A few years ago I caught a snippet of an interview with actress Helena Bonham Carter talking about aging. I will never forget the way she described her face transitioning from that of a round china doll to one with the angles and shadows of a wise older woman. I loved hearing a celebrity talk like this—she wasn’t ashamed of getting older like so much of mainstream media makes us think we should be. Instead, she was proud of it.

A lot of research has examined the way portrayals of older adults impact both the elderly community’s view of itself as well as the way younger adults view that population. Studies have shown that watching positive portrayals of older adults actually correlates with improved memory and reduced cardiovascular stress, not to mention a positive self-view, among older people watching such ads.

The idea is that older adults see these positive images of people in their own position and internalize that “stereotype” as being about themselves. As such, the same thing happens with negative images, only in the reverse direction. This is why so many public health campaigns are trying to steer clear of negative portrayals and ramp up positive ones.

But a new study from researchers in Hong Kong, in collaboration with Northeastern associate professor of psychology Derek Isaacowitz—himself an expert on happiness and aging—suggests a need for an ounce of caution in these kinds of depictions. Positive is good, the study suggests, but too positive can have a negative backlash.

The researchers showed that extremely positive (to the point of being unrealistic) portrayals of older adults can actually reduce memory performance, increase cardiovascular stress, and have a bad impact on self-image.

So commercials like this one, which aired at the Super Bowl in 2013, may not be all that great for campaigns attempting to promote positive outcomes among the older community:

More realistic ones like this are expected to be much more successful:

But it’s “a tricky balance,” said Isaacowitz. “It is important to have media portrayals that show both the positive as well as the negative aspects of aging. This is also helpful to younger adults to give them a better understanding of aging. On the other hand, this study suggests that unrealistically positive portrayals may have negative impacts on older adults themselves.”

Isaacowitz also cautioned that there could be some differences between older adults in various cultural settings. This study examined the Hong Kong Chinese population: “it is not clear how much of it would also translate to the U.S., but the message is suggestive,” he said.