Last month I wrote a feature about foreign high school students who will be living with local Shanghai families for a year on a study-abroad program ("Shanghai's own modern families" published on September 21).

Two of the participants I interviewed just after their arrival in China, expressed their optimism about living in Shanghai, saying that their Chinese teachers and classmates had been friendly and their host families hospitable.

To my dismay, though, after being invited by the program to do a follow-up story, the participants' optimism and enthusiasm had been replaced with disappointment.

The two 16-year-olds, from Norway and Germany, complained that it had become difficult for them to make local friends here. "Our classmates were friendly toward us only during the first couple of weeks," they told me. "But now, after the novelty of our presence has worn off, they just give us the cold shoulder."

It is quite common for newly arrived Westerners in a foreign country to expect to expand their social circles and befriend locals, but in China, many often find that, despite the initial affability of the Chinese, few locals are in fact less willing to become true friends with foreigners.

"Few of my classmates like to talk with me," said the German boy. "When I invite them to hang out or go shopping on weekends, they reject me by saying that they have no time. Do they dislike me? Have I done something wrong that made them unhappy?"

Theirs is not a solitary case. Zhang Yiyan, who works with the AFS Intercultural Programs organized by the International Education Association Shanghai, said that every year at least a few of the participants will feel some frustration and self-condemnation after being cast off by their Chinese peers. "They think that it's their fault for failing to make friends here, so they become unconfident and full of self-doubt," she sighed.

Cultural differences between Chinese and Western youngsters extend well beyond the highly publicized contrasts and comparisons in their study habits. In fact, the differences in sociability and interpersonal relationships might be one of the largest yet least-addressed gulfs between East and West.

Many Western students, for instance, tend to believe that engaging in social activities such as "hanging out" or playing sports with another youngster makes them buddies. Chinese students, however, tend to regard as their friends only those who do homework or prepare for exams together.

Moreover, Chinese and Westerners have very different approaches to finding friends. In most Western countries it is quite common to see complete strangers engage in conversation, especially at bars and events, often culminating in exchanging phone numbers or social media information.

Western-style "chatting up" doesn't work in China. Strangers are met with suspicion here, and Chinese prefer to socialize only in their immediate circles rather than go to venues to converse with people they don't know. "Chinese seldom go to pubs or clubs, let alone chat with a strange foreigner who suddenly come and say hi," Zhang confirmed.

Growing up in one-child families in an Internet-obsessed era, most Chinese students are sheltered and often lead withdrawn childhoods. Many are neither good at nor fond of socializing in real life and remain satisfied with keeping people at a distance.

Instead, Chinese youngsters prefer to chat online with people who share common interests, such as gaming or pop idols, without ever feeling the desire to get to know the person behind the avatar.

When it comes to making friends with foreigners, however, language is often the most obvious cause that holds back Chinese students. The Norwegian girl I interviewed said that she was surprised that, even though her 12-year-old host sister has excellent written grammar in English, she could not apply any of her learned language skills to actual use. "I found that she could not speak even simple English to me," she said.

Indeed, the average Chinese student can pass their written English exams with ease, but usually do very poorly when it comes to putting the language into practical use. My cousin received an impressive 135 out of 150 on her gaokao (China's national college entrance exam) English test, but her oral English is stuck at a kindergarten level.

Taking all these cultural differences into account, there's no need for the program's foreign participants to be frustrated with failing to make Chinese friends. Nor should they take it personally when a Chinese student rebuffs their friendly overtures.

But as far as making friends with locals, they'll need to be the ones to adapt. "If these kids are unable to make adjustments," said Zhang, "their days in Shanghai might turn into a real hard time."