One of the first scientists to realize that the traditional view does not accurately describe the way human memory operates had his epiphany after a case of false testimony—his own. Hugo Münsterberg was a German psychologist.9 He hadn’t started out intending to study the human mind, but when he was a student at the University of Leipzig he attended a series of lectures by Wilhelm Wundt. That was in 1883, just a few years after Wundt had started his famous psychology lab. Wundt’s lectures not only moved Münsterberg, they changed his life. Two years later Münsterberg completed a PhD under Wundt in physiological psychology, and in 1891 he was appointed assistant professor at the University of Freiburg. That same year, while attending the First International Congress in Paris, Münsterberg met William James, who had been impressed by his work. James was then officially the director of the new Harvard Psychological Laboratory, but he wanted to resign from the post to focus on his interests in philosophy. He lured Münsterberg across the Atlantic as his replacement, despite the fact that although Münsterberg could read English he could not speak it.
The incident that inspired Münsterberg’s particular interest in memory occurred a decade and a half later, in 1907.10 While he was vacationing with his family at the seashore, his home in the city was burglarized. Informed of this by the police, Münsterberg rushed back and took stock of the condition of his house. Later, he was called to testify under oath about what he had found. He gave the court a detailed account of his survey, which included the trail of candle wax he had seen on the second floor, a large mantel clock the burglar had wrapped in paper for transport but then left on the dining room table, and evidence that the burglar had entered through a cellar window. Münsterberg testified with great certainty, for as a scientist and a psychologist, he was trained in careful observation, and he was known to have a good memory, at least for dry intellectual facts. “During the last eighteen years,” Münsterberg once wrote, “I have delivered about three thousand university lectures. For those three thousand coherent addresses I had not once a single written or printed line or any notes whatever on the platform…. My memory serves me therefore rather generously.” But this was no university lecture. In this case, each of the above statements proved to be false. His confident testimony, like Dean’s, was riddled with errors.
Those errors alarmed Münsterberg. If his memory could mislead him, others must be having the same problem. Maybe his errors were not unusual but the norm. He began to delve into reams of eyewitness reports, as well as some early pioneering studies of memory, in order to investigate more generally how human memory functions. In one case Münsterberg studied, after a talk on criminology in Berlin, a student stood up and shouted a challenge to the distinguished speaker, one Professor Franz von Liszt, a cousin of the composer Franz Liszt. Another student jumped to his feet to defend von Liszt. An argument ensued. The first student pulled a gun. The other student rushed him. Then von Liszt joined the fray. Amid the chaos, the gun went off. The entire room erupted into bedlam. Finally von Liszt shouted for order, saying it was all a ruse. The two enraged students weren’t really students at all but actors following a script. The altercation had been part of a grand experiment. The purpose of the exercise? To test everyone’s powers of observation and memory. Nothing like a fake shootout in psych class to liven things up.
After the event, von Liszt divided the audience into groups. One group was asked to immediately write an account of what they had seen, another was cross-examined in person, and others were asked to write reports a little later. In order to quantify the accuracy of the reports, von Liszt divided the performance into fourteen bite-sized components, some referring to people’s actions, others to what they said. He counted as errors omissions, alterations, and additions. The students’ error rates varied from 26 to 80 percent. Actions that never occurred were attributed to the actors. Other important actions were missed. Words were put into the arguing students’ mouths, and even into the mouths of students who had said nothing.
As you might imagine, the incident received a fair amount of publicity. Soon staged conflicts became the vogue among psychologists all over Germany. They often involved, as the original had, a revolver. In one copycat experiment, a clown rushed into a crowded scientific meeting, followed by a man wielding a gun. The man and the clown argued, then fought and, after the gun went off, ran out of the room—all in less than twenty seconds. Clowns are not unheard of in scientific meetings, but they rarely wear clown costumes, so it is probably safe to assume that the audience knew the incident was staged, and why. But although the observers were aware that a quiz would follow, their reports were grossly inaccurate. Among the inventions that appeared in the reports were a wide variety of different costumes attributed to the clown and many details describing the fine hat on the head of the man with the gun. Hats were common in those days, but the gunman had not worn one.
From the nature of these memory errors, and those documented in many other incidents he studied, Münsterberg fashioned a theory of memory. He believed that none of us can retain in memory the vast quantity of details we are confronted with at any moment in our lives and that our memory mistakes have a common origin: they are all artifacts of the techniques our minds employ to fill in the inevitable gaps. Those techniques include relying on our expectations and, more generally, on our belief systems and our prior knowledge. As a result, when our expectations, beliefs, and prior knowledge are at odds with the actual events, our brains can be fooled.
For example, in his own case, Münsterberg had overheard police conversations about the burglar entering through the cellar window and, without realizing it, incorporated that information into his memory of the crime scene. But there was no such evidence, for, as the police later discovered, their initial speculation had been wrong. The burglar had actually entered by removing the lock on the front door. The clock Münsterberg remembered packed in paper for transport had actually been packed in a tablecloth, but, as Münsterberg wrote, his “imagination gradually substituted the usual method of packing with wrapping paper.” As for the candle wax he so clearly remembered having seen on the second floor, it was actually in the attic. When he spotted it, he wasn’t aware of its importance, and by the time the issue came up, he was focused on the strewn papers and other disorder on the second floor, apparently causing him to recall having seen the candle wax there.
Münsterberg published his ideas about memory in a book that became a best seller, On the Witness Stand: Essays on Psychology and Crime.11 In it, he elaborated on a number of key concepts that many researchers now believe correspond to the way memory really does work: first, people have a good memory for the general gist of events but a bad one for the details; second, when pressed for the unremembered details, even well-intentioned people making a sincere effort to be accurate will inadvertently fill in the gaps by making things up; and third, people will believe the memories they make up.