Studies have shown thatunlimited time-off policies attract higher-quality workers, who notonly are happier but produce better.

If they're just "talking points," perks won't do much to woo orkeep employees—but if they're meaningful to prospective or currentemployees, they can make the difference between winning/keepingtalent or losing it to another company.

That's according to the University of Pennsylvania's WhartonSchool online journal Knowledge@Wharton, which says that the rightperks, offered the right way, can strike home for job candidatesand please existing employees. But the wrong perks, offered in thewrong way, can do just the opposite—and sometimes employers fail torecognize the differences.

Related: Forget ping pong and beer taps, this is the perkemployees want

While some perks may seem frivolous and even insulting—says thearticle, "What's the use of unlimited vacation time, for instance,when employees with stipulated vacation time aren't using all of itnow? And don't workers who haven't seen real wage growth over thepast decade look upon company-provided yoga lessons or a newping-pong table with a jaundiced eye?"—others can really make thedifference.

According to Wharton management professor Sigal Barsade, a perkthat's "tied to the values of the company, … a living instantiationof the culture, then it can have deep symbolic meaning." Barsadepoints toward bereavement days for a pet's death as an example,which can be "a great representation of a culture of companionatelove—that is, affection, caring and compassion," and possibly veryrepresentative of a company's emotional culture.

Candidates may not be aware of the stakes behind such perks, butaccording to the report, the top one percent of talent at a companycan be responsible for 15 to 20 percent of "value-added,"which means that a company will go pretty far to bring in that toptalent. But the wrong gesture can be seen as a sop, rather thansomething that's actually meaningful in terms of improving theemployee's life.

Although most employees surveyed say the perk they'd most likeis unlimited paid time off, employees themselves often fail torealize the reality that they probably don't use all the paid timeoff they already get. Yet studies have shown that such a policyactually does attract higher-quality workers, who not only arehappier but produce better.

Still, companies have to beware sending the wrong message withperks on offer, since Barsade points out that "if you sense you arebeing coerced into staying at work longer and don't want to dothat, then having all these things on site may well be viewednegatively."

Companies should be asking employees directly in surveys andfocus groups how they feel about what they're offered, and notrelying on anecdotal evidence—particularly since they can beexerting other pressures, subtle and otherwise, on employees bysitting on pay increases, freezing benefits and bringing in gigworkers—tactics that could negate any benefit they might otherwisederive from offering people perks by delivering an underlyingmessage of not caring about, rather than valuing, the people whowork for them.

Read more: 

• 4 perks to make your employees' lives easier andless stressful
• Millennials would choose dogs in the office overother benefits, perks
• Benefits can be more important than cash forsmall-business employees