4 – Le funzioni della mente: La memoria umana

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1 4 – Le funzioni della mente: La memoria umana
Introduzione generale alla memoria

2 Memoria È un processo attraverso il quale l’informazione è: Acquisita
Codifica Immagazzinata nel cervello Ritenzione Recuperata Richiamo o riconoscimento In certi casi dimenticata Oblio/amnesia Our memory is the process by which information is retained for later use. The basic process by which information is processed follows this format: information is acquired and encoded, which leads to storage in the brain, which leads to the possibility of later retrieval (though as you know at test time, is not a guarantee), and the possibility of eventually forgetting the information. Today, cognitive psychologists like to compare the human mind to a computer and memory to an information-processing system. I think you can appreciate the analogy. Your PC acquires (or receives) input from a keyboard or a mouse; it converts the symbols into a special numeric code; it saves the information on a hard drive, CD, or disk; it then retrieves the data from the disk to be displayed on a screen or sends it to a printer. If the computer crashes, if there’s not enough space on the disk, if the file was deleted, or if you enter the wrong retrieval command, the information becomes inaccessible, or ‘forgotten’.

3 Modello di Memoria come Information-Processing
Il computer come un modello della nostra memoria Tre tipi di memoria Memoria sensoriale Memoria a breve termine (MBT) Memoria a lungo termine (MLT) Può mantenere una vasta quantità di informazione per diversi anni. Using the computer as a model, memory researchers seek to trace the flow of information as it is mental processed. In this information-processing model, a stimulus that registers on our senses can be remembered only if it 1. Draws attention, which brings it into consciousness; 2. Is encoded, or transferred to storage sites in the brain, and 3. Is retrieved for use at a later time. Within this information-processing memory approach, three types of memory have been distinguished: sensory, short-term and long-term. Sensory memory stores all stimuli that register on the senses, holding literal copies for a brief moment ranging from a fraction of a second to three seconds. Sensations that do not draw attention tend to vanish, but those we ‘notice’ are transferred to short-term memory , another temporary storage system that can hold seven or so items of information for about 20 seconds. Although STM fades quickly, information can be held for a longer period of time through repetition and rehearsal. When people talk about attention span, they are referring to short-term memory. Finally, long-term memory is a somewhat permanent storage system that can hold vast quantities of information for many years. Science writer Isaac Asimov once estimated that LTM takes in a quadrillion separate bits of information in the course of a lifetime. Mathematician John Griffith estimated that, from birth to death, the average person stores five hundred times more information than the Encyclopedia Britannica. When people talk about memory, long-term memory is typically what they have in mind. We’ll talk about each of these in a little more detail later on.

4 Modello di Memoria di Atkinson e Shiffrin
Recupero Stimolo Memoria sensoriale MBT MLT Attenzione Codifica Perdita Perdita Perdita Many events register in sensory memory. Those that are noticed are briefly stored in short-term memory; those that are encoded are transferred to a more permanent facility. As shown forgetting may be caused by failures of attention, encoding, or retrieval. Note, however, that this is only a model and does NOT mean that the brain has three separate storage bins. This is only one view of how memory works. There is a radically different view. Most computers process instructions in fixed sequence, one linear step at a time. In contrast, the human brain performs multiple operations simultaneously, ‘in parallel’. Thus, some cognitive psychologists have rejected the information-processing model in favor of parallel-processing models in which knowledge is represented in a web-like network of connections among thousands of interacting ‘processing units’ all active at once. The two main questions we’ll be asking ourselves throughout this chapter are: How are memories stored? And to what extend are our memories of the past faithful to reality?

5 Memoria sensoriale Immagazzina tutti gli stimoli che sono registrati dai sensi Dura fino a 3 secondi Tre tipi Memoria iconica Visiva In genere dura circa 0,3 secondi Test di Sperling (1960s) Memoria ecoica Uditiva In genere dura circa 3 secondi Memoria aptica Tattile Stimolo Sensoriale Memoria sensoriale Take a flashlight into a dark room, turn it on, shine it on a wall, and wave it quickly in a circular motion. What do you see? If you twirl it fast enough, the light will appear to leave a glowing trail, and you’ll see a continuous circle. The reason: Even though the light illuminates only one point in the circle at a time, your visual system stores a ‘snapshot’ of watch point as you watch the next point. The visual image is called an icon, and the snapshot it stores is called iconic memory. People typically don’t realize that a fleeting mental trace lingers after a stimulus is removed from view. Nor did cognitive psychologists realize it until George Sperling’s ingenious series of experiments.

6 Esperimento di Sperling
Presentava una matrice di lettere per 50 ms Riferire il maggior numero di lettere I soggetti ricordavano solo la metà delle lettere Forse dipendeva dal fatto che i soggetti avevano poco tempo per vedere l’intera matrice? No Come dimostrò questo Sperling? Sperling instructed subjects to stare at the center of a blank screen. Then he flashed an array of the letters for 1/20 of a second and asked subjects to name as many of the letters as possible. Try it for yourself. You’ll probably recall about a a handful of letters. In fact, Sperling found that no matter how large the array was, subjects could name only four or five items. Why? One possibility is that people can register just so much visual input in a single glance – that twelve letters is too much to see in so little time. A second possibility is that all letters registered by the image faded before subjects could report them all. Indeed, many subjects insisted that they were able to ‘see’ the whole array but then forgot some of the letters before they could name them. Did the information that was lost leave a momentary trace, as subjects had claimed, or did it never register in the first place? To test these alternative hypotheses, Sperling devised the ‘partial-report technique’. Instead of asking subjects to list all the letters, he asked them to name only one row in each array – a row that was not determined until after the array was shown. In this procedure, each presentation was immediately followed by a tone signaling which letters to name: A high-pitched tone indicated the top line; a medium pitch, the middle line; a low pitch, the bottom line.

7 Esperimento di Sperling sulla memoria iconica
1. Le lettere sono mostrate su uno schermo per 50ms

8 Esperimento di Sperling sulla memoria iconica
2. Lo schermo è bianco

9 Esperimento di Sperling sulla memoria iconica
La durata del tempo varia fino a un secondo 3. È emesso un suono che indica la riga

10 Esperimento di Sperling sulla memoria iconica
4. Il soggetto riporta le lettere nella riga indicata dal suono

11 Esperimento di Sperling sulla memoria iconica
Un suono basso, medio o alto è emesso immediatamente dopo che la matrice è scomparsa. Il tono segnalava 1 riga da riportare Il richiamo era quasi perfetto La memoria delle immagini si sfoca dopo circa 300 ms, rendendo il riportare l’intera immagine difficile da fare. High Medium Low If the saw the entire array, subjects should have been able to report all the letters in a prompted row correctly – regardless of which row was prompted. Sperling was right: subjects correctly recalled 3 letters per row. In other words, all 9 letters, not 4 or 5, were instantly registered in consciousness before fading, held briefly in iconic memory. To determine how long this type of memory lasts, Sperling next varied the time between the letters and the tone that signaled the row to be recalled. He found that the visual image started to fade as the interval was increased to 1/3 of a second and had almost completely vanished 2/3 of a second later. Since this study, researchers have found when it comes to pictures of objects or scenes, words, sentences, and other visual stimuli briefly presented, people form ‘fleeting memories’ that last for just a fraction of a second. Not an afterimage because Sperling showed he could present the letters to one eye and influence the memory by presenting a bright flash to the other eye. This would not have worked if the visual information was stored on the retina.

12 Memoria sensoriale Memoria ecoica
La memoria sensoriale di stimoli uditivi dura solo da 2 a 3 secondi Perché abbiamo bisogno di una memoria sensoriale? A similar phenomenon exists for auditory stimuli. The next time you listen to the radio, notice after you turn it off how an ‘echo’ of the sound seems to reverberate inside your head. This auditory sensory register is called echoic memory. Just how much auditory input is stored in echoic memory? In a study modeled after Sperling’s, Christopher Darwin and others (1972) put headphones on subjects and all at once played three sets of spoken letters – in the right ear, in the left ear, and in both ears at once. Subjects then received a visual signal indicating which set to report. Using this study and others, researchers have found that echoic memory holds only a few items but lasts for two or three seconds, and perhaps even longer, before activation in the auditory cortex fades. Whether a sensory memory system stores information for one-third of a second or for three seconds, you might wonder: What’s the point of having a ‘memory’ that is so quick to decay? To answer this question, try to imagine what your perceptions of the world would be like without sensory memories. Without the visual icon, for instance, you would lose track of what you see with every blink of the eye – as if you were viewing the world through a series of snapshots rather than on a continuous film. Similarly, it would be hard to understand spoken language without the persistent traces of echoic memory. Speech would be heard as a series of staccato sounds rather than as connected words and phrases. In fact, we have other sensory memories as well – for touch, smell, and taste stimuli.

13 Memoria a breve termine
Funzione Processamento conscio dell’informazione L’attenzione è la chiave I limiti di quale informazione viene sotto il cono di luce della memoria a breve termine a ogni dato momento Anche conosciuta come memoria di lavoro (MDL) Think about what your environment is like as you walk from class to class on campus. You’re seeing people, trees, buildings, trash. You’re hearing multitudes of conversations, the sounds of cars as they drive past, the sounds of leaves as they fall. You’re smelling the car exhaust, the perfume of the girl next to you, the flowers that are blooming, and a pungent trash can that you walk past. More stimuli is probably reaching your sensors than you can think or write about, but most never reach your consciousness and are immediately ‘forgotten’. The key is attention. As we talked about earlier, sensations that do not capture our attention quickly tend to evaporate, whereas those we notice are transferred to short-term memory – a somewhat more lasting but limited storage facility. As we saw in the ‘Sensation and Perception’ chapter, people are selective in their perceptions and can instantly direct their attention to stimuli that are interesting, adaptive, or important. From the sensory register, the brain encodes information – that is, it converts it into a form that can be stored in short-term memory. A stimulus may be encoded in different ways. After you read a sentence from a book, you might recall a picture of the letters and their placement on the page (visual encoding), the sounds of the words themselves (acoustic encoding), or the meaning of the sentence as a whole (semantic encoding). Research shows that people typically encode this type of information in acoustic terms. Thus, when subjects are presented with a string of letters and immediately asked to recall them, the make more ‘sound-alike’ errors than ‘look-alike’ errors. For example, subjects mis-recall an ‘F’ as an ‘S’ or ‘X’, but not as an ‘E’ or ‘B’. Subjects are also more likely to confuse words that sounds alike (man, can) than words that are similar in meaning (big, huge) – further indicating that we tend to encode verbal information in acoustic terms rather than in semantic terms. Memoria Sensoriale MDL o MBT Attenzione Stimolo sensoriale

14 Memoria a breve termine
Memorizzate la seguente lista di numeri:

15 Memoria a breve termine
Trascrivete i numeri in ordine.

16 Memoria a breve termine
Ora, riprovate…

17 Memoria a breve termine
Capacità limitata Può mantenere 7 ± 2 item per circa 20 secondi Reiterazione L’uso della ripetizione favorisce il mantenimento dell’informazione nella MBT CHUNK Unità significativa di informazione Senza reiterazione noi ricordiamo 4 ± 2 chunk Con la reiterazione noi ricordiamo 7 ± 2 chunk Ericsson & Chase (1982) It’s important to note that to the extent that one stimulus captures our attention, others may be ignored – sometimes with startling effects on memory. For example, research on eyewitness testimony shows that when a criminal displays a weapon, witnesses are less able to identify the culprit than if no weapon is present. Why? One reason is that the witness’s eyes fixate on the weapon, particularly when it comes as a surprise, thereby drawing attention away from the face. To demonstrate, researchers showed subjects slides of a customer who walked up to a bank teller and pulled out either a gun or a checkbook. By recording eye movements, these researchers found that subjects spent more time looking at the gun than at the checkbook. The result: impairment in their ability to identify the criminal in a lineup. Limited by attentional resources, short-term memory can hold a small number of items. How small an number? The average person can store seven or so items – regardless of whether they are numbers, letters, words, or names. Okay, so short-term memory can accommodate only seven items, and that number may be smaller, but here’s the hitch: Although an item may consist of one letter or digit, these items can be grouped into chunks of words, sentences, and large numbers – thus enabling us to use our storage capacity more efficiently. The activity we did at the start of this section demonstrates the effects of chunking – you were better able to remember more numbers when they were chunked into significant years than when they appeared to be random numbers. Chunking enables us to improve our short-term memory span by using our capacity more efficiently. You may be limited to seven or so chunks, but you can learn to increase the size of those chunks. Without rehearsal, some researchers find that people can only remember about 4 plus or minus 2 chunks. With rehearsal, we’re back to the magic seven plus or minus two. But with serious training, people can increase the size of the chunks so that you are remembering large quantities of material. To demonstrate, a group of researchers trained two male university students, both long-distance runners and of average intelligence, for several months. For an hour a day, three or four days a week, these students were asked to recall random strings of numbers. If they recalled a sequence correctly, another digit was added to the next sequence and the task was repeated. If they made a mistake, the number of digits in the next sequence was reduced by one. Before practicing, their memory span was four to seven digits. After six months, they were up to eighty items. In one session, for example, the experimenter read the following numbers in order: After two minutes of concentration, the subject repeated all seventy-three digits, in groups of three and four. How did he do it? Given no special instructions, the subject developed his own elaborate strategy: he converted the random numbers into ages, dates, and racing times. Thus, 893 became 89.3 (a very old person); 1944 became 1944 (near the end of the second world war); and 3492 became 3 minutes and 49.2 seconds (nearly a world’s record for the mile).

18 Memoria a lungo termine
Una volta che l’informazione passa dalla MS alla MBT essa può essere codificata nella MLT Recupero Codifica MS Attenzione ML o MBT MLT Stimolo Sensoriale

19 Memoria a lungo termine – Codifica
Reiterazione elaborativa Una tecnica per trasferire informazione nella MLT è pensare ad essa in un modo più profondo Livelli di processamento Semantico è più efficace che il processamento visuale o acustico Craik & Tulving (1975) Effetto auto riferito Una nuova informazione rilevante per sé stessi è più piena e più facile da richiamare. Do you remember your fourth birthday, the name of your first-grade teacher, or the smell of floor wax in the corridors of your elementary school? Can you describe a dream that you had last night or recite the words of the national anthem? To answer these questions, you would have to retrieve information from the mental warehouse of long-term memory. Like the hard drive on a computer, long-term memory is a relatively enduring storage system that has the capacity to retain vast amounts of information for long periods of time. We’ll examine long-term memories of the recent and remote past – how they are encoded, stored, retrieved, forgotten, and even reconstructed in the course of a lifetime. Information can be kept alive in short-term working memory by rote repetition or maintenance rehearsal. But to transfer something into long-term memory, you would find it much more effective to use elaborative rehearsal – a strategy that involves thinking about the material in a more meaningful way and associating it with other knowledge that is already in long-term memory. The more deeply you process something, the more likely you are to recall it at a later time. To demonstrate this process, Craik & Tulving (1975) showed a subject a list of words, one at a time, and for each asked them for 1) a simple visual judgment that required no thought about the words themselves (Is the word printed in capital letters?); 2) an acoustic judgment that required subjects to at least pronounce the letters as words (Does the word rhyme with smell?); or 3) a more complex semantic judgment that compelled subjects to think about the meaning of the words (Does the word fit the sentence ‘I saw a blank in the pond’?). Subjects did not realize that their memory would be tested later. Yet words that were processed at a ‘deep’ level, in terms of meaning, were more easily recognized than those processed at a ‘shallow’ level. Does making complex semantic judgments, compared to simple visual judgments, activate different regions of the brain? Is it possible to see physical traces of deep processing? Using functional MRI technology, researchers devised a study similar to the Craik & Tulving study where subjects were shown stimulus words on a computer and were instructed to determine whether the words were concrete or abstract (a semantic judgment) or simply whether they were printed in uppercase or lowercase letters (a visual judgment). As in past research, subjects later recalled more words for which they made semantic rather than visual judgments. In addition, however, the brain-imaging measures showed that processing the words in semantic terms triggered more activity in a part of the frontal cortex of the language-dominant left hemisphere. Perhaps the most effective form of elaborative rehearsal is the linking of new information to the self. In one study, subjects sat in front of a microcomputer and looked at forty trait words (for example, shy, friendly, ambitious). In some cases, they were told to judge whether the words were self-descriptive; in others, they judged the word’s length, sound, or meaning. When asked to list as many of the words as they could, subjects remembered more after thinking about the words in reference to themselves than for other purposes. Apparently, the self can be used as a memory aid: By viewing new information as relevant to ourselves, we consider that information more fully and organize it around common themes. The result is an improvement in recall. Hence, why I tell you guys to try and personalize this material as much as possible, even if it is just coming up with examples of when these things have happened to you…it increases your likelihood of remembering it for the exam. Although the transfer of information to long-term memory often requires a great deal of thought and effort, certain types of information are encoded automatically and without conscious control. When you meet someone for the first time, you may have trouble remembering their name but you can easily recall their face. Similarly, people encode information about time, spatial locations, and event frequencies without conscious effort.

20 Memoria a lungo termine
Procedurale (implicita) Memorie di comportamenti, abilità, ecc. Dimostrata attraverso il comportamento Dichiarativa (esplicita) Memorie di fatti Episodica – esperienze personali legate a luoghi e tempi Semantica – conoscenza generale Network semantico It seems that we have more than one type of long-term memory. Researchers now commonly distinguish two types of memory. One is procedural memory, a ‘know how’ memory that consists of our stored knowledge of well-learned habits and skills – such as how to drive, swim, type, ride a bike, and the tie shoelaces. The second type is declarative memory, which consists of both semantic memories for facts about the world – such as who Michael Jordan is, what a dollar is worth, what you need to access the World Wide Web, and what the word ‘gravity’ means – and episodic memories that we have about ourselves – such as who our parents are, where we went to school, and what our favorite movie is. The distinction is important because people with amnesia are often unable to recall declarative memories of facts and events, yet they still retain many of the skills they had learned and committed to procedural memory. With all that’s stored in long-term memory – habits, skills, verbal information and knowledge of the words, names, dates, faces, pictures, personal experiences, and the like – it’s amazing that anything can ever be retrieved from this vast warehouse. Surely our knowledge must be organized in memory, perhaps the way books are filed in a library. One popular view is that memories are stored in a complex web of associations, or semantic networks. According to proponents of this view, items in memory are linked together by semantic relationships. When one item is brought to mind, the pathways leading to meaningfully related items are primed – thus increasing the likelihood that they too will be retrieved. A good deal of research supports the notion that memories are stored in semantic networks. When subjects are given a list of sixty words that fall into four categories (animals, professions, names, and fruits) – even if the words are presented in a mixed order – subjects later tend to recall them in clusters. In other words, retreiving tiger is more likely to trigger one’s memory for baboon than for dentist, Jason, or banana.

21 Network sematico

22 Recupero Recupero Memoria esplicita Memoria implicita
Processo che controlla il flusso di informazioni dal magazzino della MLT alla MDL Memoria esplicita I tipi di memoria prodotti attraverso il recupero conscio di ricordi in risposta a questioni dirette. Memoria implicita Un ricordo non conscio di una precedente esperienza che è rivelata indirettamente dai suoi effetti sull’azione. Once information is stored, how do you know it exists? Because people can openly report their recollections, this seems like a silly question. In fact, however, this is one of the thorniest questions confronting cognitive psychologists. Hermann Ebbinghaus was not only the first person to study memory systematically but also the first to realize that a memory may exist without awareness. In his words “These experiences remain concealed from consciousness and yet produce an effect which is significant and which authenticates their previous experience.” Memory without awareness illustrates how human beings can be both competent and incompetent at the same time, and it poses a profound challenge to the researcher: If people have memories they cannot report, how can we ever know these memories exist? To his credit, Ebbinghaus devised a simple but clever technique. He tested memory by its effect on performance. Acting as his own subject, he would learn a set of nonsense syllables and then count the number of trials it later took him to relearn the same list. If it took fewer trials the second time around than the first, then he must have retained some of the material – even if he could not consciously recite it. In recent years, other techniques have been devised. Basically, there are two types of tests, and each assesses a different type of memory; one explicit, the other implicit. Explicit memory is a term used to describe the recollections of facts and events that people try to retrieve in response to direct questions. In contrast, implicit memory is a term used to describe the retention of information without awareness, as measured by its indirect effects. Why is this distinction important? The reason, as we’ll see, is that people often exhibit dissociations between the two types of tasks. That is, people will consciously forget (have no explicit memory) of that experience. There are different ways to interpret this pattern. Some psychologists believe that explicit and implicit memory are separate systems that are controlled by different parts of the brain, whereas others believe that the dissociations merely indicate differences in the way information is encoded and retrieved. Either way, it’s useful to consider these two aspects of memory separately.

23 Recupero – Memoria esplicita
Test del richiamo libero Un tipo di compito di memoria esplicita nel quale una persona deve riprodurre dell’informazione senza il beneficio di indizi esterni. Compito di riconoscimento Una forma di recupero di memoria esplicita nel quale gli item sono presentati alla persona che deve stabilire se essi erano stati precedentemente incontrati. Fallimento nel recupero Sulla punta della lingua (Brown & McNeill) Okay, can you all name all of Walt Disney’s Seven Dwarfs? Try it. When I was put to the test, I could only name about four…I always forget about Bashful, Sneezy, and Happy! This type of task, in which a person is asked to reproduce information without the benefit of external cues, is an example of a free-recall test of explicit memory. Other examples include taking an essay exam, describing a criminal’s face to the police, and struggling to recall a childhood experience. Now if I had given you a list of ten possible dwarf names and asked you to indicate which of them are accurate, that would have been a recognition task. This task requires you to select a remembered item from a list of alternatives. So are taking a multiple-choice exam and picking a criminal from a lineup, or identifying photographs from a family album. Research shows that recall and recognition are both forms of explicit memory in that people are consciously trying to retrieve the information. There is, however, a key difference: People tend to perform better at recognition. The seven dwarfs task illustrates the point. When college students were asked to recall the characters on their own, they correctly produced an average of 69% of the names. Yet, when they made selections from a list, the accuracy rate increased to 86%. The fact that recognition is easier than recall tells us that forgetting sometimes occurs not because memory has decayed or because we didn’t encode the information but because the information is difficult to reclaim from storage. Retrieval failure is a common experience. Have you ever felt as thought a word or name you were trying to recall was just out of reach – on the tip of your tongue? In a classic study of the tip-of-the-tongue phenomenon, Brown & McNeill prompted this experience by giving students definitions of uncommon words and asking them to produce the words themselves. For example, what is ‘the green-colored matter found in plants’? And what is ‘the art of speaking in such a way that the voice seems to come from another place’? Most often, subjects either knew the word right away or were certain that they did not know it. But at times, subjects knew they word but could not recall it – a frustrating state that they likened to being on the brink of a sneeze. The experience is an interesting one. When a word is on the tip of the tongue, subjects often come up with other words that are similar in sound or meaning. Groping for chlorophyll, subjects might say chlorine or cholesterol. For ventroliquism, they produce words such as ventilate or vernacular. In fact, a surprising number of people will guess the correct first letter, last letter, and number of syllables contained in the missing word. Recognition is often easier than recall because recognition tasks contain retrieval cues, or reminders. A retrieval cue is a stimulus that helps us to access information in long-term memory. Any stimulus that is encoded along with an experience can later trigger one’s memory of that experience. The retrieval cue may be a picture, a location, a word, a song, another person, or even a fragrance or the mood we’re in.

24 Recupero – Memoria esplicita
Memoria contesto-dipendente Abbiamo più successo nel recuperare dei contenuti di memoria se ci troviamo nello stesso ambiente nel quale li abbiamo immagazzinati. Memoria stato-dipendente Abbiamo più successo nel recuperare dei contenuti di memoria se ci troviamo nello stesso stato d’animo (umore) nel quale li abbiamo immagazzinati. This principle that any stimulus encoded along with an experience can later jog one’s memory of that experience led to an interesting notion that memory is ‘context dependent’ – that people find it easier to retrieve information from memory when they’re in the same situation in which the information was obtained in the first place. In an unusual initial test of this hypothesis, researchers presented scuba divers with a list of words in one of two settings: fifteen underwater or on the beach. Then they tested the divers in the same setting or in the other setting. Illustrating context-dependent memory, the divers recalled 40% more words when the material was learned and retrieved in the same context. This type of research has uncovered several applicable findings for you all: because test-taking situations are typically quiet, you recall more information if you also study in a quiet setting. There’s no doubt about it, we can often jog a memory by reinstating the initial context of an experience. This explains why, when you walk into a room to get something and then completely forget why you went into the room – you can often re-remember the object of your task by going back into the room where you first thought of what you wanted. Internal cues that become associated with an event may also spark the retrieval of explicit memories. Illustrating the phenomenon of state-dependent memory, studies reveal that it is often easier to recall something when our state of mind is the same at testing as it was during encoding. If you have an experience when you are happy or sad, drunk or sober, calm or aroused, that experience – unless your emotional state is intensely distracting – is more likely to pop to mind or be free-recalled when your internal state later is the same than when it’s different. Researchers have found that the reason it helps to be memory-tested in the same place where you learned the material is that the environment is likely to transport you back to the same mood state – and it’s this mood state that serves as a retrieval cue. When it comes to internal states and memory, there is a complicating factor: The mood we’re in often leads us to evoke memories that are congruent with that mood. When people are happy, the good times are easier to recall. But when people are sad, depressed, or anxious, their minds become flooded with negative events of the past. Currently depressed people thus report having more intrusive memories of death and other bad experiences compared to nondepressed controls. You can see how destructive this cycle can get.

25 Recupero – Memoria implicita
Mostrare di conoscere qualcosa senza riconoscere che la conosciamo Ricerche con amnesici Déjà vu L’illusione che una nuova situazione ci è familiare Testimonianza oculare Transfert della testimonianza oculare Plagio involontario With implicit memory – we’re really examining the fact that we show knowledge of something without being able to ‘know’ and recognize that we know it. Early researchers believed that amnesics lacked the ability to encode or store information in long-term memory. They believed that they could still perform ‘skills’ – but could not keep new ‘information’ in memory. Or could they?? Several case studies have shown that while amnesics may not be aware or conscious of the fact that they have learned a skill or set of information, they test higher than do people who have not been exposed to the stimulus. For example, one amnesic was asked to be interviewed in a room where they had taken part in a number of experiments. The amnesic agreed but stated that he would have to be shown where the room was…except that he had already turned in the right direction and walked right to it with no help. This dissociation – the tendency for amnsesics to show signs of long-term retention of information without awareness – has now been amply observed in studies involving different types of amnesia and different implicit-memory tests. For example, researchers tried to classically condition to an anterograde amnesia patient by pairing a harmless tone with electric shock. Although the patient could not later recall these sessions, he reacted with greater arousal whenever the tone was presented. You don’t have to suffer brain damage or drug-induced amnesia to exhibit a dissociation between memory and awareness. Have you ever had the eerie feeling that you’ve been in a situation before, even though you had not? Déjà vu is defined as the illusion that a new situation is familiar. In a way, déjà vu is the opposite of amnesia. Whereas amnesics have memories without awareness or familiarity, the person with déjà vu has a sense of familiarity but no real memory. Estimates vary, but between 30 and 96% of people report having had such an episode. Déjà vu is not the only type of association that is commonly experienced. Retention without awareness occurs in all of us – sometimes with interesting consequences. Retention without awareness can also have serious consequences. Several years ago, psychologist Donald Thompson was falsely accused of rape on the basis of the victim’s recollection. Luckily for Thompson, he was being interviewed lived on television as the rape occurred – an interview, ironically, on the subject of human memory. Apparently, the victim was watching Thompson’s show just before being attacked and then mistook him for the rapist. Was Thompson familiar to her? Yes, he was – but from the TV show, not from the crime scene. Thanks to his airtight alibi, Thompson was instantly vindicated. Perhaps others have not been so fortunate. The problem illustrated by this story is that sometimes witnesses remember a face but forget the circumstances in which they saw it. In one study, subjects witnessed a staged crime and then looked through mug shots. A few days later, they were asked to view a lineup. The result was startling: Subjects were as likely to identify an innocent person whose photograph was in the mug shots as they were to pick the actual criminal. This familiarity effect gives rise to the phenomenon of eyewitness transference, whereby a person seen in one situation is later confused in memory, or ‘transferred’, to another situation – often with tragic consequences. Unconscious transference occurs when we are aware that something is familiar but we cannot pinpoint the correct source of that familiarity. In other words, the experience has an impact on behavior, but without our conscious awareness. There is another possible repercussion of implicit memory: unintentional plagiarism. In 2002, two popular historians and authors, the late Stephen Ambrose and Doris Kearns Goodwin were accused of lifting passages without quotation from other sources. Most of the sources were credited in footnotes, and both authors said the omission of quotation marks around the borrowed material was inadvertent, the unconscious result of careless record-keeping. Have you ever had an insight you thought was original, only later to realize or be told that it was ‘borrowed’ from another source? Are people who write, compose music, solve problems, tell jokes, or think up creative ideas vulnerable to unintentional plagiarism? Researchers had subjects in groups take turns generating items that fit a particular category (sports, four-legged animals, musical instruments, and clothing). After four rounds, they asked subjects individually to recall the items that they personally had generated and to come up with new ones from the same categories. As it turned out, 75% of the subjects took credit for at least one item of someone else’s, and 71% came up with a ‘new’ item that was given earlier. Some subjects inadvertently plagiarized their own ideas, but most often they ‘stole’ from others in the group. Additional research has shown that people are vulnerable to unintentional plagiarism in some situations more than others. Predictably, the problem is more likely to occur when the ideas taken are highly memorable, when the person who gave the original ideas has status, when the original ideas were shared in anonymous group situations, when subjects were distracted or in a hurry or not overly concerned about the origin of their ideas, and after a long period of time has elapsed. These studies show that there is a bit of amnesia in all of us. Commenting on the amount of unconscious plagiarism exhibited by research participants in the lab, psychologists speculate that the problem is a lot more common than anybody would realize.

26 Oblio If we remembered everything, we should on most occasions be as ill off as if we remembered nothing. William James Mancanza di codifica Spesso noi non codifichiamo le caratteristiche necessarie a “ricordare” un oggetto/evento Decadimento Le tracce mnestiche tendono a decadere con il tempo? Non è più una teoria valida dell’oblio Jenkins & Dallenbach (1924) Now before we celebrate the virtues of memory and outline the techniques we can use to improve it, let’s stop and ponder the wisdom of William James (you’ll remember him as one of our founding fathers of psychology) who said ‘If we remembered everything, we should on most occasions be as ill off as if we remembered nothing.” James was right. Sometimes it is better to forget – which is why some psychologists have suggested the paradoxical conclusion that forgetting is an adaptive, economical aspect of human memory. Memory failure is a common experience in everyday life. Why? Do memory traces fade with time? Are they displaced by newer memories? Or do memories get buried, perhaps blocked by unconscious forces? As we’ll see, forgetting can result from one of four processes: a lack of encoding, decay, interference, or repression. In the first two, the forgotten information is simply not in long-term memory storage. In the second two, the memory may exist, but it is difficult, if not impossible, to retrieve. Do you know what an American penny looks like? Would you recognize one if you say it? If you were born in the US, you have looked at, held, and counted thousands of pennies in your life. Yet many people cannot accurately draw one from memory, name its features, or distinguish it from a fake. Look at these coins. Which of these is the true penny? When researchers present this task to college students, they find that about 58% did not identify the right coin. The reason for this result is not that the subjects forgot what a penny looks like – it’s that the features were never encoded into long-term memory. And why should they be? So long as you can tell the difference between pennies and other coins, there is no need to attend to the fine details. The penny is not the only common, everyday object whose features we fail to notice. People also have difficulty recalling the features of a dollar bill, computer keyboard, the front-page spread of their favorite newspaper, and even the layout of a telephone – objects we look at and use all the time. The oldest theory of forgetting is that memory traces erode with the passage of time. But there are two problems with this simple explanation. One is that there is no physiological evidence of decay that corresponds to the fading of memory. The second is that time alone is not the most critical factor. Memory for newly learned nonsense syllables fades in a matter of hours, but the foreign language learned in high school is retained for many years. The key blow to the decay theory of forgetting was landed in 1924 by John Jenkins and Karl Dallenbach. Day after day, these researchers presented nonsense syllables to two subjects and then tested their memory after one, two, four, or eight hours. On some days, the subjects went to sleep between learning and testing; on other days, they stayed awake and kept busy. The subjects recalled more items after they had slept than when they were awake and involved in other activities. Jenkins & Dallenbach concluded that ‘forgetting is not so much a matter of decay of old impressions and associations as it is a matter of interference, inhibition, or obliteration of the old by the new.’ To minimize forgetting, you may find it helpful to go to sleep shortly after studying, thus avoiding ‘new information’ interference.

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28 Interference theory L’oblio è il risultato del fatto che alcune memorie interferiscono con altre Interferenza proattiva Vecchie memorie interferiscono con la capacità di ricordare nuove memorie. Interferenza retroattiva Nuove memorie interferiscono con la capacità di ricordare vecchie memorie. L’interferenza è maggiore quando i contenuti di memoria sono simili. By showing that memory loss may be caused by mental activity that takes place when we are awake, Jenkins & Dallenbach’s study suggested a third explanation of forgetting – that something learned may be forgotten due to interference from other information. There are two kinds of interference. In proactive interference, prior information inhibits our ability to recall something new. If you try to learn a set of names, formulas, phone numbers, or glossary terms, you will find it more difficult if you had earlier studied a similar set of items. Many years ago, researchers found that the more nonsense-syllable experiments subjects had taken part in, the more forgetting they exhibited in a brand-new study. A related problem is retroactive interference, whereby new material disrupts memory for previously learned information. Thus, subjects in various experiments are at least temporarily less likely to recognize previously seen pictures of nature scenes, faces, and common objects if they are then exposed to similar photographs before being tested. One learning experience can displace – or at least inhibit – the retrieval of another. That is why, when people go back and review a subset of to-be-remembered information, their memory for nonreviewed material suffers.

29 Oblio Rimozione A volte siamo incapaci di ricordare eventi passati dolorosi Mentre non ci sono prove di laboratorio per questo, studi di casi suggeriscono che le memorie possono essere rimosse per un certo numero di anni e recuperate in terapia More than a hundred years ago, Freud observed that his patients often could not recall unpleasant past events from their own lives. In fact, he observed, they would sometimes stop, pull back, and lose their train of thought just as they seemed on the brink of an insight. Freud called this repression, and he said it was an unconscious defense mechanism that keeps painful personal memories under lock and key – and out of awareness. We’ll see later that people who suffer childhood traumas such as war, abuse, and rape sometimes develop ‘dissociative disorders’ characterized by apparent gaps in their explicit memory. Although repression has never been demonstrated in a laboratory setting, psychotherapy case studies suggest that memories can be repressed for long periods of time and recovered in therapy. As we’ll see later, however, it is difficult in actual cases to distinguish between dormant memories of actual past events and falsely constructed memories of experiences that never occurred.

30 La costruzione di memorie
Teoria dello schema Preconcetti sulle persone, oggetti o eventi che distorcono il modo in cui nuova informazione è interpretata e riordata. Effetto della disinformazione La tendenza a incorporare informazioni false post-evento nella propria memoria dell’evento stesso Ricordi illusori La gente a volte crea ricordi che sono completamente falsi Up to now, we have likened human memory to a computer that faithfully encodes, stores, and retrieves information from the recent and distant past. Clearly, however, there is more to the story. As we’ll see, remembering is an active process in which we reconstruct memories according to our beliefs, wishes, needs, and information received from outside sources. In 1932, Frederick Bartlett asked British college students to recall a story taken from the folklore of Native American culture. He found that although they correctly recalled the gist of the story, they changed, exaggerated, added, and omitted certain details – resulting in a narrative that was more coherent to them. Without realizing it, subjects reconstructed the material to fit their own schemas, a term that Bartlett used to describe the preconceptions that people have about persons and situations. It’s now clear that schemas distort memory, often by leading us to fill in missing pieces. Research by Intraub and others illustrates that point. In a series of studies, they showed people close-up photographs of various scenes – such as a telephone booth on a street corner, a basketball on a gym floor, and a lawn chair on a grassy field. Consistently, subjects who were later asked to recall these scenes mentally extended the borders by reporting or drawing details that were not in the pictures but might plausibly have existed outside the camera’s field of view. Why? It appears that the scenes activated perceptual schemas that led subjects over time to insert new details into memory. Memory is an active construction of the past – a construction that alters reality in ways that are consistent not only with prior expectations but also with postevent information. Consider the plight of those who witness street crimes. Afterward, they talk to each other, read about it in the newspapers, sometimes even watch coverage on television. By the time these witnesses are questioned by authorities, one wonders if their original memory is still ‘pure’, uncontaminated by postevent information. According to Elizabeth Loftus, it probably is not. Using her studies of eyewitness testimony, Loftus proposed a theory of reconstructive memory. After people observe an event, she said, later information about the event – whether it’s true or not – becomes integrated into the fabric of their memory. A classic study illustrates this misinformation effect. In that study, researchers presented subjects with a slide show in which a red car hits a pedestrian after turning at an intersection. Subjects saw either a stop sign or a yield sign in the slides, but then embedded in a series of questions they were asked was one that implied the presence of the other sign. The result: The number of subjects who later ‘recognized’ the slide with the wrong traffic sign increased from 25 to 59%. Other studies have confirmed this effect. This provocative theory has arouse controversy. Does misinformation permanently impair a witness’s real memory, never to be retrieved again? Or do subjects merely follow the experimenter’s ‘suggestions’, leaving a true memory intact for retrieval under other conditions? Either way, an important practical lesson remains: Whether witnesses’ memories are truly altered or not, their reports of what they remember are hopelessly biased by postevent information. The misinformation effect led cognitive psychologists to discover that people sometimes create memories that are completely false. People who have heard a list of sleep-related words (like bed or yawn) or music-related words (like jazz or instrument) were often convinced just minutes later that they had also heard sleep and music – words that fit but were not actually on the list. This result is easy to find – even if the test is delayed 24 hours, even when subjects are forewarned about the false memory effect.

31 Migliorare la memoria Tempo di pratica Profondità di lavorazione
Distribuire il vostro studio nel corso del tempo Profondità di lavorazione Trascorrere del tempo di studio di qualità Tecniche mnemoniche verbali Utilizzare rima o acronimi per ridurre la quantità di informazioni da memorizzare Over the years, psychologists have stumbled in a few rare individuals who seem equipped with extraordinary ‘hardware’ for memory. But often, the actors, waiters, and others who impress us with their extraordinary memories are ordinary people who use memory tricks called mnemonics. Can you too boost your recall capacity and improve your study skills by using mnemonics? Let’s consider the self-help implications of this chapter, many of which are described in paperbacks on how to improve your memory. To learn names, dates, vocabulary words, or the contexts in a textbook, you’ll find that practice makes perfect. In general, the more time spent studying, the better. Skimming or speed-reading will not promote long-term retention. In fact, it pays to overlearn – that is, to review the material even after you think you have it mastered. It also helps to distribute your studying over time rather than cram all at once. You will retain more information from four two-hour sessions that from one eight-hour marathon. The sheer amount of practice is important, but only if it’s ‘quality time’. Mindless drills may help maintain information in short-term memory, but long-term retention requires that you think actively and deeply about material – about what it means and how it is linked to what you already know. Sometimes the easiest way to remember a list of items is to use verbal mnemonics, or ‘memory tricks’. Chances are you have already used popular methods such as rhymes (I before E, except after C) and acronyms that reduce the amount of information to be stored (ROY G BIV).

32 Migliorare la memoria Tecnica dei loci Interferenza
Elementi da ricordare sono mentalmente collocati in luoghi familiari Interferenza Studio poco prima di dormire e rivedo tutto il materiale poco prima dell’esame Destinare un periodo ininterrotta di tempo per un solo corso Contesto reintegrazione Cercare di studiare nello stesso ambiente e stato d'animo in cui darai l’esame Most books on improving memory recommend that verbal information be represented as visual images. One popular use of imagery is the method of loci, in which items to be recalled are mentally placed in familiar locations. It works like this: First you memorize a series of objects along a familiar route. For example, you might imagine your morning walk from the bedroom, to the bathroom, visualize the objects you pass: your bed, then the bathroom door, shower, stairs, and so on. These places become pigeonholes for items to be recalled. To memorize a shopping list, for example, you could picture a dozen eggs lined up on the bed, a bag of red apples handing on the bathroom door, and butter in the soap dish of the shower. When you take a mental stroll through the house, the items on the list should pop to mind. The trick is to link new items to others already in memory. Because one learning experience can disrupt memory for another, you should guard against the effects of interference. This problem is common among students, as material learned in one course can make it harder to retain that learned in another. To minimize interference, follow two simple suggestions: First, study right before sleeping and review all the material right before the exam. Second, allocate an uninterrupted chunk of time to one course; then do the same for the others. If you study psychology, then move to biology, then go on to math and back to psychology, each course will disrupt your memory of the others – especially if the material is similar. Context reinstatement: Information is easier to recall when people are in the physical setting in which it was acquired – and in the same frame of mind. The setting and the mood it evokes serve as cues that trigger the retrieval of to-be-remembered information. That’s why actors like to rehearse on the stage where they will later perform. So next time you have an important exam to take, try to study in the room where you’ll take the test.