3.2 Memory - Learning and Memory

MCAT Behavioral Sciences Review - Kaplan Test Prep 2021–2022

3.2 Memory
Learning and Memory

LEARNING OBJECTIVES

After Chapter 3.2, you will be able to:

· Order the three modes of encoding from strongest to weakest

· Distinguish between maintenance rehearsal and elaborative rehearsal

· Predict how learning environments may impact recall

· Describe factors and phenomena that can lead to flaws in memory

· Define each type of human memory:

Image

While learning is mostly concerned with behavior, the study of memory focuses on how we gain the knowledge that we accumulate over our lifetimes. The formation of memories can be divided into three major processes: encoding, storage, and retrieval.

ENCODING

Encoding refers to the process of putting new information into memory. Information gained without any effort is the result of automatic processing. This type of cognitive processing is unintentional, and information is passively absorbed from the environment. As you walk down the street, you are constantly bombarded with information that seeps into your brain: you notice the temperature; you keep track of the route that you’re taking; you might stop at a coffee shop and realize that the same barista has been working each day this week.

There are, however, times when we must actively work to gain information. In studying for the MCAT, for example, you may create flashcards to memorize the enzymes of digestion or the functions of endocrine hormones. This active memorization is known as controlled (effortful) processing.

MCAT Expertise

Do not allow yourself to study for the MCAT using automatic processing! Just reading the text “to get through it” won’t cut it for the MCAT. Engage with the text: fill out the MCAT Concept Checks, write notes in the margins, ask yourself questions. Scientific studies of learning have demonstrated, time and time again, that controlled processing improves comprehension, retention, and speed and accuracy on Test Day.

With practice, controlled processing can become automatic. Think back to a time when you were learning a foreign language. At first, each word required a great deal of processing to decipher: you had to hear the word and consciously translate it into your native language in order to understand what was being said. This process took an amount of time and effort that was probably difficult to maintain for prolonged periods. However, as you gained more experience with the language, this process became easier until you may have been able to understand those same words intuitively, without having to think very hard about them at all. At that point, this skill that once required controlled processing became automatic.

There are a few different ways that we encode the meaning of information when controlled processing is required. We can visualize information (visual encoding), store the way it sounds (acoustic encoding), link it to knowledge that is already in memory (elaborative encoding), or put it into a meaningful context (semantic encoding). Of these, semantic encoding is the strongest and visual encoding is the weakest. When using semantic encoding, the more vivid the context, the better. In fact, we tend to recall information best when we can put it into the context of our own lives, a phenomenon called the self-reference effect.

Real World

The purpose of the Real World sidebars in your MCAT Review books is semantic encoding: by putting content into a meaningful context, retention of the information is improved. Most of our Real World sidebars are related to medicine because of the self-reference effect.

Of course, grouping information into a meaningful context is only one trick that we can use to aid in encoding. Another such aid is maintenance rehearsal, which is the repetition of a piece of information to either keep it within working memory (to prevent forgetting) or to store it in short-term and eventually long-term memory—topics discussed in the next section.

Mnemonics are another common way to memorize information, particularly lists. As you’ve seen in your Kaplan study materials, mnemonics are often acronyms or rhyming phrases that provide a vivid organization of the information we are trying to remember. Two other mnemonic techniques are commonly employed by memory experts. The method of loci involves associating each item in a list with a location along a route through a building that has already been memorized. For example, in memorizing a grocery list, someone might picture a carton of eggs sitting on their doorstep, a person spilling milk in the front hallway, a giant stick of butter in the living room, and so on. Later, when the person wishes to recall the list, they simply take a mental walk through the locations and recall the images they formed earlier. Similarly, the peg-word system associates numbers with items that rhyme with or resemble the numbers. For example, one might be associated with the sun, two with a shoe, three with a tree, and so on. As groundwork, the individual memorizes their personal peg-list. When another list needs to be memorized, the individual can simply pair each item in the list with their peg-list. In this example, the individual may visualize eggs being fried by the sun (1), a pair of shoes (2) filled with milk, and a tree (3) with leaves made of butter. Because of the serial nature of both the method-of-loci and peg-word systems, they are very useful for memorizing large lists of objects in order.

REAL World

Many feats of memory are accomplished via mnemonic techniques. In fact, the method of loci is a favorite among participants in the World Memory Championships.

Finally, chunking (sometimes referred to as clustering) is a memory trick that involves taking individual elements of a large list and grouping them together into groups of elements with related meaning. For example, consider the following list of 16 letters: E-N-A-L-P-K-C-U-R-T-R-A-C-S-U-B. Memorizing the list in order by rote might prove difficult until we realize that we can reverse the items and group them into meaningful chunks: BUS, CAR, TRUCK, PLANE.

STORAGE

Following encoding, information must be stored if it is to be remembered. There are several types of memory storage.

Sensory Memory

The first and most fleeting kind of memory storage is sensory memory, which preserves information in its original sensory form (auditory, visual, etc.) with high accuracy and lasts only a very short time, generally less than one second. Sensory memory consists of both iconic memory (fast-decaying memory of visual stimuli) and echoic memory (fast-decaying memory of auditory stimuli). Sensory memories are maintained by the major projection areas of each sensory system, such as the occipital lobe for vision and the temporal lobe for hearing. Of course, sensory memory fades very quickly, so unless the information is attended to, it will be lost.

MCAT Expertise

Sensory memory theoretically encompasses all five major senses, but studies have been mostly limited to sight, hearing, and touch (haptic memory).

The nature of sensory memory can be demonstrated experimentally. Consider the following procedure: a research participant is presented with a three-by-three array of letters, such as that presented in Figure 3.5, that is flashed onto a screen for a mere fraction of a second. When asked to list all of the letters she saw, the participant is able to correctly identify three or four (a procedure known as whole-report). However, when asked to list the letters of a particular row immediately after the presentation of the stimulus (known as partial-report), she can do so with 100 percent accuracy, no matter which row is chosen. This is iconic memory in action: in the time it takes to list out a few of the items, the entire list fades; yet it is clear that all of the letters do make their way into iconic memory because any small subset can be recalled at will.

ImageFigure 3.5. A Sample 3-by-3 Array for Studying Sensory Memory

MCAT Expertise

Eidetic memory refers to the ability to recall, with high precision, an image after only a brief exposure. It is hypothesized that eidetic memory represents an extreme example of iconic memory that endures for a few minutes. Although generally not observed in adults, it is reported to occur in a small percentage of children.

Short-Term Memory

Of course, we do pay attention to some of the information that we are exposed to, and that information enters our short-term memory. Similar to sensory memory, short-term memory fades quickly, over the course of approximately 30 seconds without rehearsal. In addition to having a limited duration, the number of items we can hold in our short-term memory at any given time, our memory capacity, is limited to approximately seven items, usually stated as the 7 ± 2 rule. As discussed in the previous section, the capacity of short-term memory can be increased by clustering information, and the duration can be extended using maintenance rehearsal. Short-term memory is housed primarily in the hippocampus, which is also responsible for the consolidation of short-term memory into long-term memory.

Working Memory

Working memory is closely related to short-term memory and is similarly supported by the hippocampus. It enables us to keep a few pieces of information in our consciousness simultaneously and to manipulate that information. To do this, one must integrate short-term memory, attention, and executive function; accordingly, the frontal and parietal lobes are also involved. This is the form of memory that allows us to do simple math in our heads.

Real World

Have you ever looked at a picture of a simple unfinished puzzle, and been able to fit the pieces together mentally? This skill is explained by one of the major theories that underlies working memory, which includes the concept of a visuospatial sketchpad. The visuospatial sketchpad was proposed by Baddeley and Hitch as part of their three-part working memory model along with the other two components they proposed: the central executive and the phonological loop. The visuospatial sketchpad explains our ability to not only store visual and spatial information, but to manipulate it as well.

Behavioral Sciences Guided Example With Expert Thinking

Passage

Expert Thinking

A musical melody is a series of tones played in succession that form a coherent musical idea. Melodies can be played in many different keys: absolute pitch of each of the notes changes as one changes keys, but as long as the relative pitches remain the same, the melody should still be recognizable. For example, the familiar melody of the song “Happy Birthday” should sound the same regardless of whether the first note is a C, an F, or a B-flat. While most people cannot name the key of a piece of music just by listening to it, they might still implicitly remember the way it "is supposed to sound" such that they could distinguish between the same melody played in different keys.

The passage provides the definition of melody, and the difference between absolute and relative pitch. Helpful if I'm not a musician, but really just setting the stage for the experiment.

Researchers interested in musical memory conducted an experiment with three groups of participants: 7- to 8-year-olds, 9- to 11-year-olds, and adults. Twenty-four British and Irish folk melodies were selected to be used as stimuli. The researchers expected that because these melodies share the sorts of patterns that are common in Western music, they should thereby be recognizable as melodies rather than simply a series of tones. It was also expected that these melodies were uncommon enough to be unfamiliar to the participants prior to the beginning of the study.

Setup: Three groups, two children, one adult, presented with melodies. The melodies were intended to be unfamiliar.

IV: age

In the exposure phase, participants were presented with twelve of the twenty-four melodies to listen to. In the recognition phase, all twenty-four melodies were presented. Of the melodies that were presented in the exposure phase, six were then presented in the recognition phase transposed to a higher or lower key. Participants were asked to rate whether each melody they heard in the recognition phase had been presented in the exposure phase, and rated this recognition on a scale from 1 (“definitely new”) to 6 (“definitely heard before”).

Finally, the description of the procedure. I'll want to parse this carefully. In the second phase, some melodies were heard earlier and some weren't. Some of those that have been heard before were presented in a different key.

Second IV: transposition

DV: recognition

To eliminate bias, researchers used an Area Under the Curve (AUC) score, which measures the relative difference in recognition rather than the absolute difference. If all of the recognition scores for old melodies are higher than the recognition scores for new melodies for a given participant, the AUC score is 1.0, which represents perfect discrimination. A score of 0.5 represents chance performance, such that the old and new melodies are indistinguishable.

I've never heard of an AUC score before, but the passage explains it. I'll probably need this to interpret the results.

Image

Figure 1 Mean AUC score for each group

IV: age and transposition

DV: recognition (AUC)


Higher AUC means better recognition, so it looks like people get better as they get older. It also seems people were slightly worse at recognizing the transposed melodies.

Adapted from: Schellenberg EG, Poon J, Weiss MW (2017) Memory for melody and key in childhood. PLoS ONE 12(10): e0187115. https://doi.org/10.1371/journal.pone.0187115

What do these results suggest about between-group and within-group trends with respect to explicit and implicit memory for music?

To answer this question, we’re going to have to make use of the results of this study, but we'll also have to recall and apply content knowledge from outside this passage. The prompt asks about differences in explicit and implicit memory, so we’ll want to start by figuring out how these terms apply in this general context, then apply these ideas specifically to the experiment. For the MCAT, we should know that explicit and implicit memory are both subdivisions of long-term memory. Explicit memory is the encoding of facts, and particularly relevant to the present study is episodic memory, the kind of explicit memory that involves experiences. The question “have I heard this melody before?” is answered by accessing an explicit memory. The relevance of implicit memory is more difficult here, since we typically think of implicit memories as procedural, involving skills and conditioned responses. Whenever we're not sure of how a concept in a question is related to the passage, we should go back to the passage and search for clues. The passage does provide a clue: in the first paragraph, the author describes the memory of the key of a melody as implicit rather than explicit. Now that we know what we’re looking for, we can examine the results of the study with these concepts, and the way in which they relate to the passage, already in mind.

The AUC score system used by the researchers might be unfamiliar, but the concept isn’t that much different from what we might normally see in a study like this one. A score of 0.5 represents random chance, and a score higher than that means that the participants were able to distinguish the melodies they’d heard from the ones they hadn’t. The higher the score, the better the recognition. From the figure, we can see two trends: as participants get older, recognition gets better, but when the melody is transposed, recognition gets worse for all participants by approximately the same amount.

We must apply the memory vocabulary words to these trends. We can conclude from these results that explicit memory for music improved by age across groups. Further, within each group, implicit memory did play a significant role in recognition, because melodies that matched those heard earlier explicitly but not implicitly (i.e., they were the same melody but transposed to a different key) were less readily recognized. The role of implicit memory on recognition seems to be consistent between groups.

Long-Term Memory

With enough rehearsal, information moves from short-term to long-term memory, an essentially limitless warehouse for knowledge that we are then able to recall on demand, sometimes for the rest of our lives. One of the ways that information is consolidated into long-term memory is elaborative rehearsal. Unlike maintenance rehearsal, which is simply a way of keeping the information at the forefront of consciousness, elaborative rehearsal is the association of the information to knowledge already stored in long-term memory. Elaborative rehearsal is closely tied to the self-reference effect noted earlier; those ideas that we are able to relate to our own lives are more likely to find their way into our long-term memory. While long-term memory is primarily controlled by the hippocampus, it should be noted that memories are moved, over time, back to the cerebral cortex. Thus, very long-term memories—our names and birthdates, the faces of our parents—are generally not affected by damage to the hippocampus.

There are two types of long-term memory. Implicit memory (also called nondeclarative memory) consists of our skills, habits, and conditioned responses, none of which need to be consciously recalled. Implicit memory includes procedural memory, which relates to our unconscious memory of the skills required to complete procedural tasks, and priming, which involves the presentation of one stimulus affecting perception of a second. Positive priming occurs when exposure to the first stimulus improves processing of the second stimulus, as demonstrated by measures such as decreased response time or decreased error rate. Conversely, in negative priming the first stimulus interferes with the processing of the second stimulus, resulting in slower response times and more errors.

Explicit memory (also called declarative memory) consists of those memories that require conscious recall. Explicit memory can be further divided into episodic memory and semantic memory. Episodic memory refers to our recollection of life experiences. By contrast, semantic memory refers to ideas, concepts, or facts that we know, but are not tied to specific life experiences. Autobiographical memory is the name given to our explicit memories about our lives and ourselves, and includes all of our episodic memories of our own life experiences, but also includes semantic memories that relate to our personal traits and characteristics. Interestingly, memory disorders can affect one type of memory but leave others alone. For example, a patient with amnesia might not remember the time he learned to ride a bicycle (episodic memory) or the names of the parts of a bicycle (semantic memory), but he may, to his surprise, retain the skill of riding a bicycle when given one (procedural memory). The various major categories of memory are summarized in Figure 3.6.

MCAT Expertise

Although semantic and episodic memory are differentiated and can be separate, they can also co-occur. One type of explicit memory with components of both episodic and semantic memory is flashbulb memory, which is the detailed recollection of stimuli immediately surrounding an important (or emotionally arousing) event. Flashbulb memory helps you answer the question "Do you remember where you were when…?"

ImageFigure 3.6. Types of Memory

RETRIEVAL

Of course, memories that are stored are of no use unless we can pull them back out to use them. Retrieval is the name given to the process of demonstrating that something that has been learned has been retained. Most people think about retrieval in terms of recall, or the retrieval and statement of previously learned information, but learning can be additionally demonstrated by recognizing or quickly relearning information.

Recognition, the process of merely identifying a piece of information that was previously learned, is far easier than recall. This difference is something you can take advantage of because the MCAT, as a multiple-choice test, is largely based on recognizing information. If the MCAT were a fill-in-the-blank style exam, your approach to studying would have to be vastly different and far more in-depth.

Real World

Think back to elementary school. How many of your classmates do you think you could list? Chances are, not many. On the other hand, glancing through your class photo, you would probably recognize the vast majority of your former classmates. This gap is the difference between recall and recognition.

Relearning is another way of demonstrating that information has been stored in long-term memory. In studying the memorization of lists, Hermann Ebbinghaus found that his recall of a list of short words he had learned the previous day was often quite poor. However, he was able to rememorize the list much more quickly the second time through. Ebbinghaus interpreted this to mean that the information had been stored, even though it wasn’t readily available for recall. Through additional research, he discovered that the longer the amount of time between sessions of relearning, the greater the retention of the information later on. Ebbinghaus dubbed this phenomenon the spacing effect, and it helps to explain why cramming is not nearly as effective as spacing out studying over an extended period of time.

Recalling a fact at a moment’s notice can be difficult. Fortunately, the brain has ways of organizing information so that it can take advantage of environmental cues to tell it where to find a given memory. Psychologists think of memory not as simply a stockpile of unrelated facts, but rather as a network of interconnected ideas. The brain organizes ideas into a semantic network, as shown in Figure 3.7, in which concepts are linked together based on similar meaning, not unlike an Internet encyclopedia wherein each page includes links for similar topics. For example, the concept of red might be closely linked to other colors, like orange and green, as well as objects, like fire engine and roses. When one node of our semantic network is activated, such as seeing the word red on a sign, the other linked concepts around it are also unconsciously activated, a process known as spreading activation. Spreading activation is at the heart of the previously mentioned positive priming, as recall is aided by first being presented with a word or phrase, a recall cue, that is close to the desired semantic memory.

ImageFigure 3.7. An Example Semantic NetworkIn spreading activation, the concept of red will also unconsciously activate other linked concepts.

Another common retrieval cue is context effect, where memory is aided by being in the physical location where encoding took place. Psychologists have shown a person will score better when they take an exam in the same room in which they learned the information. Context effects can go even further than this; facts learned underwater are better recalled when underwater than when on land. Similarly, source monitoring is a part of the retrieval process that involves determining the origin of memories, and whether they are factual (real and accurate) or fictional (from a dream, novel, or movie).

A person’s mental state can also affect their ability to recall. State-dependent memory, alternately referred to as a state-dependent effect, is a retrieval cue based on performing better when in the same mental state as when the information was learned. People who learn facts or skills while intoxicated, for example, will show better recall or proficiency when performing those same tasks while intoxicated as compared to performing them while sober. Emotions work in a similar way: being in a foul mood primes negative memories, which in turn work to sustain the foul mood. So not only will memory be better for information learned when in a similar mood, but recall of negative or positive memories will lead to the persistence of the mood.

Finally, studies on list memorization have indicated that an item's position in the list affected his ability to recall, which he termed the serial-position effect. When researchers give participants a list of items to memorize, the participants have much higher recall for both the first few and last few items on the list. The tendency to remember early and late items in the list is known as the primacy and recency effect, respectively. However, when asked to remember the list later, people show strong recall for the first few items while recall of the last few items fades. Psychologists interpret this to mean that the recency effect is a result of the last items still being in short-term memory on initial recall.

FORGETTING

Unfortunately, even long-term memory is not always permanent. Several phenomena can result in amnesia, a significant loss of memorized information. The inability to remember where, when, or how one has obtained knowledge is called source amnesia.

Brain Disorders

There are several disorders that can lead to decline in memory. The most common is Alzheimer’s disease, which is a degenerative brain disorder thought to be linked to a loss of acetylcholine in neurons that link to the hippocampus, although its exact causes are not well understood. Alzheimer’s is marked by progressive dementia (a loss of cognitive function) and memory loss, with atrophy of the brain, as shown in Figure 3.8. While not perfectly linear, memory loss in Alzheimer’s disease tends to proceed in a retrograde fashion, with loss of recent memories before distant memories. Microscopic findings of Alzheimer’s include neurofibrillary tangles and β-amyloid plaques. One common phenomenon that occurs in individuals with middle- to late-stage Alzheimer’s is sundowning, an increase in dysfunction in the late afternoon and evening.

ImageFigure 3.8. Findings of Alzheimer’s Disease

Bridge

The β-amyloid plaques of Alzheimer’s disease are incorrectly folded copies of the amyloid precursor protein, in which insoluble β-pleated sheets form and then deposit in the brain. Protein folding is discussed in detail in Chapter 1 of MCAT Biochemistry Review.

Korsakoff’s syndrome is another form of memory loss caused by thiamine deficiency in the brain. The disorder is marked by both retrograde amnesia (the loss of previously formed memories) and anterograde amnesia (the inability to form new memories). Another common symptom is confabulation, or the process of creating vivid but fabricated memories, typically thought to be an attempt made by the brain to fill in the gaps of missing memories.

Agnosia is the loss of the ability to recognize objects, people, or sounds, though usually only one of the three. Agnosia is usually caused by physical damage to the brain, such as that caused by a stroke or a neurological disorder such as multiple sclerosis.

Decay

Of course, not all memory loss is due to a disorder. Through a process known as decay, memories are simply lost naturally over time as the neurochemical trace of a short-term memory fades. In his word memorization experiment, Ebbinghaus noted what he called a “curve of forgetting", formally called the retention function, as shown in Figure 3.9. For a day or two after learning the list, recall fell sharply but then leveled off.

ImageFigure 3.9. Ebbinghaus’s Curve of Forgetting

Interference

Another common reason for memory loss is interference (also referred to as an interference effect), a retrieval error caused by the existence of other, usually similar, information. Interference can be classified by its direction. When we experience proactive interference, old information is interfering with new learning. For example, think back to a time when you moved to a new address. For a short time, you may have had trouble recalling individual pieces of the new address because you were so used to the old one. Similarly, Ebbinghaus found that with each successive list he learned, his recall for new lists decreased over time, an effect he attributed to interference caused by older lists.

Retroactive interference is when new information causes forgetting of old information. For example, at the beginning of a school year, teachers learning a new set of students’ names often find that they can no longer remember the names of the previous year’s students. One way of preventing retroactive interference is to reduce the number of interfering events, which is why it is often best to study in the evening about an hour before falling asleep (although this also depends on your personal style!).

Aging and Memory

Contrary to popular belief, aging does not necessarily lead to significant memory loss; while there are many individuals whose memory fades in old age, this is not always the case. In fact, studies show that there is a larger range of memory ability for 70-year-olds than there is for 20-year-olds. There are, however, some trends that can be demonstrated when evaluating the memories of older individuals. When asked about the most pivotal events in their lives, people in their 70s and 80s tend to say that their most vivid memories are of events that occurred in their teens and 20s, a fact that psychologists interpret to mean that this time is a peak period for encoding in a person’s life.

Even for the elderly, certain types of memory remain quite strong. People tend not to demonstrate much degeneration in recognition or skill-based memory as they age. Even certain types of recall will remain strong for most people; semantically meaningful material can be easily learned and recalled, most likely due to older individuals having a larger semantic network than their younger counterparts. Prospective memory (remembering to perform a task at some point in the future) remains mostly intact when it is event-based—that is, primed by a trigger event, such as remembering to buy milk when walking past the grocery store. On the other hand, time-based prospective memory, such as remembering to take a medication every day at 7:00 a.m., does tend to decline with age.

MEMORY RECONSTRUCTION

We often think of memory as a record of our experiences or a kind of video recording that is stored to be accessed later; this accurate recall of past events is defined as reproductive memory. Nothing could be further from the truth. Reconstructive memory is a theory of memory recall in which cognitive processes such as imagination, semantic memory, and perception affect the act of remembering. This theory explains how two people can recall the same event as occurring in completely different ways. A memory that incorrectly recalls actual events or recalls events that never occurred is known as a false memory. Despite their unsettling nature, false memories are common and are to be expected when we consider the many factors that can affect memory. Most memories are encoded with little detail, only focusing on the details deemed important in the moment. Also, as previously discussed, if a person repeatedly rehearses the memory in their mind, then that person may fill in missing details with unreliable information. Repressed memories, memories stored in the unconscious mind and blocked from recall, have also been a topic of controversy. Some psychologists believe repressed memories can be brought back into our conscious mind either spontaneously or through psychotherapy. Such memories are called recovered memories. However, it is not possible to distinguish between false memories and recovered memories without evidence and some research psychologists believe psychotherapy is more likely to lead to the creation of false memories. So, the act of recalling a memory can result in the production of a false memory.

False memory production is not only limited to internal factors. Memories can also be affected by outside sources as well. In a famous experiment, participants were shown several pictures including one picture of a car stopped at a yield sign. Later, these participants were presented with written descriptions of the pictures, and some of these descriptions contained misinformation, such as a description of a car stopped at a stop sign. When asked to recall the details of the pictures, many participants insisted they had seen a stop sign in the picture. This example illustrates the misinformation effect, where a person's recall of an event becomes less accurate due to the injection of outside information into the memory.

The misinformation effect can also be seen at the point of recall. In another experiment, participants were shown a video of an automobile accident. Some participants were then asked, How fast were the cars moving when they collided?, while others were asked about the accident using more descriptive language such as How fast were the cars moving when they crashed? Those participants who were asked the question with leading language were much more likely to overstate the severity of the accident than those who had been asked the question with less descriptive language.

Intrusion errors refers to false memories that have included a false detail into a particular memory. This is similar to the misinformation effect but distinct in that the intrusion error is not from an outside source. Instead, the intruding memory is injected into original memory due to both memories being related or sharing a theme. Upon memory recall, the brain incorrectly associates the intruding memory with the source memory, leading to a false memory. For example, if over the years you’ve attended multiple New Year’s Eve celebrations in two different cities, then your memories of the two cities are linked. A possible intrusion error could be recalling that a particular restaurant is located in Vancouver, because you recall eating at the restaurant on New Year’s Eve and celebrating New Year’s Eve in Vancouver. However, the restaurant is really in Toronto, where you have also celebrated on New Year’s.

Source-monitoring error involves confusion between semantic and episodic memory: a person remembers the details of an event, but confuses the context under which those details were gained. Source-monitoring error often manifests when a person hears a story of something that happened to someone else, and later recalls the story as having happened to him- or herself.

Real World

During a Congressional Medal of Honor ceremony in 1983, Ronald Reagan relayed a vivid story about a heroic World War II pilot who received a posthumous medal. Skeptical reporters, unaware of any incident matching the details of Reagan’s story, checked into the story and found that the pilot had existed—in the 1944 movie A Wing and a Prayer. Reagan had remembered the details of the pilot’s heroic actions but had forgotten their source.

MCAT Concept Check 3.2:

Before you move on, assess your understanding of the material with these questions.

1. List the three modes in which information can be encoded, from strongest to weakest.

1.

2.

3.

2. In what ways is maintenance rehearsal different from elaborative rehearsal?

3. In terms of recall, why might it be a bad idea to study for the MCAT while listening to music?

4. What are some factors that might cause eyewitness courtroom testimony to be unreliable?