Memory

Every aspect of daily behavior even ones as automatic as knowing who we are and where we live is guided by memories of past experiences. Research scientists have distinguished three phases of memory. First, registering or encoding an event into a memory trace; next, storing and retaining it over a period of time; and finally, retrieving and using it to guide actions. Memory for a particular episode may fail due to errors in any of these three phases. Research is also uncovering many types of memory, each with distinctive characteristics and functions.

To study memory in humans, researchers have devised simple laboratory tasks that permit memory reports to be compared with what actually happened. Subjects may be asked to study a list of words or view a set of pictures or novel shapes; in some cases, they may be presented with more complex material, such as a written narrative, a staged episode, or a film clip. Although such situations seem far removed from everyday remembering, this research has yielded surprising insights into how memory works.

Reconstructive Memory

One important discovery is that remembering is not just a matter of reproducing a copy of what happened in the past. In important respects, people actively reconstruct representations of events based on fragmentary information stored in memory as well as their inferences about what probably occurred. For this reason, human memory is often not completely reliable. People frequently confuse what happened at one time with what happened at another, or they mix together parts of several memories. When their memories are vague, they fill in the gaps with what they believe to be probably true, often without awareness of their guesswork. The tendency to edit and embellish what we recall seems to be a natural outcome of the way human memory works.

Considerable research shows that knowledge acquired after an event often becomes incorporated into memory for that event. In a typical study, subjects first witness a complex event, such as a simulated crime or an automobile accident. Then half of the participants receive new and misleading information about the event, often subtly disguised in questions they are asked about it. The other participants receive no such misinformation. When the subjects recall the original event, those given the misleading information reveal distorted memories. This effect has been confirmed in many studies. People have recalled nonexistent broken glass and tape recorders, a clean-shaven man as having a moustache, straight hair as curly, and even a large barn in a rural scene that had no buildings at all.

Going beyond demonstration studies, more than a decade of research has revealed the conditions when people are particularly susceptible to postevent misinformation. Memories are especially prone to modification when the passage of time allows the original memory to fade and when the misinformation is subtle and comes from a credible source.