About one-third of men, (32 percent) used the business-networking site vs. 15 percent of women. The more social Facebook attracted 74 percent of women vs. 59 percent of men.

To Barker, who studies and conducts research on social media use, the split found in the online survey – which was conducted in February and March of 2,081 defined contribution plan participants – just makes sense.

"Women predominate in Facebook (in general)," she said. "Men overwhelmingly predominate in LinkedIn. This is because women are more likely to use Facebook for purposes of connection and communication. … By contrast, males are more likely to use social networking for information dissemination and learning."

The survey found that 71 percent of retirement plan participants "routinely" use one or more social media sites. However, the percentage of participants that have used social media for information or advice about their workplace plan has grown from 5 percent to 6 percent since 2011. While the number overall is small, it equates to approximately 5 million participants who have used social media for this purpose, indicating that it is used to supplement rather than replace the participant's primary retirement plan website.

"This (finding) may represent an important window of opportunity to reach these participants at a critical time in their retirement savings lifecycle," said Elaine Sarsynski, executive vice president of MassMutual's Retirement Services Division.

In addition, those who are contributing to their retirement plans are more likely to seek information about their accounts on social media, the survey found. Those saving outside of the workplace were more likely to use Twitter, LinkedIn and Facebook, in that order. Household income was also a factor in social media use. Of those making above $100,00, 36 percent used social media sites. The percentage of social media users in households making $50,000 or less dropped to 15 percent.

And while social media usage is up across the board since 2011, LinkedIn saw the biggest increase in usage, at 24 percent, which is a 50 percent increase, said Merl Baker, principal at Brightwork Partners.

So what should retirement advisors do?  

"Facebook has broad appeal across all age groups but clearly there is an opportunity for providers to target messaging by gender, age and income," Baker said.

In other words, it's probably best to use all of the big three, Facebook, LinkedIn and Twitter.

Elsewhere, the survey also showed that retirement tops the list of savings objectives. Overall, "saving enough for retirement" has surpassed "keeping up with monthly expenses" as the biggest financial worry, up significantly to 24 percent from 18 percent in 2011.

It was also cited as a major savings objective by 63 percent of participants, 21 points higher than the second most-cited worry of "paying down debt."

On a positive note, participants in general are saving more, with the average retirement savings rate among those surveyed at 10.5 percent, up from 9 percent two years ago, showing an increased commitment to this goal.

In any case, finding the sweet spot for using social media to reach participants of both genders will take more than knowing which prefers which.

"I believe that successful design of social media platforms involves providing a mixed landscape of information and interaction," Barker said.

Elaborating, she cited research at San Diego State as providing evidence underscoring the need to allow users to interact with each other to form a community, no matter how weak their ties.

"This may be especially important to women," she said. "(And) although men may be primarily online to obtain information, they may also wish to learn about the experiences of online others for utilitarian reasons – hence the value of an interactive environment."

Also read:

5 Web tools brokers need
4 social media tools brokers need to use
OMG! The benefits of technology