Perception vs long term memory Essay Paper

Perception vs long term memory
Perception vs long term memory

Perception vs long term memory;why a witness’ account may differ from reality

Order Instructions:

Explain why a witness’s account of events may differ from what really happened.
– Assume that the witness is fit and healthy and will provide and honest account according to their recollection.
– Research should focus on PERCEPTION and LONG TERM MEMORY.

Writing style as Harvard.


            An incident is reported of a woman that accused Donald Thompson of raping her. A rapist attacked her while she was watching Donald Thompson on a live telecast. The woman confused the rapist’s face with the one she had seen on TV and identified Donald Thompson as the perpetrator. Before the authorities realized that she had confused the face of the rapist with that of Thompson on TV, Thompson had been arrested. The police had dismissed the alibi that the rape occurred when he was on TV and together with the audience and other discussants (Braddeley, 2004). It is a story of how accounts of mentally fit and healthy witnesses with honest intentions may starkly differ from what really happened.  It is an intriguing phenomenon whose explanation lies in the mental processes of perception and long term memory.


The eyes just like other sensory organs have limitations that can cause erroneous identification of objects. For example, a story is told of two men that were in the woods talking and thinking about bears. They then spotted a large object that was moving and making some noise. Their conversation had conditioned them to think that it was a bear and so they aimed their barrels and shot at what was later revealed to be a tent harboring a couple that was making love. They killed the woman and during trial, the jurors found it difficult to understand their perceptual problems because they could not imagine how a yellow tent seemed like a growling bear.  Prior conditioning altered their perception and the perpetrator received a negligent homicide judgment (Loftus & Ketcham, 1991).

People do not see what they sense, rather they see what they think they sense. In this light, a witness perceives not the raw data of the event, rather, an interpretation of the raw data. There is an unconscious information processing process that interprets and discards the raw data or information (Norretranders, 1999). It presents an interpretation of the event. It is the reason why different witnesses of a similar event perceive it differently because their interpretation is subject to their unique information processing process based on their world view. The perception process only encodes the information that one thinks is expected. A witness also perceives events selectively based on prior life experiences. This conditioning may cause witnesses in good faith to fill gaps in perception depending on what is expected or wanted to perceive. Their perception leads them to give accounts that differ from what really happened.

Perception occurs through the senses and the perceived sensations are processed. For instance, research shows that most people would perceive a smaller light in the dark  as being further away than the larger light  even when in reality they are on the same distance from the eyes (Moses, 2001). All the information that a witness presents is first and foremost perceived. It is because nothing sticks in the mind unless it is perceived.  Processing the perceived sensations thus heavily depends on how one makes inferences. Engaging in inferential reasoning covers the gaps in actual perception. Witnesses may thus infer things they do not know from other things that they do know. It leads them to give an account that differs from what really happened. For instance, a witness may infer that the person they see carrying a stolen wallet is the one that robbed them (Moses, 2001).

Witnesses can only remember what they perceive and can perceive only what they attend to. Perception is influenced by a combination of stimulus that one already knows, expects or wants. Perception of events is a momentary and personal occurrence and once complete, the witness relies on memory.  Perception can be flawed because the brain is filled with one’s interpretation rather than the actual sensory information. A witness may thus have an altered perception that distorts memory based on inherent expectations at the acquisition stage of memory. A witness may interpret visual sensory information based on their inherent expectations, pre-existing knowledge or wants and thus an account that starkly differs from what really happened (Loftus & Ketcham, 1991).

Stressful situations also interfere with detailed perception. It is because heightened stress levels narrows the scope of perception and elevates emotions. Physiologically, stress affects the hippocampus, impairing the formation of memories. In this event, stress makes an impression on the person making perception unreliable.  The impact of a life threatening situation such as rape thus makes a witnesses’ perception unreliable. It makes the retrieval process unreliable as well and it may be the reason their account may differ from what really happened (Moses, 2001).


For the most part, matters involving eyewitness’s memory rely on the accuracy of long term memory rather than sensory and short term memory. Sensory memory stores information that lasts for the split second of an event because sensory organs only store information for less than a second in its unprocessed form. Individuals preserve information from their sensory systems in its sensory form. Short term memory allows one to store acquired memory for some seconds to minutes (Weiten, 2005). Short term memory stores limited items and when rehearsed and elaborated, it is registered and can be moved to the long term memory. Long term memory retains information that can last a lifetime.  Witnesses recount an event by retrieving information from the long-term memory (Hagsand, 2014).

Long term memory is divided into implicit and explicit memory. Implicit memory stores information that one does not unconsciously know like peddling a bike or a neonate’s lurch on a mother’s breast. Explicit memory stores information that one can verbalize consciously. Witnesses draw on their both their semantic and autobiographical aspects of their explicit memory.  Semantic memory contains facts such as people’s names and it is more about what one knows than recalling. Autobiographical memory contains a recollection of events and episodes. When one draws on the autobiographical memory, they recall the exact details of uttered words, and the elements in the environment (Green, 2013).

One of the reasons why a witness’ account may differ from what really happened is a faulty memory acquisition process. It is whereby one may not have perceived some information in the acquisition phase. When someone fails to effectively perceive information it affects their capacity to develop a comprehensive account of what really happened. It is also likely that the retention process was interfered with or even that information may be inaccessible during the retrieval process (Loftus, 1979).

Witnesses retrieve bits and pieces of their memories as a puzzle. Memory is thus a reconstruction of past events rather than a recording.  A witness often has insufficient information in the memory and h as to invoke pieces of information from other sources during the reconstruction process.  They draw from pre-existing schemas that are the stereotyped models of events and objects (Green, 2013). A witness’ account is thus susceptible to being altered because a lawyer’s questioning may alter the testament when fragments of the memory is unknowingly combined with information provided during questioning (Arkwotitz & Lilienfeld, January).

It is also likely that a witness may confuse the sources of information. For instance one may present imagined memories of imagined events rather than of an actual event. Memory source confusion may also incorporate information that is subsequently gained from other witnesses or read in newspapers, information from ones’ general knowledge. The witness may thus pool memory separate occurrences or mistake imaginative events for real ones. The witness may thus give information that differs from what really happened owing to the poor ability to determine the source of information (Green, 2013).

It is also evident that a witness may give an account that differs from the real occurrence because the retrieved information is subjected to subjective interpretation. Every witness interprets events based on personal beliefs, experiences and needs and world view. It is the reason different eyewitnesses observing the same event have different interpretations and different memories.  They store their unique perception or interpretation of events in their memory. More reason a witness’ account differs from what really happened is because memory changes with time. In recalling an event over and over, a witness drops details from earlier versions and adds new details to later versions. They may also incorporate information learnt after the event combining two memories into one (Green, 2013).

Forgetting is also responsible for why a witness’ account may differ what really happened. When a memory remains inactive for months or days, the physiological bases of memory tend to change. The memory trace in the brain or the engram gradually decays. Disuse decreases the amount of information that can be recalled and items of information in memory become less accessible with increased time. The loss of information occurs rapidly at first and is then followed by a leveling off.  Research shows that basic level information decays less rapidly than more fine detailed information. A study indicated that eye witnesses’ reports provided after 40 days are less detailed than those provided immediately after the event (Read & Connolly, 2006).

Retrieving an item from a memory also increases the likelihood that it is recalled again. In a forensic context, once witnesses make an immediate recall attempt, it preserves their subsequent recall performance making memory loss unlikely. It is because retrieval strengthens the associations between them and increases their representation in memory (Read & Connolly, 2006).

A witness may also give an account that differs from what really happened due to retrieval enhanced suggestibility. Witnesses may fall into repeated retrieval when providing testimony to police investigators, lawyers, friends and family members and it negatively influences their ability to resist subsequently misleading information (Chan & LaPaglia, 2011). Providing a witness with misleading information produces higher confidence for the incorrect information than for the correct information.  It may occur because initial retrieval may inadvertently draw attention to particular aspects of the event that was witnessed. Attention increases when new information regarding those particular items is presented and in the subsequent retrievals, the misinformation – new information is integrated into the memory becoming more memorable. Repeated retrieval can only lead to accurate recall when the questions are asked in an open ended and neutral way. However, when one receives misleading information, it increases suggestibility (Chan & LaPaglia, 2011). Engaging witnesses in frequent retrieval with misleading information may thus influence their tendency to provide information that differs from what really happened.


Indeed memories can be altered during retelling because people rarely retell memories in a neutral way. A witness’ testimony has a pivotal influence on the determination of guilt or innocence about the defendant. Mentally fit and healthy witnesses with good faith can provide an account that differs from what really happened due to a flawed perception and negative influences on their long-term memory. Perception occurs through the senses and witnesses can only remember what they perceive and can perceive only what they attend to.  Their perception is again influenced by ones environmental conditions and internal conditioning. Environmental conditions at the time of the event also significantly influence the witness’ capacity to for quality perception. Elevated emotions interfere with the hippocampus ability to register the entirety of the event. It means that a witness’s perception can alter their account based on personal interpretation and stress levels. A witness’ account may also differ due to impaired memory acquisition, external influences during memory reconstruction, confusion of sources of memory, forgetfulness, subjective interpretation, delays in retrieval and misinformation during repeated retrieval. These factors are pertinent in assessing the reliability of witnesses’ testimony particularly because memory is continuously altered and reconstructed.


Arkwotitz, H., & Lilienfeld, S. O. (January, 8 2009). Why Science Tells Us Not to Rely on Eyewitness Accounts. Retrieved October 15, 2014, from Scientific American:

Braddeley, A. (2004). Your Memory: A User’s Guide . Richmond Hill, Canada: Firefly Books.

Chan, J. C., & LaPaglia, J. A. (2011). The Dark side of Testing Memory: Repeated Retrieval can Enhance Eyewitness Suggestibility. Journal of Experimental Psychology, 8(29), 1-15.

Green, M. (2013). Eyewitness Memory is Unreliable. Retrieved October 15, 2014, from

Hagsand, A. (2014). Alcohol-Intoxicated Eyewitnesses’ Memory. Gothenburg, Sweden: University of Gothenburg.

Loftus, E. F. (1979). Eyewitness Testimony. Massachusetts: Harvard University Press.

Loftus, E., & Ketcham, K. (1991). Witness for the Defense: The Accused, the Eyewitness, and the Expert who Puts Memory on Trial. New York : St. Martins Press.

Moses, R. (2001). Misidentification: The Caprices of Eyewitness Testimony in Criminal Cases. Retrieved October 15, 2014, from criminal defence:

Norretranders, T. (1999). The User Illusion: Cutting Consciousness Down To Size. New York: Penguin Books.

Read, J. D., & Connolly, D. A. (2006). The Effects of Delay on Long Term Memory for Witnessed Events. In M. P. Toglia, D. Ross, J. Read, & R. C. Lindsay, Handbook of Eyewitness Psychology: Volume 1: Memory for Events (pp. 117-155). Mahway NJ: Lawrence Erlbaum Associates Inc.

Weiten, W. (2005). Psychology: Theme and Variations, The United States of America. New York: Thompson Learning Inc.

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