Fully 53% of households participate in media multitasking while the TV is on each week, according to the report, rising to 56% for women compared with 51% for men. Respondents with children at home also registered 66% here.
Exactly 25% of the sample had taken to "media meshing" - activities on other devices related to the content they are viewing on TV.
These figures hit 74% and 44% in turn for young consumers. Among the most popular "meshing" activities for panel as a whole were texting on 17%, speaking on the phone with 16% and using social media on 11%.
An additional 49% of people pursue "media stacking" - or undertaking unrelated tasks on tablets and smartphones alongside viewing TV programmes - per week.
On average, consumers watched 241 minutes of TV every day, a total 15 minutes higher than in 2008, although the number of homes with only one TV set has risen from 35% in 2002 to 41% in 2013.
Despite this, the proportion of adults enjoying broadcast content on the main set each week has grown from 88% to 91% in the same period.
"Our research shows that, increasingly, families are gathering in the living room to watch TV just as they were in the 1950s - but now delivered on bigger, wider and more sophisticated sets," James Thickett, Ofcom's director of research, said.
"Unlike the 1950s family, however, they are also doing their own thing. They are tweeting about a TV show, surfing the net or watching different content altogether on a tablet."
The report also found that the typical British household currently contains three types of internet-connected device, and one in five homes has a minimum of six such gadgets.
One driver of this process is that smartphone penetration has grown to 51% of households from 27% two years' ago. Tablets, too, have witnessed impressive growth from 11% to 24% in the last 12 months
Some 9% of households own at least two tablets, and half of owners "could not live without" these devices, up from 34% last year. A third of users agree this is the main way they connect to the web.
Data sourced from Ofcom; additional content by Warc staff