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Haven't I seen you somewhere before? Although this may be a lousy pick-up line, it reflects a common state of memory. You see someone who looks familiar. You can't, however, remember who that person is, where you met, or anything else about the person.
This memory problem happens to me relatively frequently. I've lived in the same community for a long time and I've met a lot of people. As I wrote in a recent post, I work hard at remembering names and have developed some skills and tricks (see Remembering Names: Secrets of Memory Experts). Nonetheless, my memory can fail at critical moments. I see someone in the grocery store and the person looks familiar. Desperately, I search my memory: Is the person a student, a former student, a friend of a friend, someone I've met through my sons? Sometimes when that person turns, we share a moment of panic: We recognize each other, but can't remember each other's name and have no idea of how we met. An awkward head nod follows as we smile and pass. Each of us is secretly relieved that the other person also failed to remember.
In contrast, I enjoy the moments when I recognize a student someplace off campus. When I see students I know in the grocery store, for example, I happily greet them by name. Sometimes I can see that they are experiencing the memory failure - they know I am familiar, but they have difficulty remembering who I am. Usually they get the "ah-ha" expression and remember me pretty quickly. Of course, it's much less fun when a student greets me and I'm the clueless one. I smile awkwardly, say hi, and try recall what class that person took with me.
This memory failure reflects two important aspects of how memory works. First it reflects a distinction between item activation and source memory. Item activation leads to that feeling of familiarity. Activation of a piece of information also includes saying "George Washington" in response to the question of who is on the one-dollar bill. On the other hand, source memory is remembering something about the occasion when that knowledge was previously encountered or used. For example, source memory would be remembering when you learned that the guy in the wig on a one-dollar bill is George Washington or remembering the last time you folded a dollar bill so that GW looked like a mushroom. Source memory is remembering a particular time and place. Familiarity versus source memory is the distinction between remembering the gossip you recently heard and forgetting who divulged the juicy nugget.
Unfortunately source memory both fades rapidly and is difficult to retrieve. Thus for a wide variety of things we can experience a feeling of familiarity in the absence of source information. This can lead to a great variety of memory and judgment problems: Such as seeing someone who looks familiar, but remembering no source information about previous encounters. I suspect this is particularly likely to occur with remembering people because humans are so good at recognizing faces and so poor at remembering names.
A second important aspect of memory also contributes to seeing someone who looks familiar and failing to remember who the person is. Remembering depends on whether the retrieval context matches the encoding context. For example, my students and I easily recognize each other in the classroom - the context where we first met and continue to interact. We can generally succeed if we see each other wandering across campus. There is a basic overlap of the retrieval and encoding contexts that will enable remembering. When we encounter each other off campus, however, remembering is more difficult. In this very different context, some level of familiarity may be experienced, but at least one of us frequently experiences difficulty remembering much else.
Thus a feeling of familiarity without recollection highlights crucial features of memory. From all experiences, we create a feeling of familiarity and memory for contextual details. Without a good match between the original learning context and the retrieval context, much of the detailed source memory information may not be remembered. Sometimes, trying to think about where and how I might have met someone will aid in remembering who the person is. When that fails, however, I am left smiling and making the awkward head nod, or using that bad pick-up line.
