Recognition memory

Imagine taking a seat on a crowded bus. You look to your left and notice a man. Immediately, you are overcome with this sense that you've seen this man before, but you cannot remember who he is. This automatically elicited feeling is familiarity. While trying to remember who this man is, you begin retrieving specific details about your previous encounter. For example, you might remember that this man handed you a fine chop of meat in the grocery store. Or perhaps you remember him wearing an apron. This search process is recollection.

The question of whether recollection and familiarity exist as two independent categories or along a continuum may ultimately be irrelevant; the bottom line is that the recollection-familiarity distinction has been extremely useful in understanding how recognition memory works.

Participants are asked to identify which of several items (two to four) is correct. One of the presented items is the target—a previously presented item. The other items are similar, and act as distractors. This allows the experimenter a degree of manipulation and control in item similarity or item resemblance. This helps provide a better understanding of retrieval, and what kinds of existing knowledge people use to decide based on memory.

When response time is recorded (in milliseconds or seconds), a faster speed is thought to reflect a simpler process, whereas slower times reflect more complex physiological processes.

On the whole, research concerning the neural substrates of familiarity and recollection demonstrates that these processes typically involve different brain regions, thereby supporting a dual-process theory of recognition memory. However, due to the complexity and inherent interconnectivity of the neural networks of the brain, and given the close proximity of regions involved in familiarity to regions involved in recollection, it is difficult to pinpoint the structures that are specifically related to recollection or to familiarity. What is known at present is that most of a number of neuroanatomical regions involved in recognition memory are primarily associated with one subcomponent over the other.