The very fact that virtual possessions don't have a physical form may actually enhance their value.
They discovered that their digital images, Facebook updates, online music collections and email threads may be as precious to them as a favorite book once read to them by a parent or a T-shirt worn at a music festival.
A fuller appreciation of the sentiments people can develop for these bits of data could be factored into technology design — and could provide opportunities for new products and services, they said.
"A digital photo is valuable because it is a photo but also because it can be shared and people can comment on it," said John Zimmerman, associate professor of human-computer interaction and design.
Jodi Forlizzi, associate professor of design and human-computer interaction, and William Odom, a Ph.D. student in HCII are working with Zimmerman on the project.
For the young people in the CMU study, a digital photo that friends have tagged, linked and annotated is more meaningful than a photo in a frame or a drawer.
Participants noted that they could display things online, such as a photograph of a boyfriend disliked by parents, which were important to their identity but could never be displayed in a bedroom.
The "placelessness" of virtual possessions stored online rather than on a computer often enhanced their value because they were always available.
The degree to which users can alter and personalize online objects also affects their value. For example, a 17-year-old study participant spent a lot of time developing an avatar for a video game and received numerous comments from friends.
The online world, in fact, allowed the teenagers to present different facets of themselves to appropriate groups of friends or to family.
Developing privacy controls and other tools for determining who gets to see what virtual possessions in which circumstances is both a need and an opportunity for technology developers, the researchers said.
The persistent archiving of virtual possessions sometimes creates real dilemmas, they observed.
If users are collectively creating these artifacts — a tagged and annotated photo, for instance - then is a consensus of the users necessary for deleting them?
"In the future, our research will explore what happens when the boundaries of virtual and physical possessions are more blurred," Forlizzi said.
"We will look at things like tags and social metadata and the role they play in sharing experiences with family members and peers."
One opportunity for technology developers, the team said, would be creating technologies that enable users to encode more metadata into their virtual possessions.
An example might be aggregating an individual's status updates, songs most listened to and perhaps even news and weather information associated with a particular event.
In some cases, virtual possessions might be given physical form.
For instance, Zimmerman said the team has explored transforming digital images of a past event, along with associated tags and annotations, into oversized postcards that could be mailed to the user.
This research was supported by the National Science Foundation and by Google.