Kluge: The Haphazard Construction of the Human Mind (Houghton Mifflin; 2008)

In another experiment, Loftus asked several different groups of subjects (all of whom had seen a film of another car accident) slightly different questions, such as How fast were the cars going when they hit each other? or How fast were the cars going when they smashed into each other? All that varied from one version to the next was the final verb (hit, smashed, contacted, and so forth). Yet this slight difference in wording was enough to affect people's memory: subjects who heard verbs like smashed estimated the crash as occurring at 40.8

miles per hour, a significantly greater speed than that reported by those who heard verbs with milder connotations, like hit (34.0) and contacted (31.8). The word smashed cues different memories than hit, subtly influencing people's estimates.

Both studies confirm what most lawyers already know: questions can 'lead witnesses.' This research also makes clear just how unreliable memory can be. As far as we can tell, this pattern holds just as strongly outside the lab. One recent real-world study, admittedly small, concerned people who had been wrongly imprisoned (and were subsequently cleared on the basis of DNA tests). Over 90 percent of their convictions had hinged on faulty eyewitness testimony.

When we consider the evolutionary origins of memory, we can start to understand this problem. Eyewitness testimony is unreliable because our memories are stored in bits and pieces; without a proper system for locating or keeping them together, context affects how well we retrieve them. Expecting human memory to have the fidelity of a video recorder (as juries often do) is patently unrealistic. Memories related to accidents and crimes are, like all memories, vulnerable to distortion.

A memorable line from George Orwell's novel 1984 states that 'Oceania had always been at war with Eurasia' — the irony being, of course, that until recently (in the time frame of the book) Oceania had not in fact been at war with Eurasia. ('As Winston well knew, it was only four years since Oceania had been at war with Eastasia and in alliance with Eurasia.') The dictators of 1984 manipulate the masses by revising history. This idea is, of course, essential to the book, but when I read it as a smug teenager, I found the whole thing implausible: wouldn't people remember that the battle lines only recently had been redrawn? Who was fooling whom?

Now I realize that Orwell's conceit wasn't so far-fetched. All memories — even those concerning our own history — are constantly being revised. Every time we access a memory, it becomes 'labile,' subject to change, and this seems to be true even for memories that seem especially important and firmly established, such as those of political events or our own experiences.

A good, scientifically well documented illustration of how vulnerable autobiographical memory can be took place in 1992, courtesy of the ever-mercurial Ross Perot, an iconoclastic billionaire from Texas who ran for president as an independent candidate. Perot initially attracted a strong following, but suddenly, under fire, he withdrew from the race. At that point an enterprising psychologist named Linda Levine asked Perot followers how they felt about his withdrawal from the campaign. When Perot subsequently reentered the race, Levine had an unanticipated chance to collect follow-up data. Soon after election day, Levine asked people whom they voted for in the end, and how they felt about Perot earlier in the campaign, at the point when he had dropped out. Levine found that people's memory of their own feelings shifted. Those who returned to Perot when Perot reentered the race tended to whitewash their negative memories of his withdrawal, forgetting how betrayed they had felt, while people who moved on from Perot and ultimately voted for another candidate whitewashed their positive memories of him, as if they had never intended to vote for him in the first place. Orwell would have been proud.*

Distortion and interference are just the tip of the iceberg. Any number of things would be a whole lot easier if evolution had simply vested us with postal-code memory. Take, for example, the seemingly trivial task of remembering where you last put your house keys. Nine

^Several other studies have pointed to the same conclusion — we all tend to be historical revisionists, with a surprisingly dodgy memory of our own prior attitudes. My own personal favorite is an article called 'From Chump to Champ' — it describes the one instance in which we all are happy to endure ostensibly negative memories about our own past: when it helps paint us, Rocky-style, as triumphing over adversity.

times out of ten you may get it right, but if you should leave your keys in an atypical spot, all bets are off. An engineer would simply assign a particular memory location (known as a 'buffer') to the geographical coordinates of your keys, update the value whenever you moved them, and voil?: you would never need to search the pockets of the pants you wore yesterday or find yourself locked out of your own home.

Alas, precisely because we can't access memories by exact location, we can't straightforwardly update specific memories, and we can't readily 'erase' information about where we put our keys in the past. When we place them somewhere other than their usual spot, recency (their most recent location) and frequency (where they're usually placed) come into conflict, and we may well forget where the keys are. The same problem crops up when we try to remember where we last put our car, our wallet, our phone; it's simply part of human life. Lacking proper buffers, our memory banks are a bit like a shoebox full of disorganized photographs: recent photos tend on average to be closer to the top, but this is not guaranteed. This shoebox-like system is fine when we want to remember some general concept (say, reliable locations for obtaining food) — in which case, remembering any experience, be it from yesterday or a year ago, might do. But it's a lousy system for remembering particular, precise bits of information.

The same sort of conflict between recency and frequency explains the near-universal human experience of leaving work with the intention of buying groceries, only to wind up at home, having completely forgotten to stop at the grocery store. The behavior that is common practice (driving home) trumps the recent goal (our spouse's request that we pick up some milk).

Preventing this sort of cognitive autopilot should have been easy. As any properly trained computer scientist will tell you, driving home and getting groceries are goals, and goals belong on a stack. A computer does one thing, then a user presses a key and the first goal (analogous to driving home) is temporarily interrupted by a new goal (getting groceries); the new goal is placed on top of the stack (it becomes top priority), until, when it is completed, it is removed from the stack, returning the old goal to the top. Any number of goals can then be pursued in precisely the right priority sequence. No such luck for us human beings.

Or consider another common quirk of human memory: the fact that our memory for what happened is rarely matched by memory for when it occurred. Whereas computers and videotapes can pinpoint events to the second (when a particular movie was recorded or particular file was modified), we're often lucky if we can guess the year in which something happened, even if, say, it was in the headlines for months. Most people my age, for example, were inundated a few years ago with a rather sordid story involving two Olympic figure skaters; the ex-husband of one skater hired a goon to whack the other skater on the knee, in order to ruin the latter skater's chance at a medal. It's just the sort of thing the media love, and for nearly six months the story was unavoidable. But if today I asked the average person when it happened, I suspect he or she would have difficulty recalling the year, let alone the specific month.*