Memory is such an intriguing, yet troubling, part of cognitive psychology and everyday
life. For whatever reason, we use our ability to remember things as a shorthand measure for
judging our general cognitive abilities. And yet, chances are, a huge amount of what we "remember"
never happened... not that we'd ever realise -where we tack in memory, we more than make up
for in the skill of self-deception! So, what's the story of our cheeky,
less-than-reliable variety? After all, I thought long term memory is supposed to be unlimited and
last a lifetime. Well, it turns out things might be a tad more complicated than that.
The fallibility of human memory is nothing new, back in 1895, Hermann Ebbinghaus used himself as
the participant in a study on how long he could remember a list of 13 nonsense-syllables - WEX,
P1B, DEP and the like. Ebbinghaus - a man with one too many hobbies - would assess
how long it took him to relearn the list after various lengths of time,
ranging from a couple of minutes to thirty-one days. And what he found was that his ability
to recall the list of nonsense syllables nosedived fairly quickly over the period of one or two days,
but even after a whole month he was still able to recall some information from his list.
So what can we learn from Ebbinghaus' efforts to keep himself entertained,
apart from that he needed to get out more? Well, it's that our memories aren't absolute - let's add
some context with a couple of more recent studies. Bahrick et al. (1975) wanted to find out
what graduates could remember of their classmates as time passed after graduating.
The researchers asked participants to free-recall who they graduated alongside, and also provided
participants with photos to match up with names. Whilst the ability to recognise names
and faces of former classmates remained pretty high for 15 years after graduating,
as the retention interval increased, participants I recall abilities lessened.
In 1984, Bahrick conducted a similar experiment, this time considering people's
ability to remember the Spanish they'd learned at school. Bahrick and his fellow researchers
found that recall decreased over the first six years after graduation, before steadying for
the next 35 years and decreasing thereafter. Bahrick attributes this period of consistent
recall ability to a "permastore", something that he suggests demonstrates deep learning of the
original information, whether that's information about former classmates or useful Spanish phrases.
But Neisse (1984) has another idea, suggesting that people have a
schematic representation of a knowledge domain. To put this another way, we don't know something
or other, we know about something or other. Specific knowledge may not be permanently
available to us, but our cognitive systems of representation-such as schema- allow us to
retrieve information that matches our conceptual expectations. Conceptual knowledge-the general
gist-should therefore be better retained than straightforward facts, like names and doses.
Conway et al. (1991, 1992) support this notion by assessing students' abilities to remember
information learned in a cognitive psychology course. The longitudinal study lasted twelve years
and the researchers found that memory declined over the first three years and then stabilised
(similar to the pattern of loss and stabilisation noted by Bahrick and those Spanish students).
However, Conway et al. additionally note that the recall of proper names declined
more rapidly than did memory for concepts. So, if we recall the contextual gist better than
the explicit details, how do we know whether we're remembering the details accurately?
Well, we're probably not, which is why Bartlett (1934) challenged the concept of memory being a
recollection at all. From his experience of people plugging the gaps in their memories with whatever
made most sense to them, Bartlett goes as far as to suggest memories are creative reconstructions
of what happened... sometimes even total constructions of what the individual thinks should
have happened-and so often, without the person realising they are "recalling" a false memory.
In a brilliantly simple experiment at the beginning of this century,
Roediger et al. (2001) showed participants short videos of
typical household scenarios. Each participant took part in the experiment with another person,
who was actually a Confederate of the researchers. So, after the 15 or 60 second video, the two
participants were asked to collaboratively build a list of household items they saw in the video.
In half of the cases, the Confederate provided household objects that
weren't seen in the video clip, but that contextually would make sense in the scene.
After a short delay, the real participant was privately asked to recall the household objects
seen in the video dip. Those participants who had been paired with a confederate who listed
incorrect items in the collaborative condition were significantly more likely to recall items
that were not featured in the original dip. This was even more noticeable for participants who had
seen a 15 second clip instead of a 60 second dip. The startling thing about these false
recollections is how sure participants were that they had seen objects that they never
saw. Ironically, participants were significantly more likely to say they "knew" on item was in the
scene rather than that they remembered seeing it. This "knowledge" seems rooted in our reliance on
context over detail, something that Johnson et al. (1993) put down to the fact that we receive
information from many different sources all the time. And so, whilst we may recall an individual
scrap of information, we might misattribute it to a different source. Johnson refers to
this as our Source Monitoring Framework, and it may explain why participants in Roediger's study
were so easily misled by the confederate planting false memories in their heads.
All this goes to show that our memories of information and events can be very easily
manipulated, and often without our being any the wiser. What does this mean in practice?
Trust in your ability to remember the gist of something much more than the details... and if
you ever think you really, truly, completely know something for sure... don't be so sure!