Eyewitness Testimony and Memory Issues When Investigating

¶ … Eyewitness Testimony and Memory Issues

When investigating and prosecuting crimes and other incidents, their can be a heavy level of reliance on eyewitness testimony to substantiate the facts that are suggested by other evidence and to fill in missing gaps in the story of the crime, accident, or other incident. This can be a problem, however, as two different eyewitness accounts of the same incident are likely to differ significantly in many ways, and even the same eyewitness can remember details differently at different intervals of time following the incident. This is due to the human function of memory: the differences between short- and long-term memory, the processes involved in creating and reinforcing memory, and various techniques that can be used to help bring out memories but are not always reliable. This paper will examine and explore many of the issues related to memory and eyewitness recall.

Short-term memory occurs when sensory information is stored temporarily for use in certain comparisons and decision-making processes, like holding information from the beginning of a sentence until you reach the end of a sentence so that the entire sentence makes sense (Georgia 2011). Short-term memory decays quickly, and within a few seconds things stored in short-term memory are either forgotten or moved into long-term memory (Georgia 2011). When new neural pathways are formed in order to store information in long-term memory, there is very little decay that actually occurs, meaning that everything that actually makes it to long-term memory is theoretically accessible for the rest of the brain's life (Georgia 2011). Things do not actually work quite as simply as theory suggests, however.

The first step of memory creation is called encoding, and it is the direct biological reaction of the senses to new information that is received -- that is, encoding is made up of the specific sensory information associated with a particular memory (Discovery 2011). The sights, smell, sounds, and touch (when applicable) of a particular person upon initially meeting them might all be information that becomes encoded as part of a particular memory (Discovery 2011). When memories are later recalled, the same sensory areas in the brain often light up, which is indicative of the importance of this initial encoding in the establishment and preservation of long-term memories (Holladay 2007). This sensory information is at first only stored as very temporary information, however, and it must be moved into short-term memory before the encoded pathways are made in any way consciously useful (Holladay 2007).

The storage of memory in short- and then long-term memory occurs as various chemical and physical changes take place, in response to certain electrical cues and chains of activity that can ultimately result in the creation of new neural pathways -- physical and electrical interconnections that did not exist before a memory was stored (Radvansky 2010). Retrieving a memory is even less understood than the process of forming a memory, but basically another series of electric and chemical impulses create the re-triggering of pathways encoded with a specific memory and that memory surfaces (Holladay 2007). There can be problems with the retrieval circuit, such as the brain simply not activating the right memory, but more often problems with "retrieval" are really problems with initial memory storage (Discovery 2011).

Eyewitnesses often have different accounts of the same event not because they are "bad" at remembering, but because they initially stored or encoded different information, different parts of which ultimately ended up in their long-term accessible memory. The "forgetting curve" helps to illustrate this fact. Created by graphing the amount of memory lost after certain intervals of time, the forgetting curve provides a clear visual representation of the rate at which memories deteriorate: very rapidly in the period immediately following an event, and then much more gradually (or even imperceptibly) after a certain period of time (Cherry 2011). As has already been stated, short-term memory quickly deteriorates, but long-term memory is incredibly stable. The actual experiments from which the curve was first developed, however, suggest that there is a mid-level memory storage system; traditional short-term memory is stored for only a few seconds, but the period of memory deterioration lasts several days in most instances (Cherry 2011).

Another major issue that is faced when collecting eyewitness accounts of an incident is the ability for the human mind to create false memories. Existing memories can have an impact on the formation of new memories, leading to a memory of associations and details that are not necessarily present (Cherry 2011). Mis-remembering the original source of a piece of information -- believing it was something personally seen instead of simply heard from another witness, for example -- is another common false memory formation (Cherry 2011). Almost anything imagined or observed incorrectly can become store din long-term memory as a false memory.