NEW YORK: Social networks occupy a growing amount of US online usage time and play an increasingly important role in shaping purchase habits, a study has found.

NM Incite, a joint venture between Nielsen and McKinsey, reported social networks and blogs accounted for 22.5% of Americans' internet activity during May 2011, well ahead of gaming in second place on 9.8%.

Facebook received 140.3m unique visitors across the month, with women making up a majority (62%) of the site's overall page views.

Blogger attracted 50.1m people, a figure standing at 23.6m for Twitter. Tumblr, another blogging platform, saw its user base increase to 11.9m, an improvement of 183% since May 2010.

In keeping with its huge penetration, Facebook registered the highest aggregate dwell time, on 53.5bn minutes, beating Yahoo's 17.2bn and Google's 12.5bn.

Of the social media audience, 97% logged on to the sites via a PC, 37% used a mobile phone, 3% an iPad and 2% an ereader, NM Incite added.

Overall, the total mobile social media population had expanded by 62% annually in May. Facebook again led here as 46.5m people accessed its pages from a handset, with Twitter on 11.5m and LinkedIn on 6m.

Elsewhere, 17.8 women streamed video through social networks in the same month, watching 73.8m clips for 227m minutes. Only 14.6m men engaged in this pastime, but they played back 83m items of content for 248m minutes.

Additionally, the study revealed 53% of active social network users follow a brand. Some 82% of female netizens also shared their opinions about products they liked via digital channels, versus 72% of men.

When citing their preferred source of information concerning products, 63% of the same demographic chose consumer ratings and 62% opted for user reviews. Facebook pages secured 15% on this measure, and Twitter feeds recorded 7%.

A further 61%, of this group wrote reviews of goods and services to "recognise a job well done". However, 58% were seeking to "protect others" from bad experiences and 41% hoped to receive vouchers and discounts.

Exactly 32% wanted to connect with a company, 31% enjoyed "feeling empowered" and 25% intended to "punish" a brand owner.

In all, 60% of people researching goods and services via multiple online sources learned about brands on social sites. A similar proportion of 16-34 year olds were keen to recommend improvements, and customise, products.

Data sourced from NM Incite; additional content by Warc staff