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Science Of Small Talk

The science of social behavior, one interaction at a time

by Sam Sommers

Sam Sommers, Ph.D., is a social psychologist at Tufts University. See full bio

March 11, 2009, Law and Crime

Comments on "Not Who I Thought You Were"

Not Who I Thought You Were

By Sam Sommers on March 11, 2009 in Science Of Small Talk

It seems like such an easy thing to do, to recall a person you saw weeks, days, or even hours earlier. But it's not... Student: "That reminds me of a presentation I sat through during freshman orientation." Me: "Right, I was one of those presenters." Student: "No, there was a Black professor and a White professor, but the White guy was someone else." Me: "Actually, that was me. I conduct diversity workshops, including that one at freshman orientation." Student: "No, the White professor wasn't you; it was another guy." Read More

Good stuff Sam. I was

Submitted by Jeff on March 10, 2009 - 6:29pm.

Good stuff Sam. I was fortunate to a prosecutor whose office took these issues seriously and trained us accordingly ... false confessions and problematic ID procedures are arenas that every prosecutor and police department should be trained in, as it is really very easy to raise the odds of getting it right via video recording of all interrogations and avoiding needlessly coercive tactics, and avoiding the multiple choice test with no wrong answer approach to witness identification (as well as avoiding overly suggestive ID procedures by having an officer with no knowledge of the investigation conduct the photo array). The Duke lacrosse case was the most egregious recent example -- even before the inconsistencies in the eyewitness testimony and the problematic handling of evidence came to light, I was absolutely stunned that an experienced prosecutor would show the victim a page full of lacrosse players and let her select which ones were the perpetrators -- the paradigmatic example of a multiple choice test with no wrong answers. Had Nifong followed appropriate procedure of showing her photos one by one, without a known end point, and with many similar-looking false positives, the case may never have proceeded as far as it did ...

line-up procedure

Submitted by Anonymous on March 11, 2009 - 1:29pm.

do they ever add people to the line-up who were blatantly not involved in the crime (like random employees of the police station)? Adding more people to the line-up, and more people who DEFINITELY had nothing to do with the crime would seem like a good solution to this problem.

reply

Submitted by Sam Sommers on March 12, 2009 - 4:35am.

Sure, that happens. One of the worst things police can do, of course, is to create a line-up in which everyone is a suspect. Because the processes of relative judgment are going to lead most eyewitnesses to pick *some*one, especially if the instructions don't emphasize that the culprit may or may not be in the line-up. And so having known fillers in the line-up decreases the chances that an innocent person becomes a suspect-- if the witness picks a known filler, then no one innocent gets arrested and the police learn that the witness isn't that reliable.

But data suggest that the majority of line-ups are of the photo variety, not the in-person, "Usual Suspects" type of line-up we usually think of. In such instances, the police have a lot more flexibility with how they construct things. Without getting into too much detail, one of the important considerations is the *functional size* of the line-up, as opposed to the sheer number of people in it. "Functional size" refers to how many plausible choices are in the line-up given the description of the culprit provided by the crime scene witness. If the witness says the guy had red hair, then adding brunettes to the line-up doesn't increase its functional size. Dr. Gary Wells' website (linked in the blog post) provides some excellent examples.