These findings, published in Psychological Science, a journal of the Association for Psychological Science, suggest that older adults retain the ability to make accurate judgments about others' emotions using their acquired knowledge, but not sensory cues.

"When judging others' emotions in real life, people do not exclusively rely on emotional expressions," says lead researcher Antje Rauers of the Max Planck Institute for Human Development in Germany. "Instead, they use additional information, such as accumulated knowledge about a given situation and a particular person."

To investigate how these two processes vary with age, Rauers and colleagues Elisabeth Blanke and Michaela Riediger recruited 100 couples, some of whom were between the ages of 20 and 30 and some of whom were between the ages of 69 and 80. When they came to the lab, Rauer and colleagues first showed various faces to the participants, asking them to identify particular emotions.

"We started by replicating past research, showing that older adults are typically worse than younger adults at interpreting emotions through facial expressions," Rauers explains.

Then the researchers took the study outside the lab, asking participants to record their own emotions and the emotions of their partners six times a day for two weeks using a cell phone.

When the participant's partner was nearby, the participant could use his or her partner's facial expressions as an indicator of their emotions. But it was those moments when the partner was absent, which occur frequently in everyday life, that the researchers were particularly interested in.

Even though partners were sometimes in different places, they recorded their emotions at the exact same times throughout the day. This way, the researchers could tell if one partner was accurately estimating how the other partner felt at that particular moment.

The data revealed that older adults were not as adept as younger adults at reading the expressions in their partner's face -- when both partners were present, the older adults estimated consistently worse than their younger counterparts. These findings confirmed the results from the expression recognition task completed in the lab.

But the age differences disappeared when the researchers looked at only those moments when the partners were separated. In these cases, both older adults and younger adults were equally good at estimating how their partner was feeling at a given moment.

These findings suggest that some cognitive processes associated with understanding and empathizing with one's partner remain stable as we age.

"Reading emotional expressions may become more difficult with age, but using one's knowledge about a familiar person remains a reliable strategy throughout adulthood," Rauers concludes.

"This is really good news, given that the overwhelming majority of research findings testifies an age-related decline in many competencies," says Rauers. "Our data suggest that knowing your loved ones well is an important resource that stays available throughout life."