Georgia executed Troy Davis last week and I've been thinking a lot about the death penalty. I've often been a proponent of the death penalty in some cases. Some crimes are so heinous, so horrific, that the death penalty feels like justice. But as a cognitive psychologist, I worry that we create injustice by condoning a system that allows execution. Sometimes we may execute the innocent.
Here's my basic problem: People are horrible eyewitnesses. We misperceive things. Our memories are limited. We create false memories in response to misleading suggestions. We reconstruct our memories. People frequently choose somebody in a police line-up even when the culprit isn't there. We are victims of social pressure from friends, family, and authority figures. We are falsely confident after memory errors. The limitations of eyewitness perception, memory, and cognition are almost innumerable.
How bad is the problem of eyewitness memory? The Innocence Project (click to visit their website) reports that "Eyewitness misidentification is the single greatest cause of wrongful convictions, playing a role in 75% of convictions overturned through DNA testing." As a cognitive psychologist, I have no doubt about the fallibility of human perception and memory. No legal system should take someone's life based solely or primarily on eyewitness identification.