A study from comScore (NASDAQ:SCOR) finds that tablet use by Americans has reached “critical mass.”

In the three months ending in April, more than 23.6% of smartphone users surveyed by comScore said they had used a tablet. That was up from just 9.7% during the same time in 2011, CNET noted.

While tablets have existed in one form or another for almost a decade, the market didn’t gain any real traction with consumers until Apple (NASDAQ:AAPL) unveiled its first iPad in 2010.

Since then, tablet use has exploded. Apple alone has sold more than 50 million iPads. Other players have joined the market. Samsung and Acer produce tablets that use Google‘s (NASDAQ:GOOG) Android operation system. Internet retailer Amazon (NASDAQ:AMZN), long a producer of popular e-readers, jumped into the tablet market last year with its Kindle Fire, which allows users to stream video from Amazon’s online store.

Not all tablets have fared so well. Hewlett-Packard‘s (NYSE:HPQ) webOS-based TouchPad and Research In Motion‘s (NASDAQ:RIMM) PlayBook failed to generate significant sales.

comScore officials say the emerging tablet market will have a disruptive effect on consumer digital interaction, fundamentally altering the way people consume media, from surfing the Internet to watching TV and movies.

Most tablet users are between 25 and 54 years old, comScore noted. They also tend to have higher incomes. Perhaps not surprisingly, larger tablets also lead to more video streaming activity, compared to devices with smaller screens, including smartphones.

Smartphone ownership also appeared to be a significant predictor of a consumer’s use of tablets. comScore found that only 10.4% of owners of regular cellular phones had used a tablet this year, less than half as many as smartphone owners.