How Do We Retrieve Information from Memory?
What Is Memory Retrieval?
Memory Retrieval is the process in which information is taken out of storage. The process is related to memory encoding and storage in such a way that co-occurring information during encoding - like the way information is encoded, and how stored information is organized - serves as cues and aids for remembering. Memory retrieval is tricky because it is a process that is observed and evaluated based on the accuracy and reliability of its output. Memory researchers today are interested in memory retrieval, specifically reconstructive memory - the process in which people reconstruct stories and past events and conversations - and how it affects the validity of legal testimonies.
The Relationship Between Memory Encoding and Retrieval
Memory encoding and memory retrieval are distinct, yet interconnected, phases of memory. How we encode information affect how well we can remember them. The relationship between memory encoding and memory retrieval is shown with the serial position effect, priming, encoding specificity, and state- and context-dependent memory.
Serial Position Effect. The serial position effect is the tendency for items at the beginning and end of the list to be retrieved more readily. There are two aspects of the serial position effect - primacy and recency effects. The primacy effect is the tendency for items at the beginning of the list to be retrieved more readily, while the recency effect is the tendency for items at the end of the list to be retrieved more readily. Memory researchers explain that the primacy effect happens because information encoded earlier has more time and opportunity to be rehearsed and elaborated in short-term memory, has less competition in working memory, and has a higher chance of getting stored in long-term memory. On the other hand, the recency effect happens because information encoded later is still undergoing rehearsal in working memory, and is therefore readily available for recall. A good application of the serial position effect is in job hunting. Interviewees are advised to aim for the first and last spot during interviews.
Priming. Priming is the process of introducing information beforehand to aid in retrieval. For example, you are walking along a dark alley when you heard a scream from far away. Then you suddenly felt a hand land on your shoulder. Chances are you're going to scream too, and the reaction would be much faster than usual. Priming is also involved in some unintentional acts of plagiarism. For example, your friend proposed to you a good idea for your research project, but you dismissed it, because by that time you thought it was not at all good. After several weeks or months, you proposed the very same idea to your friend. Priming is also the culprit behind those embarrassing moments as when your friend tells you the exact same joke you told him months before. Priming, thus, leads to more accurate and faster memory retrieval.
Encoding Specificity. Encoding specificity states that irrelevant information at the time of encoding contributes to the distinctiveness of the encoded information, which may even be processed up to long-term memory. For example, while reading your favorite novel, you eyed at page 31 and flipped the page, and Bang! Was that a guns shot? Chances are you're going to remember both the number 31 and the gun shot for a longer period than when there was no bang heard.
State- and Context-Dependent Memory. How well we retrieve information is sometimes dependent on the context in which the information is encoded in memory. For example, Godden and Baddeley (1975) found that scuba divers recalled more when they are asked to recall at the same context or setting in which they learned. This is the reason why it could be helpful to study for a test in a similar setting where you will take the test. Another good application of context-dependent memory, as one professor advised his students, is to wear the same _perfume during study time and test-taking periods, or chew the same gum or candy flavor. How well we retrieve information is also sometimes dependent on our physical and emotional states during the time of encoding. This is the reason why we tend to remember past positive experiences when we are in a happy mood, and remember past negative experiences when we are in a bad mood. Sadly, this vicious cycle often perpetuates sadness in most people, which can then lead to depression. On a positive note, actors and actresses deliberately try to re-experience (remember) past negative experiences to force themselves in sad mood, especially in dramatic settings.
Using Retrieval Cues
Retrieval cues are mental or physical aids that can help you remember better and faster. For example, when trying to memorize the different parts of the brain, you can benefit from using an actual brain model with parts that can be disassembled and reassembled, so that you have with you visual, tactile, and even auditory sensations (if you identify each part out loud) as cues. At times when you are trying to remember the items that you needed to buy in grocery, because you forgot the list, the items in display can actually serve as retrieval cues. Lastly, the way information is stored in long-term memory is also vital in effective memory retrieval.
There are times when mental and physical cues are not readily available so that you have to generate them yourself. A good strategy is taking cues from hierarchies, associations, and schemas, which are the different ways in which information is organized in long-term memory. A popular Filipino game show is Pinoy Henyo (Genius Filipino), where a participant needs to guess the word placed on his forehead using some leading questions which a second participant (a partner) can answer only with "yes", "no", and "possibly, somewhat, or maybe" (which is "pwede" in Filipino language). Over the course of time, participants of the game show have developed good retrieval strategies for such words as names of cities, parts of the body, things, food, events, and even names of popular personalities. For example, in trying to guess "New York", a good strategy is to go through hierarchies of location - place, outside or inside the Philippines, continent, country, state or city. Associations would be useful in guessing the word "banana" - fruit, color, long or rounded; and schemas would be useful in trying to guess "Noynoy Aquino" - person, profession, etc.
Retrieval cues are specifically vital for prospective memory, which is memory for what we intentionally want to do in the future. Oftentimes, we forget the things that we need to do because of absentmindedness - because we are preoccupied with something else when we needed to do the task. Prospective memory has two components - timing (when the activity will be done) and content (the activity itself). It is also divided into two types: time-based and event-based. Time-based prospective memory uses time as cue for remembering the activity. For example, you may intend to watch a movie in HBO by 9:30 pm. Your cue for watching the movie is the time 9:30 pm. One the other hand, event-based prospective memory uses events as cue for the activity. Continuing from the example about the HBO movie, suppose you have an online group meeting scheduled the same day, from 8:30 pm to 9:30 pm. Instead of relying on the time, you may rely on that event (online group meeting) as cue to help you remember to watch the HBO movie. Generally, recall for event-based prospective memory is better than recall for time-based prospective memory.
The Retrieval Task
How well we remember also depends upon how much we are trying to remember, how deliberate the effort is to remember, and which aspects of long-term memory we are trying to remember.
Difference Between Recall and Recognition. Suppose someone who looks rather familiar waves "hello" to you, but you can't quite remember where you met him and what his name was. This illustrates the difference between recognition and recall. You recognize the stimulus, but can't name it. A multiple-choice test is also a lot easier than essay test, because the former only asks you to recognize among the available options the correct answer, while the latter asks you to recall the entire information from memory.
Tip-of-the-Tongue Phenomenon. The tip-of-the-tongue phenomenon is an effortful retrieval task that occurs when people are confident that they know something but can't quite pull it out of memory. Most of the time, those who experience this phenomenon remember the first letter and number of syllables of the word. If the missing information is a name, they try to point out the person's profession to successfully retrieve the name. If the missing information is a word, they then repeat aloud the initial letters and the number of syllables remembered. Memory researchers speculate that the tip-of-the-tongue phenomenon is due to some memory encoding problems, where only some portions of the information were stored in long-term memory. However, because those who experience it often are very confident of the available partial information that they have, most are successful in retrieving the information even if the information is not entirely stored in long-term memory. How that happens remains a mystery.
Retrieval of Episodic Memory. Episodic memory, or memory for events, has two types - prospective and retrospective episodic memory. Prospective memory, as introduced earlier, is memory for future events; while retrospective memory is memory for past events. Maylor, Chater and Brown (2001) found that we are better are recalling prospective than retrospective memory. Cherry and Lecompte (1999) and Einstein et al. (2000) found that younger adults have better prospective memory than older adults do.
One important aspect of retrospective memory is autobiographical memory, or memory for past experiences. Martin Conway and David Rubin (1993) observed that retrieval of autobiographical memory occurs in three different levels - according to life time periods, general events, and event-specific knowledge. Of the three levels, life time periods are the most abstract, occurring in long segments measured in years or decades. For example, you might describe your childhood days as filled with friends of different backgrounds. General events are extended composite episodes measured in days, weeks, or months; for example, a one-week vacation you had last month. Lastly, event-specific knowledge is composed of individual episodes measured in seconds, minutes, or hours; for example, your graduation ball or a high school reunion. According to Dan McAdams (1993), autobiographical memory is less about facts and more about meanings; that it connects the past and the present; and, that it forms the core of our personal identities.
Retrospective memory is also filled with emotions. Flashbulb memory is made of emotionally significant events that people often recall with more accuracy and vivid imagery than everyday events. Memory researchers speculate that its adaptive function is to fix details into long-term memory to be interpreted at a later time. Rubin and Kozin (1984) asked college students three of the most vivid memories in their lives. They found out that college students' flashbulb memory revolve around events involving injuries or accidents, sports, members of the opposite sex, animals, deaths, first week of college, and vacations. More than 50% of the participants reported accurately and vividly remembering a witnessed or experienced car accident, the first meeting with a college roommate, the night of high school graduation, an early romantic experience, speaking in front of an audience, receiving college admission letter, and the first romantic date. Rubin and Kozin (1984) suggests that flashbulb memory can also deteriorate, but that it is far more durable and accurate than other types of episodic memory, presumably because people often talk and think about it for days, weeks, or even after a few years, and that it is associated with emotions more strongly than any other types of episodic memory.
A type of flashbulb memory, called personal trauma, is memory for a strong negative emotional experience. According to William James, personal traumatic events are too emotionally arousing to leave a scar on the brain's tissue. Personal trauma can also deteriorate, but distortions only occur in the details and not at the core of the event. Inaccuracies in report may be due to perceptual errors caused by shock, some attempts to reduce anxiety, and incorporated discussions that influence reconstruction of one's own version of the event. Memory researchers speculate that memory for personal trauma is unlikely to be forgotten because of its strong association with the release of stress-related hormones signaled by the amygdala.
Personal trauma can lead to Post-Traumatic Stress Disorder (PTSD), symptoms of which may immediately follow the trauma or be delayed for months or even years. People with PTSD experience memory and concentration difficulties, and flashbacks (as if they relive the event) during nightmares or in awake but distracted state. Memory for personal trauma may also be repressed, or pushed into some inaccessible part of the conscious mind. Some psychologists point to repression as the reason why some cases of PTSD are delayed for a long period of time. According to psychodynamic psychologists, repression of traumatic events makes conscious remembering difficult in order to protect the individual from developing anxiety from threatening information.
Memory Retrieval and Eyewitness Testimonies
Accuracy in memory retrieval is often taken for granted in everyday life, but it is particularly serious for eyewitness testimony. This is because wrong statements have serious legal consequences - the wrong person may be put to jail or to death. According to Cutler and Penrod (1995), around 2,000 to 10,000 people are wrongly convicted in the US annually due to faulty eyewitness testimony. A recent estimate by Huff (2002) puts the number to 7,500 arrested for serious crimes and wrongfully convicted in the US. Some of the problems lawyers and judges face when evaluating eyewitness testimonies are report discrepancies, memory distortions, bias, and priming.
- Discrepancies. It is not uncommon that judges face conflicting testimonies from different people. What makes legal matters worse is that these people are often confident with what they remember, and cross-examinations reveal that all of them are actually telling the truth. For example, in the O.J. Simpson murder trial, Simpson's housekeeper testified that his white bronco did not move from its spot all evening, while his limousine driver testified not seeing the car late at night. Fortunately, Simpson and his white bronco were televised moving slowly along a Los Angeles freeway as he threatened suicide.
- Distortion. Memory fades in time. Shepard (1967) observed that accuracy for picture identification decreases in time - from 100% after a two-hour time lapse, to 57% after four months, only 7% higher than chance. Additionally, Loftus (1975) observed that retrospective memory could be altered by introducing new information, even if the information is in conflict with memory. She showed her research participants a film of an automobile accident, and afterwards, asked them how fast the white sports car was after it passed the barn (even if there was no barn shown in the film). Surprisingly, 17% of the participants answered, thinking that there was indeed a barn in the film.
- Bias, specifically, Cultural Bias. Behrman and Davey (2001) found that some ethnic groups are less likely able to perceive individual differences among another ethnic group. For example, Latinos have trouble distinguishing among several Asians. Loftus (1993) also found that people tend to blame crimes to one or more ethnic groups. In one experiment, she showed a mugging in a TV news program, which was followed by a lineup of six individuals, and TV viewers were urged to call and identify who the mugged is from the lineup. 90% of the callers identified the wrong person, and 33% of those identified an African American or Latino as the suspect.
- Priming. In the 2002 Washington, DC sniper attacks that killed ten people, the media unknowingly repeated in television a white van appearing near the earlier shootings, which prompted witnesses to remember white, instead of the actual blue, car seen in the last attack. Elizabeth Loftus (2003) also personally observed how witnesses immediately shared and influenced each other's thoughts after a shop robbery. Police now advises witnesses to write down what they have seen immediately after a crime to prevent primed contamination.
In an effort to filter false memories, Kassin et al. (2001) asked 64 forensic psychologists, who have both conducted eyewitness research and testified as expert witnesses, to evaluate thirty statements regarding eyewitness testimony. 90% or more of the experts agree that how questions are worded influence the outcome of testimonies (98%); the instructions during lineup affect the eyewitness' willingness to make an identification (98%); factors unrelated to the accuracy of identification can hammer down an eyewitness' confidence to his or her testimony (95%); prior exposure to mug shots primes eyewitnesses during lineup selection (95%); eyewitness testimonies almost always include post-event information (94%); children are vulnerable to social factors, such as suggestions from the interviewer and peer pressure (94%); the attitudes and expectations of eyewitnesses influence what and how they view and remember the situation (92%); hypnosis makes eyewitnesses suggestible to both leading and misleading questions (91%); alcohol intoxication impairs an eyewitness' ability to recall (91%); eyewitnesses can identify suspects of their own race more accurately (90%). On the other hand, 50% or less of the experts agree to the following statements: younger adults provide more accurate testimonies than older adults (50%); hypnosis increases the accuracy of a testimony (45%); accuracy of identification is related to how fast the identification is made (40%); trained observers, like police officers, are no better than the average person when it comes to making accurate testimonies 939%); violent events are less remembered than nonviolent events (37%); it is easy to distinguish true memories from false memories (32%); repressed, and consequently, recovered memories of traumatic events are reliable (22%).