Charles Stangor, Jennifer Walinga, and Lee Sanders
Memory and cognition are the two major interests of cognitive psychologists. The cognitive school was influenced in large part by the development of the electronic computer. Psychologists conceptualize memory in terms of types, stages, and processes.
Explicit memory is assessed using measures in which the individual being tested must consciously attempt to remember the information. Explicit memory includes semantic and episodic memory. Explicit memory tests include recall memory tests, recognition memory tests, and measures of relearning (also known as savings).
Implicit memory refers to the influence of experience on behaviour, even if the individual is not aware of those influences. Implicit memory is made up of procedural memory, classical conditioning effects, and priming. Priming refers both to the activation of knowledge and to the influence of that activation on behaviour. An important characteristic of implicit memories is that they are frequently formed and used automatically, without much effort or awareness on our part.
Sensory memory, including iconic and echoic memory, is a memory buffer that lasts only very briefly and then, unless it is attended to and passed on for more processing, is forgotten.
Information that we turn our attention to may move into short-term memory (STM). STM is limited in both the length and the amount of information it can hold. Working memory is a set of memory procedures or operations that operates on the information in STM. Working memory’s central executive directs the strategies used to keep information in STM, such as maintenance rehearsal, visualization, and chunking.
Long-term memory (LTM) is memory storage that can hold information for days, months, and years. The information that we want to remember in LTM must be encoded and stored, and then retrieved. Some strategies for improving LTM include elaborative encoding, relating information to the self, making use of the forgetting curve and the spacing effect, overlearning, and being aware of context- and state-dependent retrieval effects.
Memories that are stored in LTM are not isolated but rather are linked together into categories and schemas. Schemas are important in part because they help us encode and retrieve information by providing an organizational structure for it.
The ability to maintain information in LTM involves a gradual strengthening of the connections among the neurons in the brain, known as long-term potentiation (LTP). The hippocampus is important in explicit memory, the cerebellum is important in implicit memory, and the amygdala is important in emotional memory. A number of neurotransmitters are important in consolidation and memory. Evidence for the role of different brain structures in different types of memories comes in part from case studies of patients who suffer from amnesia.
Cognitive biases are errors in memory or judgment that are caused by the inappropriate use of cognitive processes. These biases are caused by the overuse of schemas, the reliance on salient and cognitive accessible information, and the use of rule-of-thumb strategies known as heuristics. These biases include errors in source monitoring, the confirmation bias, functional fixedness, the misinformation effect, overconfidence, and counterfactual thinking. Understanding the cognitive errors that we frequently make can help us make better decisions and engage in more appropriate behaviours.
Eyewitness testimony is very powerful and convincing to jurors, even though it is not particularly reliable. Identification errors occur, and these errors can lead to people being falsely accused and even convicted. Likewise, eyewitness memory can be corrupted by leading questions, misinterpretations of events, conversations with co-witnesses, and their own expectations for what should have happened. People can even come to remember whole events that never occurred.
The problems with memory in the legal system are real. Misinformation can be introduced into the memory of a witness between the time of seeing an event and reporting it later.
The misinformation effect occurs when misinformation that subjects are exposed to after the event contaminates subjects’ memories of what they witnessed. Hundreds of studies have demonstrated that memory can be contaminated by erroneous information that people are exposed to after they witness an event.
False memory studies suggest that once these false memories are implanted it is difficult to tell them apart from true memories.
In addition to correctly remembering the many details of a crime, eyewitnesses often need to remember the faces and other identifying features of the perpetrators of those crimes. There is a substantial body of research demonstrating that eyewitnesses can make serious, but often understandable and even predictable, errors while engaging with mug shots, photo spreads, and line ups. Memory is also susceptible to a wide variety of biases and errors. People can forget events that happened to them and people they once knew. They can mix up details across time and place. They can even remember whole complex events that never happened at all.
Recommendations have been made to improve the use of and reliance on the use of eyewitness testimony in the legal system, and many of these are in the process of being implemented. Some are aimed at specific legal procedures, including when and how witnesses should be interviewed, and how lineups should be constructed and conducted. Other recommendations call for appropriate education (often in the form of expert witness testimony) to be provided to jury members and others tasked with assessing eyewitness memory.
Eyewitness testimony can be of great value to the legal system, but decades of research now argues that this testimony is often given far more weight than its accuracy justifies.
Contributors and Attributions
- Introduction to Psychology by Jorden A. Cummings & Lee Sanders is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.
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