We have this impression that our memory is like a collection of video clips. This construct—which includes the impression that memory is static—is convenient but inaccurate.

When we have a blank in our memory the brain tends to backfill—it extrapolates or interpolates and fills in the missing information. Memory is a reconstructive process, not a perfect recording.

When we “remember” an event, we’re actually stitching together fragments of information. This process is guided by our general knowledge, expectations and inferences. We use this process to create a coherent (if not photographically accurate) “memory.”

The data available to the brain is imperfect. When aspects of an event are missing or faded the brain fills in the gaps. When there are inconsistencies, the brain reconciles “memories”.

When preparing people for depositions I give them three rules. One of the rules is: If you don’t know, can’t remember or aren’t sure, say exactly that. But that’s really hard to do when the brain is programed to backfill details that we haven’t captured, can’t retrieve or aren’t sure about.

The brain’s compilation of data into memories is pretty similar to the predictive features on electronic devices.

The brain utilizes prior knowledge and familiar patterns to supplement recorded information with additional information that fits logically within a recognized framework. If an image of a flag is stored in the brain but the data packet is missing a flag pole, the brain will supply the flagpole to ensure the memory makes sense.

This reconstructive process allows us to "remember" events as coherent and complete stories even if our stored data is incomplete. It also means our recall of events is susceptible to distortion. There’s the possibility of forming a partially or entirely false memory.

The brain doesn't just retrieve memories; it actively reconstructs them. That’s one of the reason why two people can remember the same event so differently. It’s also why mis-remembering something does not mean that someone is being untruthful.

Once you understand how memory works, it’s a lot easier to deal with the natural differences we have in the way we remember an event. It also reduces the temptation to accuse people who remember events differently than we do of lying about them