By Emma Young
Where were you at 8 a.m. two Tuesdays ago? If it is a little difficult to remember, what if I presented you with a map with four location flags to choose from, each about 3-4 km apart, with one marking your actual location at that time and date? Are you sure you would choose the right one?
If you are confident of the good news of a new newspaper in psychology is you are more likely to be right than if you are not sure. The bad news is that a group of students in Melbourne, Australia tested this way, chose the wrong location 36% of the time. The study shows that this type of memory is quite fallible – and yet, of course, it is the type needed for a criminal alibi. Failure to remember where you were has undoubtedly contributed to serious legal errors, write Elizabeth Laliberte of the University of Melbourne and her colleagues.
The 51 students all downloaded an app that had been developed by two of the researchers on their cell phones. Over a period of four weeks, this app continuously tracked your movement and orientation and took GPS location and audio snapshots every ten minutes. Software removed all speech from these audio files, but retained background noises such as birds chirping or construction work. (The app was designed to keep the participants’ raw data secret from the researchers themselves, and participants were allowed to pause data collection for some time.)
After a week’s delay, the participants were retested via the app. For each of 72 attempts, they had to use four markers on a Google map to choose where they were at a specific time and date. (You could zoom in and out and pan at will). One of these markings represented the correct location, and the other three represented locations they had been to on other occasions.
The team’s analysis showed that the students as a group were correct only about two-thirds of the time. Accuracy increased with confidence, a finding that supports the idea that (under certain circumstances) greater confidence is associated with better memory. But the less than perfect performance of these university students, who presumably have fairly regular timetables, doesn’t bode well for the rest of us – especially for people without regular office hours.
The team investigates the case of the American Ronald Cotton, who was sentenced to life imprisonment plus 50 years imprisonment for rape and burglary in 1985. Ten years after the conviction, DNA evidence exonerated him. Cotton’s initial defense was not helped when his alibi was found to be false. “Instead of reporting where he was at the time of the crime, Cotton mistakenly remembered where he was the week before. The mistake probably contributed significantly to his false conviction, ”write the researchers.
The team’s analysis suggests that this mistake occurs relatively frequently: Choosing a location “right day, wrong week” accounted for 19% of the participants’ mistakes. Participants also often chose a location that was right at the set hour but wrongly the day – this mistake accounted for 8% of mistakes. (They also sometimes chose the wrong place, where they had made similar movement patterns, or where the background noise resembled the correct position – although these mistakes were less common). “Both numbers are way above the odds and suggest that the mistake Ronald Cotton made could be quite common,” the team writes.
It is clear that the results could have practical, legal applications. Knowing how fallible this type of alibi reminder is – and understanding the most common mistakes people make – could help lawyers ask defendants and witnesses the right questions, and try to get closer to the truth of where someone really is at a given point in time was located.
But there are more general implications for understanding memory and the way memory research is done. Experiments often take place in the laboratory and raise questions about practical applicability. Passive, inconspicuous, privacy conscious surveillance technologies like this new app could be used to collect and analyze all kinds of real world data. As the researchers write, “We are now able to grasp the basic truth of people’s lives and test their ability to store these events.” And this, they hope, could change the way a lot of memory research is done.
– The Airtight Alibi Fallacy: Understanding Human Memory for the “Where” Using Experience Sampling
Emma Young (@EmmaELJunge) works at BPS Biomedarticles