Presentation on theme: "Memory Our memories may fail us sometimes, but they are essential for life as we currently experience it. Without memory, we would be lost in the present."— Presentation transcript:
6 The Three-Stage Model The Three-Stage Model Has guided research in memory since the late 1960sViews memory as composed of three relatively distinct stagesInformation from the physical environment enters the sensory registers through each of our senses (vision, hearing, taste, smell, and touch).This set of registers is referred to collectively as sensory memory.These registers are temporary storage places for sensory information until it can be attended to, recognized, and moved further along in the memory system.Sensory information that is not attended to is quickly forgotten.The information in each register that we attend to goes on to be recognized and enters the second stage of memory, short-term memory, which is comparable to our this encoding of sensory input from sensory memory into short-term memory. If attended to and studied, information in short-term memory will be encoded into long-term memory where it is stored for later use.If not attended to, the information will be forgotten. To use the information stored in long-term memory, we bring it back into short-term memory (a process called retrieval).If we cannot retrieve such information, it is said to be forgotten.Later in the chapter we will consider explanations for such forgetting.
7 The Three-Stage Model Sensory memory (SM) Consists of a set of five registers that serve as temporary storage places, one from each senseUsed for incoming sensory information from the physical environment until we attend to it, interpret it, and it proceeds to the next stage of memory
8 The Three-Stage Model Iconic memory Is an exact copy of visual informationLess than a second in durationHas very large capacityConsider the example of a cartoon movie, which is nothing more than a series of still drawings flashed in rapid succession.Iconic memory allows us to perceive motion in the drawings.
9 Temporal integration procedure Testing Iconic MemoryTemporal integration procedureInvolves giving two random meaningless dot patterns sequentially at the same visual location with a brief time delay between the two presentationsCreates a meaningful pattern when the two patterns are integrated somewhere in the memory systemTime delay between the two presentations must be no longer than one second or no meaningful pattern can be perceivedFor a meaningful pattern to be perceived, the two patterns must be integrated somewhere in the memory system.However, if the time delay between the two presentations is greater than one second, no meaningful pattern can be perceived because the image from the first pattern has faded from iconic memory.
10 An Example of the Temporal Integration Procedure In this experimental procedure, two meaningless patterns (such as a and b) are shown sequentially at the same visual location. If the time interval between the two patterns is less than a second, a meaningful pattern (in this example, the letters V O H) is seen. The meaningful pattern can only be perceived when the two other patterns are integrated, so this integration must be taking place within our memory system, in what we call the visual sensory register or iconicmemory. (From Eriksen & Collins, 1967.)What do you see?
11 Testing Iconic MemorySperling’s full- and partial-report proceduresParticipants presented with a different 3 x 3 matrix of unrelated consonants (a total of 9) for 50 ms across numerous experimental trialsFull-report procedureParticipants had to report the entire matrixParticipants sensed the entire matrix but could not report all 9 lettersPartial-report procedureParticipants had to report only one row of the matrixAn immediate auditory cue resulted in successful recall; a one second delay resulted in poorer recallIn the full-report procedure participants had to report the entire matrixParticipants said they sensed the entire matrix but that it had faded from memory before they could report all 9 lettersIn the partial-report procedure, the participants had to report only one row of the matrix, a row indicated by an auditory cue on each trialWhen the auditory cue was given immediately after the brief presentation of the letter matrix, participants recalled the indicated row 100% of the timeWhen there was a one second delay between presentation of the matrix and the auditory cue, participants’ recall of the cued row worsened
12 A Letter MatrixA letter matrix like those used in Sperling’s iconic memory researchOn each trial, a different letter matrix is shown for 50 milliseconds. In the full-report procedure, participants attempt to recall all of the letters in the matrix.In the partial-report procedure, participants get an auditory cue following the matrix that tells them which row to report—high-pitched tone, recall top row; medium-pitched tone, recall middle row; and low-pitched tone, recall bottom row.The row that is cued is varied randomly across trials, so the participant has no way of knowing which row will be cued on any particular trial. In addition, the time between the letter matrix presentation and the auditory cue is varied.
13 What does the lightning tell you? Three or four bolts of lightning overlap in our iconic memory, leading to the perception of one continuous bolt.It is iconic memory that allows us to see the world as continuous and not as a series of unconnected snapshots.
14 Short-term memory (STM) The Three-Stage ModelShort-term memory (STM)Is the memory stage in which the recognized information from sensory memory enters consciousnessInvolves present, conscious cognitive processingServes as a place to rehearse informationInvolves concentrating on information or it will be lost in 30 secondsServes as a place to rehearse information so it can be transferred to long-term memory and as a place to bring information from long-term memory when asked to recall it.The memory stage with a small capacity (7 6 2 chunks) and brief duration (30 seconds) that we are consciously aware of and in which we do our problem solving, reasoning, and decision making.
15 Capacity of Short-Term Memory Memory spanAverage number of items that can be remembered across a series of memory span trialsHumans have a memory span of 7+/- 2 (5 to 9) chunks of informationMemory span taskTests for the capacity of short-term memory by giving a series of items one at a time in a given orderChunkMeaningful unit of informationExperts in a given domain tend to have larger chunks for information in their area of expertise.
16 Duration of Short-Term Memory Distractor taskPeople given a small amount of information (e.g., three unrelated consonants such as CWZ)Immediate distraction used to deter concentration on the information for a brief time period (by counting backward aloud by 3’s)Information recall gatheredMaintenance rehearsal used to keep information in short-term memoryMaintenance rehearsal used to keep information in short-term memory (i.e., repeating information in short-term memory to keep in from fading from short-term memory)
17 Results for the Short-Term Memory Distractor Task This figure shows how forgetting in short-term memory occurs over time. As the length of the distractor interval increases, forgetting increases very rapidly. In less than 30 seconds, recall is essentially zero. (From Peterson & Peterson, 1959.)
19 Short-Term Memory Maintenance rehearsal Type of rehearsal in short-term memory in which the information is repeated over and over again in order to maintain it
20 Long-term memory (LTM) The Three-Stage ModelLong-term memory (LTM)Allows storage of information for a long period of time (perhaps permanently)Has essentially unlimited capacity
21 Types of Long-Term Memory Explicit memory (also called declarative memory)Long-term memory for factual knowledge and personal experiencesRequires conscious recallTwo types of explicit memoriesSemantic memoriesEpisodic memoriesSemantic memories are memories for factual knowledge that is true for everyone (e.g., the current President of the United States)Episodic memories are memories for personal life experiences (e.g., your senior prom night)
23 Types of Long-Term Memory Implicit memory (also called non-declarative memory)Long-term memory that influences behavior, but does not require conscious awareness or declarative statementsProcedural memoriesHave a physical procedural aspect to themPrimingInvolves implicit influence of an earlier presented stimulus on the response to a later stimulusImplicit memory (also called non-declarative memory)Is long-term memory that influences behavior, but does not require conscious awareness or declarative statements (e.g., for most adults, driving a car; walking)Conditioning memoriesBecome automatic responses to certain stimuli (e.g., feeling tense when police car lights are flashing behind us).For a tennis expert, such as Serena Williams, the movements to play the game are implicit, procedural memories, whereas for the average person, such movements require conscious recall, and are more semantic memories
24 Amnesia: Loss of Long-Term Memories AmnesicsPeople with severe memory deficits following brain surgery or injuryAnterograde amnesiaInability to form long-term memories for events following brain surgery or traumaRetrograde amnesiaInability to remember events before, especially just before, surgery or traumaH. M. had his hippocampus and surrounding temporal lobe area removed at age 27 (to reduce epileptic seizures).Before the operation, both his short- and long-term memories were normal.After the operation, he didn’t seem to be able to store any new information in long-term memory.H.M. suffered from anterograde amnesia – the inability to form long-term memories for events following brain surgery or trauma.By contrast, retrograde amnesia is the inability to remember events before, especially just before, the surgery or trauma.H. M.’s short-term memory did not suffer any substantial damage after the operation.
25 The Mirror-Tracing Task The task is to trace the outline of a star (or some other shape) with a metal stylus when the star and your hand can be seen only in the mirrorThus, the tracing movements have to be made in the direction opposite from the way in which they appear in the mirrorWhen the stylus moves off of the star outline (each red section in the illustrated tracing), it makes electrical contact with the underlying aluminum plate and a tracing error is recorded.There is non-conducting tape on the star outline so as long as the stylus stays on the outline, no electrical contact is made.Just like we would, H. M. improved from session to session (the number of errors he made decreased) as he gained more experience in this task.However, unlike us, he could not remember ever having performed the task before and had to have the task explained to him each session.As explained in the text, this means that he formed new implicit procedural memories for how to do the task, but he did not form new explicit episodic memories of having performed the task.
26 Infantile AmnesiaCerebellum seems to be important for formation of implicit memoriesHippocampus seems to be important for formation of explicit memoriesHippocampus does not fully develop until about the age of 3This explains why we cannot remember as adults events that occurred prior to this age
27 Evidence for the Short-Term vs. Long-Term Distinction Free recall taskExperimental procedure in which participants are given a list of words one at a time, then asked to recall them in any order they wishPrimacy effectRecency effect After viewing the next slide, what can you conclude about each of these effects?Compared with the middle of such lists, the recall of the items at the start of the list is superior (the primacy effect)Compared with the middle of such lists, the recall of the items at the end of the list is superior (the recency effect)
28 Evidence for the Short-Term vs. Long-Term Distinction Recency effect is caused by recall from short-term memoryPrimacy effect is the result of superior recall from long-term memory of the first few words in the listThe first few words enter an empty long-term memory and get proportionately more attention than the words in the middle of the list and can thus be transferred into long-term memory.The last few words are still in short-term memory at the time of recall.If recall is delayed by having participants count rapidly backward by 3’s for 30 seconds, the recency effect is eliminated, but the primacy effect remains.To eliminate the primacy effect, simply rehearse each of the items on the list equally.
29 Serial Position Effects for the Free Recall Task The superior recall of the first few items presented relative to those in the middle of the list is called the primacy effect.This effect is due to the fact that the primary items in the list are studied more and so have a higher probability of being in long-term memory for later recall.The recency effect refers to the superior recall of the last few items presented versus those in the middle of the list.This effect is due to the easy immediate recall of the items presently in short-term memory (those recently presented).
30 Encoding Information into Memory How We Encode InformationHow to Improve Encoding
31 Memory System Processes EncodingProcess of transferring information from one memory stage to the nextStorageProcess of maintaining information in a particular stageRetrievalProcess of bringing stored information from long-term memory to the conscious level in short-term memory
32 How We Encode Information Effortful processingOccurs consciously and requires attentionAutomatic processingOccurs subconsciously and does not require attentionFor a particular type of processing, much practice is needed.
33 How We Encode Information Levels-of-Processing TheoryDescribes what types of encoding lead to better retrievalContains three levels of processingPhysical: How the information appearsAcoustic: How the information soundsSemantic: What the information meansLong-term memory is best for information encoded semantically, next best for information encoded acoustically, and worst of information encoded physically.
34 Differences in Recognition Memory for Words Processed at Different Levels Participants were presented a long list of words one at a time and had to answer a question about each word as it was presentedWhat does the figure tell us about differences in recognition memory?The nature of the questions led to different levels of processing— physical (how it was printed), acoustic (how it sounded), or semantic (what it meant).The level of processing dramatically affected the participants’ later ability to recognize the word as one that had been on the list. (Adapted from Craik & Tulving, 1975; Experiment 2.)
35 How We Encode Information Elaborative rehearsalRehearsing information by relating new information to information already in long-term memoryProvides more retrieval cues to facilitate retrievalContrasts with maintenance rehearsal (i.e., the repetitive cycling of information in short-term memory)
36 How We Encode Information Self-reference effectContends it is easier to remember information that you have related to yourselfSuggests such connections provide more retrieval cues and lend more meaning to the new information
37 Environmental Effects on Encoding Encoding specificity principleProposes that cues present during encoding serve as the best cues for retrievalState-dependent memoryDepends upon the relationship of one’s physiological state at the time of encoding and at the time of retrievalThis is why the various concepts and examples that you relate to a new concept during elaborative rehearsal help you remember the concept.
38 Environmental Effects on Encoding Mood-dependent memory effectsDemonstrate that memory is better when a person’s mood is the same during encoding and retrievalMood-congruence effectDemonstrates that memory is better for experiences that are congruent with a person’s current moodMood-dependent memory effectsFor example, if you are happy during encoding information, it is easier to retrieve that information if you are happy at the time of retrievalMood-congruence effectFor example, when we are sad it is easier to retrieve negative events in our lives
39 How to Improve Encoding MnemonicsMemory aids that require elaborative rehearsalMethod of lociSequential pieces of information to be remembered are first associated with sequential locations in a very familiar room or locationPeg-word systemItems to be remembered that are visually associated in a memorized jingleWhen retrieving the information, you merely mentally go around the room (or location) and retrieve the item stored at each sequential location; uses elaborative mental imagery.
40 Other Tips for Improving Encoding Spacing effect (or distributed study effect)Contends that memory will improve if you study for an exam over an extended time interval rather than just a few days before the examOverlearningInvolves studying material past the point of initial learningHas been demonstrated to aid in retrieval of that information
41 Retrieving Information from Memory How to Measure RetrievalWhy We ForgetThe Reconstructive Nature of Retrieval
42 How to Measure Retrieval RecallMeasure of retrieval that requires the reproduction of the information with essentially no retrieval cuesRecognitionMeasure of retrieval that only requires the identification of the information in the presence of retrieval cuesRelearning (savings method)Measure of the amount of time saved when learning information for a second time
43 An Early Study Ebbinghaus Hermann Ebbinghaus Conducted first experimental studies on human memory more than 100 years ago using the relearning methodMastered and relearned list of nonsense syllablesComputed a savings scoreConcluded that the “forgetting curve” reveals that most forgetting occurs in the first two days after learning materialHe would study a list of nonsense syllables until he could correctly recite the complete list without any hesitations. He then put the list aside and waited some period of time and then relearned the list to the same criterion.To get a measure of learning, he computed a savings score – the reduction in the number of trials it took him to reach criterion.Result? The “forgetting curve” reveals that most forgetting occurs in the first two days after learning material.Bettmann/CorbisHermann Ebbinghaus
44 Forgetting Curve for Long-Term Memory The course of long-term forgetting usually takes on the shape of this figure—a rapid steep decrease that then levels off. In Ebbinghaus’s memory research with nonsense syllables, the amount of time he saved relearning the material decreased dramatically for the first 2 days following initial learning and then leveled off after that. (Adapted from Ebbinghaus, 1885/1964.)
45 Encoding failure theory Why We ForgetEncoding failure theoryContends sometimes forgetting is not really forgetting, but rather that the information never entered long-term memory in the first placeStorage decay theorySuggests that forgetting occurs because of a problem in the storage of the informationThe biological trace of the memory gradually decays over time and the periodic usage of the information will help to maintain it in storage
46 An Example of Encoding Failure The answer is likely encoding failure.Most of us are not that interested in coins and have never bothered to encode the exact features of a penny into long-term memory, so we have difficulty in choosing the real penny. This may be referred to as forgetting, but it is more appropriately called encoding failure. You can’t really forget something that you did not put into long-term memory. The first penny (a) is the real penny. (From Nickerson & Adams, 1979.)Can you identify the real penny?Most Americans cannot. Why?
47 Why We Forget Cue-dependent theory Interference theory Posits that people forget because the cues necessary for retrieval are not availableSuggests information is in memory, but inaccessibleInterference theoryProposes that other similar information interferes and makes the forgotten information inaccessibleCue dependent theory is analogous to knowing a book is in the library but you cannot access it because the library lacks call numbers.
48 Types of Interference Proactive interference Retroactive interference Occurs when information you already know makes it hard to retrieve newly learned informationRetroactive interferenceOccurs when information you just learned makes it hard to retrieve old informationLet’s consider an example of each kind of interference.Think about changing phone numbers after having a certain number for many years. When asked for your new phone number, remembering the old one interferes with retrieving the new one.This is proactive interferenceNow think about being at a party with many people you don’t know. You meet someone whom you want to talk to later, but after meeting her, you are introduced to many more people. Now, you cannot remember her name.This is retroactive interference
49 Types of InterferenceIn the proactive interference example, prior learning (French) disrupts memory for newly learned information (Spanish)In the retroactive interference example, new learning (Spanish) disrupts memory for information learned earlier (French).
51 The Reconstructive Nature of Retrieval Retrieval re-constructionIs guided by schemasSchemasAre organized frameworks of knowledge about people, objects, and events that tell us what normally happens in a given situationAllow more efficient information encoding and retrievingCan lead people to “misremember” information so that it is more consistent with personal schemasWhen reading a newspaper article, for instance, we usually code the gist or main theme of the story, along with some of the story’s highlights.Then, when we retrieve the information from our memory, we re-construct a memory of the story using the theme and highlights.
52 The Reconstructive Nature of Retrieval Source misattributionOccurs when we do not remember the true source of a memory and attribute the memory to the wrong sourceResults in false memories, which are inaccurate memories that feel as real as accurate memoriesFalse memoriesCan also occur because of the misinformation effect, which occurs when a memory is distorted by subsequent exposure to misleading information
53 A Study of False Memories Loftus and Palmer (1974) showed people a film of a traffic accident and later tested their memory for the accidentSome people were asked “How fast were the cars going when they smashed into each other?”Others were asked “How fast were the cars going when they hit each other?” Can you predict the responses for each group? What contributed to your answer?Participants asked the first question estimated a higher speed at impact and reported seeing broken glass when there was none.
54 Memory and Testimony False memories Suggest that eyewitness testimony is subject to error and manipulated by misleading informationSuggest that recovered memories are not necessarily accurate