Yet despite the universality of time moving in only one direction, misperceptions abound about what it means to be various ages, driven in part by generational stereotypes and the toxic narratives—from "kids these days" to "too old to learn"—we tell one another and ourselves.

Given that the U.S. now has a historically large proportion of people over age 65—a demographic that is expected to more than double by 2050—it's more important than ever for HR to be able to separate fact from fiction about aging workers (i.e., everyone employed). Let's start with one very important fact: multigenerational workforces have been shown to be more productive and have less turnover than those without age diversity. 

Here are four myths about the generations at work, debunked.

Myth 1: Younger workers perform better than older ones.

It's true that, on average, fluid intelligence—that is, the ability for people to process information quickly—declines with age, North said. But another important aspect of brain power known as crystallized intelligence, which is based on wisdom, experience, and the ability to recognize patterns, remains stable and sometimes increases across the lifespan.

Many other key elements integral to strong performance improve with age, including conscientiousness, emotional wellbeing, agreeableness, loyalty and language complexity. "Research is finally starting to demonstrate that a lot of things get better," North said.

Other research indicates that, the more older workers are encouraged to learn by their supervisors, the more open they become to doing so. "To keep people open to new experiences, we need to make sure they feel empowered and skillful," Staudinger said.

Bottom line? "There's no overall relationship between age and job performance," North said.

Myth 2: Companies can't afford to retain Baby Boomers and other experienced workers.

This is the rationale many hiring managers will fall back on to justify excluding so-called "overqualified" candidates. In reality, however, what older workers want most isn't a huge paycheck, noted multiple experts—it's less demanding schedules. "Boomers want to stay [in jobs] longer, but they want to work on a part-time basis," said Neddy Perez, principal consultant with D&I Creative Solutions.

Myth 3: Business and HR leaders are making age diversity a high priority.

Some may be—but by and large, companies are falling short. While 64 percent of CEOs reported having diversity and inclusion initiatives in place, a mere 8 percent said they included age as part of their efforts, said Jim Link, chief human resources officer at Randstad, citing PwC research.

HR leaders contribute to age discrimination when they use "coded language" in job descriptions that correlate with younger workers. Are you looking for "recent grads" or "digital natives," for example? What about someone to "fit in with a young team," or embody youth-focused buzzwords such as "ninja" or "guru"?

Perhaps that's why studies comparing job applicants with identical resumes except for their age show that older jobseekers are 40 percent less likely to receive callbacks than equally qualified younger ones. "So much of ageism is so subtle and so socially condoned," North said.
 

Myth 4: By declining to retire, older employees are taking jobs from younger ones.

"The perception is out there that younger generations are getting screwed by older generations," North said. "From an economic standpoint, it doesn't hold true that the generations are in conflict with one another." The notion that Baby Boomers are somehow stealing jobs from Millennials is based on what economists refer to as the "lump of labor" fallacy—the idea that there is a fixed amount of work to be done in the world, so if one segment of the population does more, the others are left with less. It's fake news.

Instead, "we should be shouting to the rooftops—shouting to the heavens—it's not constructive to pit generations against each other," North said.