She Was Certain, but She Was Wrong
In 1984 Jennifer Thompson was a 22-year-old college student in North Carolina. One night a man broke into her apartment, put a knife to her throat, and raped her. According to her own account, Ms. Thompson studied her rapist throughout the incident with great determination to memorize his face. She said:
I studied every single detail on the rapist’s face.I looked at his hairline; I looked for scars,for tattoos, for anything that would help me identify him.When and if I survived.
Ms. Thompson went to the police that same day to create a sketch of her attacker, relying on what she believed was her detailed memory. Several days later, the police constructed a photographic lineup. Thompson identified Ronald Cotton as the rapist, and she later testified against him at trial. She was positive it was him, with no doubt in her mind.
I was sure.I knew it.I had picked the right guy,and he was going to go to jail. If there was the possibility of a death sentence,I wanted him to die. Iwanted to flip the switch.
As positive as she was, it turned out that Jennifer Thompson was wrong. But it was no t until after Mr. Cotton had served 11 years in prison for a crime he did not commit that conclusive DNA evidence indicated that Bobby Poole was the actual rapist, and Cotton was released from jail. Jennifer Thompson’s memory had failed her, resulting in a substantial injustice. It took definitive DNA testing to shake her confidence, but she now knows that despite her confidence in her identification, it was wrong. Consumed by guilt, Thompson sought out Cotton when he was released from prison, and they have since become friends (Innocence Project, n.d.; Thompson, 2000). 1
Picking Cotton: A Memoir of Injustice and Redemption
Although Jennifer Thompson was positive that it was Ronald Cotton who had raped her, her memory was inaccurate. Conclusive DNA testing later proved that he was not the attacker. Watch this book trailer about the story. Jennifer Thompson is not the only person to have been fooled by her memory of events. Over the past 10 years, almost 400 people have been released from prison when DNA evidence confirmed that they could not have committed the crime for which they had been convicted. And in more than three-quarters of these cases, the cause of the innocent people being falsely convicted was erroneous eyewitness testimony (Wells, Memon, & Penrod, 2006). 2 Eyewitness Testimony Watch this video for Lesley Stahl’s 60 Minutes segment on this case.
The two subjects of this chapter are memory, defined as theabilityto storeand retrieve information over time, and cognition, defined as theprocesses of acquiringand using knowledge. It is useful to consider memory and cognition in the same chapter because they work together to help us interpret and understand our environments.
Memory and cognition represent the two major interests of cognitive psychologists. The cognitive approach became the most important school of psychology during the 1960s, and the field of psychology has remained in large part cognitive since that time. The cognitive school was influenced in large part by the development of the electronic computer, and although the differences between computers and the human mind are vast, cognitive psychologists have used the computer as a model for understanding the workings of the mind.
Differences between Brains and Computers
- In computers, information can be accessed only if one knows the exact location of the memory. In the brain, information can be accessed through spreading activationfrom closely related concepts.
- The brain operates primarily in parallel, meaning that it is multitasking on many different actions at the same time. Although this is changing as new computers are developed, most computers are primarily serial—they finish one task before they start another.
- In computers, short-term (random-access) memory is a subset of long-term (read-only) memory. In the brain, the processes of short-term memory and long-term memory are distinct.
- In the brain, there is no difference between hardware (the mechanical aspects of the computer) and software (the programs that run on the hardware).
- In the brain, synapses, which operate using an electrochemical process, are much slower but also vastly more complex and useful than the transistors used by computers.
- Computers differentiate memory (e.g., the hard drive) from processing (the central processing unit), but in brains there is no such distinction. In the brain (but not in computers) existing memory is used to interpret and store incoming information, and retrieving information from memory changes the memory itself.
- The brain is self-organizing and self-repairing, but computers are not. If a person suffers a stroke, neural plasticity will help him or her recover. If we drop our laptop and it breaks, it cannot fix itself.
- The brain is significantly bigger than any current computer. The brain is estimated to have 25,000,000,000,000,000 (25 million billion) interactions among axons, dendrites, neurons, and neurotransmitters, and that doesn’t include the approximately 1 trillion glial cells that may also be important for information processing and memory.
Although cognitive psychology began in earnest at about the same time that the electronic computer was first being developed, and although cognitive psychologists have frequently used the computer as a model for understanding how the brain operates, research in cognitive neuroscience has revealed many important differences between brains and computers. The neuroscientist Chris Chatham (2007) 3 provided the list of differences between brains and computers shown here. You might want to check out the website and the responses to it at http://scienceblogs.com/developingintelligence/2007/03/why_the_brain_is_not_ like_a_co.php.
We will begin the chapter with the study of memory. Our memories allow us to do relatively simple things, such as remembering where we parked our car or the name of the current president of the United States, but also allow us to form complex memories, such as how to ride a bicycle or to write a computer program. Moreover, our memories define us as individuals— they are our experiences, our relationships, our successes, and our failures. Without our memories, we would not have a life.
At least for some things, our memory is very good (Bahrick, 2000). 4 Once we learn a face, we can recognize that face many years later. We know the lyrics of many songs by heart, and we can give definitions for tens of thousands of words. Mitchell (2006) 5contacted participants 17 years after they had been briefly exposed to some line drawings in a lab and found that they still could identify the images significantly better than participants who had never seen them.
For some people, memory is truly amazing. Consider, for instance, the case of Kim Peek, who was the inspiration for the Academy Award–winning film Rain Man (Figure 8.1 "Kim Peek" [Missing] and Video Clip: Kim Peek). Although Peek’s IQ was only 87, significantly below the average of about 100, it is estimated that he memorized more than 10,000 books in his lifetime (Wisconsin Medical Society, n.d.; “Kim Peek,” 2004). 6 The Russian psychologist A. R. Luria (2004) 7 has described the abilities of a man known as “S,” who seems to have unlimited memory. S remembers strings of hundreds of random letters for years at a time, and seems in fact to never forget anything.