8 NOVEMBER 2003, Page 69

Airbrushing out and filling in

Nicholas Fearn

How THE MIND FORGETS AND REMEMBERS: THE SEVEN SINS OF MEMORY by Daniel L. Schacter Souvenir, £18.99, pp. 206, ISBN 0285636839 If one ever wonders just how important memory is to our selfhood, consider patients in the later stages of Alzheimer's disease. The condition as good as demonstrates that there is no afterlife, because if you can be dead when you are alive, then you can certainly be dead when you are dead. Without memory our minds are nothing, which should have made the cynical among us realise long ago that something so important could not possibly be fully under our control. According to the research psychologist Daniel Schacter, memory is far from the passive aide we imagine — the dutiful if fallible servant who hopefully brings us what we need, when we need it. Memory is rather one who alternates nights of mischief while his lordship is away with moments of wellintentioned artifice, like the butler who concocts fan letters for his faded movie star mistress in Sunset Boulevard.

Schacter shows how our memories are constantly inventing and obscuring the truth behind our backs, plugging gaps and remoulding the past to suit the present. For example, in the light of a known outcome we more easily recall incidents that confirm it. When a murderer turns out to be the very same father of the victim who gave a tearful plea for information on the television, we immediately remember how we could 'see the guilt in his eyes' and really 'knew all along', though for some reason we omitted to mention it at the time. On the other hand, if accounts of recollection are not to be trusted, the author needs reminding that neither are those of forgetfulness. It should seem at least suspicious that one's friend's alcoholic amnesia never seems to blot out his big casino wins or trysts with top models, and takes care only to excise the moment when he kissed the transvestite.

The subtitle is correct to brand mnemonic vices 'sins', because they produce the same shame as ordinary wrongdoing when you forget an anniversary or the name of an acquaintance. Such failures compromise our everyday moral competence — which for most of us, being mercifully free of true malevolence, is more or less the whole of morality. As is too often the case with ordinary moral failure, many of us are guilty while thinking ourselves innocent. Schacter cites an analysis of 40 criminal cases from the US in which DNA evidence established the innocence of wrongly convicted individuals. Thirty-six of them involved mistaken eyewitness identification. Yet each year in the US over 75,000 trials are decided on the basis of eyewitness testimony.

It is a pity that the book is not limited to such studies and surveys, but expands from the psychology of memory into neuroscience. Tacked onto each section is an unhelpful description of the brain states that accompany the behaviour under discussion. In one example from the literature, an epilepsy patient has the left temporal pole — whatever that may be — removed from his brain and is rendered unable to remember people's names. Moreover, neuro-imaging scans reveal that our temporal poles light up (or do whatever it is that they do) when we remember names. So there we have it: we forget because of something that happens in the brain. And there we were thinking that pixies came and took away our memories in the night. Presumably, neuro-imaging technology has many wonderful uses, but they are not on show this time. They rarely are. It seems to be a legitimate arm of scientific method these days to produce colour plates from one scan or another, grin inanely and pronounce another mystery solved. At least we are spared the pictures here. The most comforting discovery for the absent-minded among us in this work will he the fact that strong recollections are the product of the same neural pathways being used again and again. As we always knew, a good memory is the sign of a repetitive mind.