There are several theories about how we create memories and how we use those memories to interact with our worlds. Take a restaurant as an example. When you think of a restaurant, a fairly specific memory is used to represent restaurants in general. Now think of a fast food restaurant. The image changes. One theory of cognition is that we create lists that represent different interactions. For example, we have a script for restaurants so we know what to expect when we go to one. We enter, wait to be seated, order, eat, pay, leave. The script is modified to account for different types of restaurants. in the fast food example, waiting to be seated won’t work. So, we create a new list to account for it. In that list, we enter, order, pay, eat, leave. The other theory of cognition is that we store elements of previous encounters and use those to assemble an appropriate mental picture that we can apply to a specific situation.
The way we recall events and integrate them into our minds isn’t as simple as recording them. The analogues to memory that we have created, hard drives, web sites, etc. record events in a linear way. Human memory doesn’t record events in the same way. Instead of remembering an event like a wedding one instant at a time, we record a representation of the event that we can later recall. This method of remembering can alter the event in our minds in interesting ways. Each element of an event is stored in different parts of the brain and then reassembled when we recall it. Each time we remember a wedding, the mind assembles the different parts together to create a new representation of the event. In essence, we’re recreating the event each time we remember it.
For the wedding example, the ceremony is broken into different elements. The visuals sounds, smells, and tactile memories are compiled together from different areas of memory to create the memory that we then recall. The way that the elements are stored allows the mind to free associate those parts with other memories that can then impact the recollection of the whole. When you recall a wedding, the smell of the flowers can be influenced by other memories that include smells. A trip to an arboretum can influence the wedding memory in subtle ways. Discrete elements of the arboretum won’t intrude on the wedding memory, the mind would recognize those parts as being out of place in the wedding memory. Instead, the sensations and smells of the arboretum can influence the recollection of the wedding. When the mind assembles the wedding memory, it pulls the smells from the same area that stores the smell memories of the arboretum. In doing so, the two memory fragments influence each other. The memory of the arboretum would likewise be influenced by memory fragments from a wedding.
When the mind assembles a memory, it has to free associate within each part of the memory to assemble to whole. Each sense, smell, touch, sight, sounds, and taste has its own area. As the mind recalls each sense, other memory fragments can influence how we recall each element of the whole. This is one of the reasons why eye witness testimony can be problematic. When the witness tries to assemble the memory of an event, other experiences can influence how that memory is assembled. Since the mind essentially creates the memory each time it is recalled, that recollection can drift over time. As other experiences change the memory, a discrete memory can start to change the more we recall it. That’s why police want to get eye witness testimony when it’s “fresh” and people say that the first impression is usually the right one. It’s not necessarily true, but it does leave the memory less time to be affected by other experiences and memory fragments.
The list and fragment theories of memory aren’t exclusive to each other. We could use memory fragments to create the lists dynamically. The list theory is tempting because that is the way it feels when we go to a place like a restaurant. We create a script that we expect to follow throughout the whole episode. How we create the list may be more interesting than the list itself. In many ways, every memory is the culmination of all our experiences.