What makes us feel better when we’ve lost someone we love?

Carolyn Simon keeps a daily planner from nearly a decade ago so she can go through old notes and appointments with her friend Holly. As she pages through it, she relives the reality of losing her best friend, but she relives her life too. Kauffman’s pipe and Simon’s planner are both what neuroscientists have dubbed linking objects, symbolic items that we hold onto after a loved one has gone.

These mementos serve different purposes throughout the grieving process, says Dr. David M Reiss, a psychiatrist with a private practice in San Diego, Calif., Boston, Mass. and New York City. In the earliest stages of grief, physical reminders of the deceased can help you acknowledge a loss, as they provided a direct connection to your loved one, reducing the trauma of loss. “At this point, a good linking object is anything that provides an emotional sense of connection with the lost one–but without engendering anger or fear,” Reiss says. “The most useful type and nature of the object really depends upon how the grieving individual processes emotions and sensations.” In later stages, as the bereaved moves toward acknowledging the loss in conjunction with the need to move on, Reiss says linking objects take on a new purpose. “The object should be able to trigger both sadness and positive feelings, feelings that do not cancel each other out, deny the loss or lead to anguish, but foster a confidence in being able to tolerate sadness and forward-looking optimism at the same time,” he says.

Choosing the objects we cling to after a loss can be more complicated than simply grabbing something, but it also doesn’t have to be. “Finding your own personal linking object to a deceased loved one is extremely personal,” says Melissa Divaris Thompson, a licensed psychotherapist from New York City. “Perhaps it’s an object such as a necklace they always used to wear. Perhaps it is a cookbook that has written on pages and spills. Perhaps it’s their favorite book of poetry or art.” The things we hold onto are as unique as the people we are trying to hold onto. And yet there’s science that plays into what we choose to keep and the means by which they connect us to those who are gone. With some objects, touch is the thing that provides the link. As University of Iowa researchers posited in a study published in PLOS One in 2014, tactile information aids memory far more than auditory information. It’s why cuddling a teddy bear from your grandmother or holding her hairbrush in your hands can send you back in time.

Items that hold a scent, meanwhile, work in conjunction with odor-evoked memory. Researchers from the Danish Aarhus University posited in a 2014 study that objects tied to one particular memory—such as your dad smoking his pipe in his chair—provide more salient cues for our memory than other objects. In another study from 2016, Brown University researchers found that smell can trigger strong, emotional memories and produce elevated activity in the brain areas strongly linked to emotion and memory. When tied to the grieving process, scents can be painful for some but extremely soothing for others. Other linking objects are not objects at all, Reiss says. They can be experiences—cooking a favored dish, listening to a favorite song, saving a voicemail message. What’s important isn’t what you hold onto, the experts say, but how it makes you feel as you navigate your grief. “The linking object should evoke a sense of happiness or nostalgia. Of course, there may be sadness also, but a linking object is usually one that relates to a good memory,” Davaris Thompson notes. “A linking object should be something that you either place somewhere you can see it or hold onto it for sentimental reasons or to pass down to someone else when the time is right,” she says. “If you want to tuck away your linking object because it makes you feel negatively (besides some sadness which is to be expected) it may not be the right item for you.”

That said, experts caution against clinging too hard to items from our loved ones. “You may want to ask yourself, why do I want this object/piece of clothing/book?” Davaris Thompson says. “Does it bring me some peace having it around? Does it serve as a nice reminder of the deceased person? When I look at it, how do I feel inside? When you can’t let go, you notice want to hold onto everything.” A good rule of thumb comes from Reiss: “A linking object should be a comforting aid that can be called on at certain times, but not the object of obsession or rigid ritual.” And if you don’t feel connected to your loved one when you pull out something you’ve saved, but you still want to keep it around, that’s OK. Linking items are personal, and as long as you get a feeling of comfort from having it around, you’ve made the right choice.