Every kid has their own favorites. Dolls, dinosaurs, remote controls and cellphones — they might have a toy box with a wide range of play things to keep them entertained, but there's firm favorite they always reach for first-cars. Although the sex difference in the toy world remains, it's not only little boys who are drawn to all things with wheels. That my 20-month-old daughter dotes on the red bus toy is the proof of this.

From age 0 to 2, children are in the sensorimotor (感觉运动的) stage of development, explains Alyssa Wilkins. “They are learning by absorbing everything through their senses — sight, touch, taste, smell and hearing,” Wilkins says. “Toys and real-life objects like cars are very sensorily engaging. Kids can interact with toy cars, trucks, etc. through spinning (旋转) their wheels, watching them move in a variety of directions, or hearing the sounds they make.”

Plus, kids are just naturally drawn to loud and moving objects. “They see the lights on the cars and the rolling wheels, and hear the sound of the running engine. It's very engaging,” Wilkins says. “Kids will always be drawn to attractive and loud things because that is what engages their brain and sensory systems.”

Another appeal of toy vehicles is that they're typically small enough to fit in a child's hand Cars become the favorite of both boys and girls because they can put their cars in their pockets r carry them around. A car is also a cause-and-effect toy — it teaches children that their actions can make something happen. “It's super interesting and exciting for kids to learn that they can change something in their environment, and they may feel proud of what they have done,” Capanna-Hodge says.

Every child is unique in how they engage with toys, and the reasons for their play style may be diverse and complex. Ultimately, how your kids play with their toy vehicles could be a little window into what controls or excites them.

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When most of us look at our hands, we might notice that we need to clean, or stop biting our fingernails, and that’s about it. But if you ask a doctor, he can see a whole lot more. Everything from poor diet and stress to serious kidney (肾) problems can be revealed by a glance at your fingernails.

There are about 30 different nail signs that can be associated with medical issues, though may indicate more than one problem, according to Dr. Amy Derick, a clinical instructor of dermatology at Northwestern University.

Here are five of the things a doctor can tell about your health based on your fingernails.

1. People who aren’t eating well and lack vitamin or dietary may have thinner than normal nails, which are more likely to break.

2. Horizontal lines are associated with serious physical stress. They frequently occur in people who have gone through chemotherapy(化疗).They can also occur after some illnesses, injuries, or with severe malnourishment(营养不良).Interestingly, there may be an altitude connection too. They’ve also been found in people who dove 1,000 feet and others who participated in an Everest exploration.

3. Vertical lines, however, are generally not such a big deal. Some people are more genetically prone to them than others, but they’re commonly associated with aging.

4. When people lack iron, their nails can turn spoon-like. Instead of curving down and covering the finger normally, they ’ll start to rise up on the sides and front, like the part of a spoon that holds liquid.

5. Kidney and liver problems can create “half-and-half nails”, where one part of the nail is white and the other part dark or pink, according to Derick.

Doctors note that because disease diagnosis is complex and some symptoms can be associated with different diseases, you should always see a medical professional if you are concerned about something you notice.

You’ve stopped at a cafe on your way to work, and next thing you know, your latte foam is staring at you. You’ve had the same furniture for years, but today your cupboard looks sad. You’re lying in the park with your friends, and now Jesus is floating by in the clouds—are they seeing him too?!

Why do we see human faces everywhere?

Until now, it has been unclear as to why the brain processes visual signals and represents them in our mind as human faces. However, researchers from the School of Psychology at the University of Sydney have tried evaluating this phenomenon.

The facial recognition response happens fast, only taking a few hundred milliseconds. From an evolutionary perspective, the researchers suggest that the benefit of “never missing a face” outweighs(超过)the error where lifeless objects are seen as faces. Despite knowing that the object you are seeing is not a human face, the perception(知觉)of a face stays. This is known as “face pareidolia”.

Pareidolia refers to the tendency to impose a meaningful interpretation on an unclear stimulus(刺激物), making one see an object, pattern or meaning when there is none. Pareidolia was originally considered a symptom of mental disorder, but it is now viewed as a normal human tendency.

Pareidolia has been investigated by scientists and has been present in art and literature for a long period of time. In Shakespeare’s Hamlet, Hamlet demonstrates his supposed madness in his exchange with Polonius by telling him that he can see a camel in the sky.

The researchers set out to investigate whether a detected pareidolia face would be cast off as a false detection or be analysed for a facial expression. The study participants were presented series of faces and asked to rate each face expression on a scale from angry to happy. The series involved a mix of both real and pareidolia faces.

The researchers have found that pareidolia faces are not cast off as false detections, but rather undergo an internal “facial expression analysis”, in the same way a real face would. This is likely because humans are deeply social beings. Additionally, they found that biases(成见)often seen when judging human faces in the analysis of the pareidolia faces.

So, the next time that you see an angry tree, don’t be surprised and remember it’s not personal.