a mom, a classically trained ballerina, and holding a degree in psychology, Bonnie Schlachte was the perfect person to push Hansen to do her best. Schlachte put herself through college with dance and theater scholarships. After graduation, she came across an opportunity with children with developmental disabilities. She fell in love and chose to focus on jobs in that field.

    Years later, Schlachte found herself watching and celebrating Hansen, who at one point could barely walk, was now moving across the floor on her own two feet. “One day, her ankle dropped, and she put her whole foot on the ground,” says Schlachte. “I was crying, her mom was crying, it was a great moment.”

    The world seems gloomy (阴沉的) and gray when you're feeling blue. In fact, being down might even affect how you perceive (感知) the colour blue. A recent study about colour was published in the journal Psychological Science. It shows a direct connection between a person's ability to perceive colour and their emotions.

    Psychologists have long known that emotions can affect the way people perceive things. That's in part because chemicals from your brain might affect how you process what you see. “Color is such an important part of our experience,” says lead author Christopher Thorstenson, a psychologist at the university of Rochester, in New York. There's reason, he says, that sad people commonly describe the world as “colourless” and “gray”, and happy people use words like “bright” and “colorful”.

    In the experiment, the researchers randomly assigned people to one of two groups. People in the sadness group watched a sad scene from The Lion King. Those in the “amusement” group watched a comedy.

    Everyone was then asked to look at red, yellow, green, and blue patches (斑点) that had been changed to a grayish colour. “Some of the patches are pretty difficulty to make out,” Thorstenson admits he says it takes some time to figure out their shade. People were scored on how accurate their colour perception was. Then they completed an emotional evaluation.

    The result? Sad people had a hard time seeing the difference between shades along the blue-yellow colour axis (色轴). But they did not have problems seeing colours in the red-green spectrum (光谱). Thorstenson says this could be the result of an evolutionary need to see red as a response to anger.

    Thorstenson says these results highlight the possible important of dopamine in sight. Dopamine is a chemical that sends signals to the brain. Researchers are hoping to focus more on dopamine in the future. “We know dopamine affects how we see colours, too,” Thorstenson says “How we feel can really influence how we see the world around us” he says.

Senses That Work Together

    When we think about how our senses work, we usually imagine them operating separately: you sniff a flower, and the smell is delivered uninterrupted from nose to brain. However, it's more complex than that. Most evidence for cross-modal perception (知觉) comes from studies into sound and vision (视觉). But research that shows other senses crossing over is coming out all the time, and it seems that even sound and smell sometimes form an unlikely pairing.

    When New York researchers, Daniel Wesson and Donald Wilson, tried to find out the truth about a “mysterious” area of the brain called the olfactory tubercle (嗅结节)，they had to deal with this fact. Originally, they only intended to measure how olfactory tubercle cells in mice responded to smell. But during testing, Wesson noticed that every time he put his coffee cup down with a clunk (哐啷声)，the mouse cells jumped in activity. In fact, the olfactory tubercle is well-placed to receive both smell and sound information from the outside world. Later they found that among separate cells, most responded to a smell but a significant number were also active when a sound was made. Some cells even behaved differently when smell and sound were presented together, by increasing or decreasing their activity.

    Of course, mice aren't people, so research team has been carrying out further experiments. They pulled together a group of people and gave them various drinks to smell. Participants were asked to sniff the drinks, and then match them to appropriate musical instruments and produce the notes at different levels. The results were interesting: piano was regularly paired with fruity fragrances; strong smells sounded like the instruments that are made of metal.

    Further research found that listening to different sounds can change your perceptions. Studying taste this time, the team ordered some special toffee (太妃糖)and put together “soundscapes” corresponding to bitterness and sweetness. Participants tasted similar pieces of toffee while listening to each soundscape, and found the toffee more bitter or sweeter, depending on which soundtrack they were listening to.

    Studies like this are helping scientists correctly describe our understanding of the senses, and how the brain combines them with its advantage. The consequences are worth considering. Could we see musicians work together with chefs to produce sound-improved food and drink? Will you be ordering a coffee with a soundtrack to bring out your favorite smell? Come to think of it, that could be one thing you hope coffee shop chains don't get round to.

    For an increasing number of students at American universities, Old is suddenly in. The reason is obvious: the graying of America means jobs, coupled with the aging of the baby-boom generation, a longer life span means that the nation's elderly population is bound to expand significantly over the next 50 years. By 2050, 25 percent of all Americans will be older than 65, up from 14 percent in 1995.The change poses profound questions for government and society, of course. But it also creates career opportunities in medicine and health professions and in law and business as well. “In addition to the doctors, we're going to need more sociologists, biologists, urban planners and specialized lawyers,” says Professor Edward Schneider of the University of Southern California's (USC) School of Gerontology（老年学）.

    Lawyers can specialize in “elder law”, which covers everything from trusts and estates to nursing-home abuse and age discrimination. Businessmen see huge opportunities in the elder market because the baby boomers, 74 million strong, are likely to be the wealthiest group of retirees in human history. “Any student who combines an expert knowledge in gerontology with, say, an MBA or law degree will have a license to print money,” one professor says.

    Margarite Santos is a 21-year-old senior at USC. She began college as a biology major but found she was “really bored with bacteria.” So she took a class in gerontology and discovered that she liked it. She says, “I did volunteer work in retirement homes and it was very satisfying.”

    Last year, when our three-year-old great-granddaughter Kylie was taken to see Santa Claus, she made sure to give him her wish list of toys. A week later, she ran into a different Santa in a mall. He stopped to ask what she wanted for Christmas. Kylie was surprised and let him know: "If you can't remember what I told you last week, how are you going to remember on Christmas Eve?!"

(Mary Paul, Milwaukee, Wisconsin)

    As my son Mike and I drove to the mall, we passed a Salvation Army Santa ringing his bell. "Mike," I said, "there's Santa!" He shook his head. "That's just some guy in a Santa suit," he said. It saddened me to think that maybe my son no longer believed in Santa, and we drove the rest of the way in silence. At the mall, we spotted another Santa greeting young believers. Suddenly, Mike took off toward him. Turning back to me, he shouted. "Now, there's the real Santa!"

(Michael E. Fahey, Huntley, Illinois)

    We immigrated to America from China when I was six. Because I was shy and didn't speak English, I had few friends. My days were spent at home with my brother. Sometimes we'd help our neighbor Mr. Mueller pull weeds. One Christmas Day, there was a knock at the door. Grandma opened it, and there stood a big fellow in red with a snow-white beard, laughing, "Ho, ho, ho!" He handed out presents and made us laugh. I had so much fun. It was years later when I learned that our special Santa was our neighbor Mr. Mueller.

(Joanne Tang, Litchfield Park, Arizona)

    Self-driving cars have been backed by the hope that they will save lives by getting involved in fewer crashes with fewer injuries and deaths than human-driven cars. But so far, most comparisons between human drivers and automated vehicles have been unfair.

    Crash statistics for human-driven cars are gathered from all sorts of driving situations, and on all types of roads. However, most of the data on self-driving cars' safety have been recorded often in good weather and on highways, where the most important tasks are staying in the car's own lane and not getting too close to the vehicle ahead. Automated cars are good at those tasks, but so are humans.

    It is true that self-driving cars don't get tired, angry, frustrated or drunk. But neither can they yet react to uncertain situations with the same skill or anticipation of an attentive human driver. Nor do they possess the foresight to avoid potential perils. They largely drive from moment to moment, rather than think ahead to possible events literally down the road.

    To a self-driving car, a bus full of people might appear quite similar to an uninhabited corn field. Indeed, deciding what action to take in an emergency is difficult for humans, but drivers have sacrificed themselves for the greater good of others. An automated system's limited understanding of the world means it will almost never evaluate (评估) a situation the same way a human would. And machines can't be programmed in advance to handle every imaginable set of events.

    Some people may argue that the promise of simply reducing the number of injuries and deaths is enough to support driverless cars. But experience from aviation (航空) shows that as new automated systems are introduced, there is often an increase in the rate of disasters.

    Therefore comparisons between humans and automated vehicles have to be performed carefully. To fairly evaluate driverless cars on how well they fulfill their promise of improved safety, it's important to ensure the data being presented actually provide a true comparison. After all, choosing to replace humans with automation has more effects than simply a one-for-one exchange.