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.

Three-Stage Model of Memory In This Chapter Three-Stage Model of Memory Encoding Information into Memory Retrieving Information from Memory

The Three-Stage Model of Memory Sensory Memory Short-Term Memory Long-Term Memory

The Three-Stage Model of Memory

The Three-Stage Model The Three-Stage Model Has guided research in memory since the late 1960s Views memory as composed of three relatively distinct stages Information 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.

The Three-Stage Model Sensory memory (SM) Consists of a set of five registers that serve as temporary storage places, one from each sense Used for incoming sensory information from the physical environment until we attend to it, interpret it, and it proceeds to the next stage of memory

The Three-Stage Model Iconic memory Is an exact copy of visual information Less than a second in duration Has very large capacity Consider 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.

Temporal integration procedure Testing Iconic Memory Temporal integration procedure Involves giving two random meaningless dot patterns sequentially at the same visual location with a brief time delay between the two presentations Creates a meaningful pattern when the two patterns are integrated somewhere in the memory system Time delay between the two presentations must be no longer than one second or no meaningful pattern can be perceived For 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.

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 iconic memory. (From Eriksen & Collins, 1967.) What do you see?

Testing Iconic Memory Sperling’s full- and partial-report procedures Participants presented with a different 3 x 3 matrix of unrelated consonants (a total of 9) for 50 ms across numerous experimental trials Full-report procedure Participants had to report the entire matrix Participants sensed the entire matrix but could not report all 9 letters Partial-report procedure Participants had to report only one row of the matrix An immediate auditory cue resulted in successful recall; a one second delay resulted in poorer recall In the full-report procedure participants had to report the entire matrix Participants said they sensed the entire matrix but that it had faded from memory before they could report all 9 letters In the partial-report procedure, the participants had to report only one row of the matrix, a row indicated by an auditory cue on each trial When the auditory cue was given immediately after the brief presentation of the letter matrix, participants recalled the indicated row 100% of the time When there was a one second delay between presentation of the matrix and the auditory cue, participants’ recall of the cued row worsened

A 3 3 3 Letter Matrix A 3 3 3 letter matrix like those used in Sperling’s iconic memory research On 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.

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.

Short-term memory (STM) The Three-Stage Model Short-term memory (STM) Is the memory stage in which the recognized information from sensory memory enters consciousness Involves present, conscious cognitive processing Serves as a place to rehearse information Involves concentrating on information or it will be lost in 30 seconds Serves 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.

Capacity of Short-Term Memory Memory span Average number of items that can be remembered across a series of memory span trials Humans have a memory span of 7+/- 2 (5 to 9) chunks of information Memory span task Tests for the capacity of short-term memory by giving a series of items one at a time in a given order Chunk Meaningful unit of information Experts in a given domain tend to have larger chunks for information in their area of expertise.

Duration of Short-Term Memory Distractor task People 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 gathered Maintenance rehearsal used to keep information in short-term memory Maintenance 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)

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.)

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

Long-term memory (LTM) The Three-Stage Model Long-term memory (LTM) Allows storage of information for a long period of time (perhaps permanently) Has essentially unlimited capacity

Types of Long-Term Memory Explicit memory (also called declarative memory) Long-term memory for factual knowledge and personal experiences Requires conscious recall Two types of explicit memories Semantic memories Episodic memories Semantic 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)

Types of Long-Term Memory

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 statements Procedural memories Have a physical procedural aspect to them Priming Involves implicit influence of an earlier presented stimulus on the response to a later stimulus Implicit 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 memories Become 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

Amnesia: Loss of Long-Term Memories Amnesics People with severe memory deficits following brain surgery or injury Anterograde amnesia Inability to form long-term memories for events following brain surgery or trauma Retrograde amnesia Inability to remember events before, especially just before, surgery or trauma H. 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.

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 mirror Thus, the tracing movements have to be made in the direction opposite from the way in which they appear in the mirror When 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.

Infantile Amnesia Cerebellum seems to be important for formation of implicit memories Hippocampus seems to be important for formation of explicit memories Hippocampus does not fully develop until about the age of 3 This explains why we cannot remember as adults events that occurred prior to this age

Evidence for the Short-Term vs. Long-Term Distinction Free recall task Experimental procedure in which participants are given a list of words one at a time, then asked to recall them in any order they wish Primacy effect Recency 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)

Evidence for the Short-Term vs. Long-Term Distinction Recency effect is caused by recall from short-term memory Primacy effect is the result of superior recall from long-term memory of the first few words in the list The 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.

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).

Encoding Information into Memory How We Encode Information How to Improve Encoding

Memory System Processes Encoding Process of transferring information from one memory stage to the next Storage Process of maintaining information in a particular stage Retrieval Process of bringing stored information from long-term memory to the conscious level in short-term memory

How We Encode Information Effortful processing Occurs consciously and requires attention Automatic processing Occurs subconsciously and does not require attention For a particular type of processing, much practice is needed.

How We Encode Information Levels-of-Processing Theory Describes what types of encoding lead to better retrieval Contains three levels of processing Physical: How the information appears Acoustic: How the information sounds Semantic: What the information means Long-term memory is best for information encoded semantically, next best for information encoded acoustically, and worst of information encoded physically.

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 presented What 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.)

How We Encode Information Elaborative rehearsal Rehearsing information by relating new information to information already in long-term memory Provides more retrieval cues to facilitate retrieval Contrasts with maintenance rehearsal (i.e., the repetitive cycling of information in short-term memory)

How We Encode Information Self-reference effect Contends it is easier to remember information that you have related to yourself Suggests such connections provide more retrieval cues and lend more meaning to the new information

Environmental Effects on Encoding Encoding specificity principle Proposes that cues present during encoding serve as the best cues for retrieval State-dependent memory Depends upon the relationship of one’s physiological state at the time of encoding and at the time of retrieval This is why the various concepts and examples that you relate to a new concept during elaborative rehearsal help you remember the concept.

Environmental Effects on Encoding Mood-dependent memory effects Demonstrate that memory is better when a person’s mood is the same during encoding and retrieval Mood-congruence effect Demonstrates that memory is better for experiences that are congruent with a person’s current mood Mood-dependent memory effects For example, if you are happy during encoding information, it is easier to retrieve that information if you are happy at the time of retrieval Mood-congruence effect For example, when we are sad it is easier to retrieve negative events in our lives

How to Improve Encoding Mnemonics Memory aids that require elaborative rehearsal Method of loci Sequential pieces of information to be remembered are first associated with sequential locations in a very familiar room or location Peg-word system Items to be remembered that are visually associated in a memorized jingle When 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.

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 exam Overlearning Involves studying material past the point of initial learning Has been demonstrated to aid in retrieval of that information

Retrieving Information from Memory How to Measure Retrieval Why We Forget The Reconstructive Nature of Retrieval

How to Measure Retrieval Recall Measure of retrieval that requires the reproduction of the information with essentially no retrieval cues Recognition Measure of retrieval that only requires the identification of the information in the presence of retrieval cues Relearning (savings method) Measure of the amount of time saved when learning information for a second time

An Early Study Ebbinghaus Hermann Ebbinghaus Conducted first experimental studies on human memory more than 100 years ago using the relearning method Mastered and relearned list of nonsense syllables Computed a savings score Concluded that the “forgetting curve” reveals that most forgetting occurs in the first two days after learning material He 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/Corbis Hermann Ebbinghaus

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.)

Encoding failure theory Why We Forget Encoding failure theory Contends sometimes forgetting is not really forgetting, but rather that the information never entered long-term memory in the first place Storage decay theory Suggests that forgetting occurs because of a problem in the storage of the information The biological trace of the memory gradually decays over time and the periodic usage of the information will help to maintain it in storage

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?

Why We Forget Cue-dependent theory Interference theory Posits that people forget because the cues necessary for retrieval are not available Suggests information is in memory, but inaccessible Interference theory Proposes that other similar information interferes and makes the forgotten information inaccessible Cue dependent theory is analogous to knowing a book is in the library but you cannot access it because the library lacks call numbers.

Types of Interference Proactive interference Retroactive interference Occurs when information you already know makes it hard to retrieve newly learned information Retroactive interference Occurs when information you just learned makes it hard to retrieve old information Let’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 interference Now 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

Types of Interference In 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).

The Reconstructive Nature of Retrieval Retrieval re-construction Is guided by schemas Schemas Are organized frameworks of knowledge about people, objects, and events that tell us what normally happens in a given situation Allow more efficient information encoding and retrieving Can lead people to “misremember” information so that it is more consistent with personal schemas When 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.

The Reconstructive Nature of Retrieval Source misattribution Occurs when we do not remember the true source of a memory and attribute the memory to the wrong source Results in false memories, which are inaccurate memories that feel as real as accurate memories False memories Can also occur because of the misinformation effect, which occurs when a memory is distorted by subsequent exposure to misleading information

A Study of False Memories Loftus and Palmer (1974) showed people a film of a traffic accident and later tested their memory for the accident Some 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.

Memory and Testimony False memories Suggest that eyewitness testimony is subject to error and manipulated by misleading information Suggest that recovered memories are not necessarily accurate