Have Facebook, Twitter reached saturation?

While Facebook and Twitter have a dedicated user base that constantly use the social networking sites, they fail to attract more new users, according to a new survey.

In contrast, Pinterest and Instagram continue to attract new users, a recent Pew Research Centre study found.

The proportion of online adults who use either Pinterest or Instagram has doubled in three years, it found.

Now, 31 percent of people use Pinterest (up from 15 percent in 2012), while 28 percent use Instagram (up from 13 percent in 2012).

However, Facebook remains the most popular social media site, especially among women, with 72 percent of online adults using the service. Most use the social network daily, more than any other platform, PC Magazine reported.

Although LinkedIn saw a decline in usage over the last three years, the professional network still attracts people to its site, with 22 percent of respondents visiting daily, the report said.

"The results in this report reflect the noteworthy and rapid emergence of different kinds of communications tools serving different social needs," the study said.