I could have mentioned any number of studies to support the idea of the fallibility of memory. The study I mentioned (call it the 'hot-air balloon study') is a particularly striking demonstration of how our memories can be tricked. The experiment was conducted by Kimberley Wade, now at Warwick University, with colleagues from New Zealand and Canada. As I describe in the piece, adult participants were asked to look at some photographs from their childhood without being told that one of the pictures had been doctored (it depicted a hot-air balloon ride which, it could be verified, had never happened). When interviewed again after about two weeks, around half of the participants 'remembered' the event, and were surprised to hear that it had been invented.
A little while ago I quoted Hilary Mantel on the vividness of early memories, and her conviction that this vividness vouched for their authenticity. Earlier in the same passage, Mantel has this to say:
Sometimes psychologists fake photographs in which a picture of their subject, in his or her childhood, appears in an unfamiliar setting, in places or with people who, in real life they have never seen. The subjects are amazed at first but then—in proportion to their anxiety to please—they oblige by producing a 'memory' to cover the experience that they have never actually had. I don't know what this shows, except that some psychologists have persuasive personalities, that some subjects are imaginative, and that we are all told to trust the evidence of our senses, and we do it: we trust the objective fact of the photograph, not our subjective bewilderment. It's a trick, it isn't science; it's about our present, not about our past.
Hilary Mantel, Giving Up the Ghost (2003)
I don't know which research Mantel had in mind, but I'm sure that in the hot-air balloon study participants weren't swayed by persuasive personalities. Actually, Mantel unwittingly hits the nail on the head: memory is about the present, not the past. Memories are constructed to meet the needs of now (which, from an evolutionary point of view, is arguably all the brain is actually interested in).
But Mantel is right that there is something about the hot-air balloon study that lacks ecological validity. To address these concerns, Wade and colleagues followed up their study with another experiment, which I'll call the Slime study. In this experiment, adult participants heard some narratives, provided by their own parents, of events that had happened in the participant's school days. Two of these narratives were genuine, and one other was fake. Specifically, the subjects were 'told' that they had tricked their primary school teacher by putting some green slime in the teacher's desk. (Parents confirmed that this had never actually happened.) The narrative went on to say that the child been caught and subsequently punished. As you would expect, given what we know about the suggestibility of memory, nearly half of the subjects reported some 'memory' for this pseudoevent.
So far, all this does is remind us that memory is easily tricked. But the Slime experiment went further. A separate group of participants followed the same procedure, but these individuals also looked at a class photo taken at the time they were supposed to be recalling. In this group, the rate of false memories jumped from 45% to 78%. In contrast to the hot-air balloon study, the photos themselves were genuine, but they were integrated with other (false) bits of information to create a vivid, and unfounded, 'memory'.
In my own article, I am suggesting that children probably do the same kind of integration of visual images with other kinds of information in creating memories of events that could never actually have happened. The kids know what Grandad Philip looked like, and they can listen to my stories about him. The imaginative storyteller that is memory does the rest.