Our memories of events are a kind of 'database of the self'. This store of recollections plays a key part in our identity, and is termed 'autobiographical memory'.
Some psychologists (e.g. Conway and Pleydell-Pearce) believe that we tend to remember events from our lives better if they have a good fit with our goals and objectives. For instance, we may have a good recollection of receiving news of passing an important exam, or of any event which we see as helping us to achieve key objectives.
In later life we tend to forget most, if not all, events up to five years old - known as 'childhood amnesia'. Nobody knows exactly why - it is surprising, because most under-fives do have good capacity to have the memories in the first place. Conway and Pleydell-Pearce believe that we forget all this as adults because our adult goals are not the same as when we memorized the original events. As an alternative, a Freudian view might suggest that, as adults, we 'filter out' childhood memories as too uncontrolled and powerful.
In contrast, we do seem to have a preference for remembering events from our late adolescence and into our early twenties. This is called the 'reminiscence bump' (RB). Memories from this period are unusually accurate. Our preference for these memories is not because they are more vivid or pleasant, nor because the memories are first-time memories. It seems to be because our life stabilizes at that time, and because it is a self-defining period.
We have a slight preference for recalling recent events, probably for the obvious reason that they haven't drifted far enough into the past to slip too much from our minds!
HOW THE DATABASE WORKS
Conway and Pleydell-Pearce have modelled how all this might work.
1. First of all, we have 'sensory-perceptual memories' - memories for particular events which have not been 'filed' away in our minds very efficiently. A bit like a photograph sitting on the table, but without any label on it for future reference.
2. Then, over time, these snapshots get labelled as 'general events' with more abstract labels - for instance, we may label them in our brains according to our emotional state at the time, or how well the event helped us achieve our objectives.
3. Finally,we may abstract even further into 'lifetime periods', which may relate to overall life goals. These 'lifetime periods' can form part of a 'life story' - an account of ourselves which link everything together to form a theme or themes.
We can filter from 3 to 2 to 1 above. When we remember events, we may start with a lifetime period, narrow things down to a subset of general events, and then focus in on a sensory-perceptual memory. Psychologists Haque and Conway have found that this is indeed how we tend to retrieve past memories - narrowing down our search from a wide initial base.
EVENTS AND GENERAL KNOWLEDGE
A remembered episode is a kind of 'recollection' - some psychologists think this recollective kind of memory is different from general knowledge, which is known more as 'semantic' menory, and consists more of detached facts rather than events. Psychologist Conway suggests that most sensory-perceptual memories (i.e. particular events) are lost to memory, unless they are linked strongly to some kind of general event or personal goal at the time of memorizing. When we later recall incidents, we tend to recreate the emotional state we were in at the time.
There is strong evidence for goal-bias in memory. For example, cognitive psychologist McLelland split people into intimacy and power types, and found that their personal memories tended to have a flavour of either power or intimacy, depending on preference. Another researcher, Woike, split people into independent and nurturing, and found similar biases. This is not surprising, when you think that your nature will define your preferences, and your identity define your goals - in other words, if you are a power-crazy loner, then a nurturing family gathering last year may not feature in your memories as much as winning a million pounds for yourself! Personal goals can compensate for childhood disappointments - for example, someone who did not get intimacy in childhood, may, when they are grown up, look for relationships where extreme intimacy occurs.
POST-TRAUMATIC STRESS DISORDER
Stressful events can trigger a special type of memory, which returns even if we do not want it. Memories are disruptive and intrusive, and tend to recreate feelings of intense threat, fear, horror or hopelessness. We may get sensory-perceptual 'flashbacks' - glimpses of elements of the original experience, such as a colour, or a smell, or a voice. They can be very direct and uncontrolled, partly because our 'goal-oriented self' has not been able to file the event properly in any particular filing cabinet, so it just flies back into our consciousness without warning, and without a sense of control.
In summary, we tend to remember events relevant to our goals, objectives and priorities, and organize our memories on this basis. So if you want to create a memorable experience for someone, find out what their priorities and values are in life, and create an experience which helps them to achieve or push forward these goals. Then they will remember you fondly by the fireside, when they are old!