Unit 1: Understanding the individual Memory

Unit 1: Understanding the individualMemory • Week one: Introduction to memory • Week two: Models of memory • Week three: Forgetting and Mnemonics

Activity: What is Memory? • Write down a list of everything that you did yesterday. Try to recall every single activity that you did. • Write down a list of everything you did on the 5th of December last year. Try to recall as much as you can. • What do you notice about what you can remember for each date? • What is the role that memory plays in each of these activities? For example, think about the different types of information that you need • What can you do that doesn’t require memory?

What is Memory • Memory is a cognitive process used to encode, store, and retrieve information. • Encoding - means to put something into a code, in this case the code used to store information in the memory. Encoding takes many forms: visual, auditory, taste, smell etc • Storage -as a result of encoding, the information is stored within the memory system. • Retrieval -the recovery of stored information from the memory system. It includes recognition, recall and reconstruction.

What is Memory • Several theories of memory are based on the assumption that there are 3 kinds of memory: • Sensory memory; this is a storage system that holds information in a relatively unprocessed form for fractions of a second after the physical stimulus is no longer available. • Baddeley (1988) suggested that one function of this kind of storage is to allow information from successive eye-fixations to last for a long enough time to be integrated and so to give continuity to an individual’s visual environment e.g. Like a film

What is Memory • Short-term memory • a temporary place for storing information during which it receives limited processing. • Short-term memory has a very limited capacity and short duration, unless the information in it is maintained through rehearsal. • Long-term memory • this is a relatively permanent store which has unlimited capacity and duration.

What is Memory • Different kinds of long-term memory have been identified: • episodic (memory for personal events) • semantic (memory for facts and information) • procedural (memory for actions and skills).

Short-term Memory • Some researchers (eg Atkinson and Shiffrin, 1968) see short term memory simply as a temporary storage depot for incoming signals from the senses. Others (eg Baddeley 1986) prefer to use the term ‘working memory’ to indicate its dynamic and flexible aspects. • Encoding • Information arrives in sensory memory in its original form (or ‘modality’), eg acoustic, visual, etc. However, as memory processes are unconscious individuals are not aware of which type of encoding they use. • Substitution error studies have provided much of the information about coding, eg Conrad (1964).

Short-term Memory • Conrad (1964) • Aim: to find out whether people used acoustic coding in short-term memory, even when information was presented visually. • Procedure: Participants were shown a random sequence of 6 consonants projected in rapid succession onto a screen. (The strings of consonants were either acoustically similar or acoustically dissimilar.) • Participants were asked to write down the letters in the same order as they appeared. • Letters were presented too fast for the participants to keep up, so they had to rely on memory. • Conrad noted the errors made by the participants.

Short-term Memory • Findings: • The majority of the errors involved the substitution of a similar sounding letter • Participants found that it was more difficult to recall strings of acoustically similar letters in the correct order than dissimilar letters, even though they were presented visually. • Conclusions: • The visually presented information must have been encoded acoustically. • The short term memory is primarily encoded on the basis of sound.

Short-term Memory • Baddeley (1986) found that words with similar sounds were much harder to recall than words, which did not sound alike. Similarity of meaning had only a slight detrimental effect on performance. Baddeley, like Conrad, concluded that short-term memory relies more on the sound of words than on their meaning. • Other researchers (eg Brandimonte et al 1992) have found that although acoustic coding is the preferred method of encoding in short-term memory, other modes of representation are also possible. For example in the absence of acoustic coding, visual coding may be substituted.

STM capacity experiment • You will now be shown a series of numbers in lists. After each list has finished, please try to write down the numbers you have just seen in order.

Short-term Memory • Capacity • Jacobs (1887) conducted the first systematic study of the capacity of short-term memory by devising a technique called the ‘memory span’. He found that the memory span for digits or letters was between 5 and 9 items and that short-term memory span increased with age (either due to increased brain capacity or memory techniques).

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Short-term Memory • ‘Most people have a digit span of seven, plus or minus two’ Miller (1956) • This has been called Miller’s magic number 7. Miller claimed that this finding holds good for lists of digits, letters, words or larger ‘chunks’ of information. • Miller reported that the key issue is ‘chunks’ (integrated pieces or units of information). About 7 ‘chunks’ of information can be held in the short-term memory at any one time. The question of what constitutes ‘chunks’ depends on personal experience. • ‘Chunking’ improves the capacity of memory but it may reduce its accuracy

Multi-store model • This model arose from the information processing approach where memory is characterised as a flow of information through a system. • The system is divided into a set of stages and information passes through each stage in a fixed sequence. • The Multi-store model suggests that incoming data passes through a sensory store where it can be registered for very brief periods of time before decaying or being passed into a short-term memory store. • There are two types of sensory storage: • Iconic storage – the store associated with visual information • Echoic storage – the store associated with auditory information • Atkinson and Shiffrin believed that memory traces in the short-term memory are fragile and can be lost within 30 seconds unless they are rehearsed.

Short-term Memory • Difficult to assess capacity of short-term memory: two main ways are span measures and recency effects in free recall. • Span measures e.g. digit span (Jacobs, 1887) require the participant to repeat back immediately a list of random digits in the correct order. • Span of immediate memory generally seven, plus or minus two, whether the units are numbers, letters or words. • Miller (1956) proposed that the capacity of short term memory depends more on the number of chunks rather than individual units.

Recency Effects Experiment • In this serial position experiment, you will hear a list of words. At the end of the list, you must write down the words you heard in any order you like. • The task will then be repeated, but before recalling, you must count backwards in 3s from 100.

Short-term Memory • Primacy and recency effects measured in studies of free recall, participants recall words from a list in any order immediately after it has been presented. • Recency effect= last few items in a list are usually better remembered than items in the middle. • Primacy effect=first few items in a list are usually better remembered than items in the middle. • Why?

Short-term Memory • Recency effect: based on information in the short-term store- suggests capacity is about 2 or 3 items. • Effect eliminated when interference task introduced between end of presentation and start of recall (Glanzer and Cunitz, 1966) • Primacy effect: depends mainly on extra rehearsal, items no longer in short-term store? • TASK: Read and summarise Glanzer and Cunitz’ experiment.

Short-term Memory Duration • Peterson and Peterson (1959) • Aim: To test how long short-term memory lasts when rehearsal is prevented. • Procedure: • Participants were briefly shown a consonant trigram (i.e. 3 letters such as MWG or CGX). • Participants were asked to count backwards in 3s from a specified number to stop them thinking about the letters. • After intervals of 3,6,9,12,15 or 18 seconds, participants were asked to recall the original trigram. • The procedure was repeated several times using different trigrams.

Short-term Memory Duration Findings: • Participants were able to recall 80% of trigrams after a 3 second interval. • Progressively fewer trigrams were recalled as the time intervals lengthened. • After 18 seconds, fewer than 10% of the trigrams were recalled correctly. • Conclusions: • If rehearsal is prevented, information vanishes rapidly from short-term memory. • Therefore, decay is the mechanism for forgetting in short-term memory.

Short-term Memory • The key point about findings based on the Brown-Peterson technique is that items disappear from short-term memory only when rehearsal is prevented. New items can only take their place if existing items move on. • Repetition serves as a method of continually reinserting the information into the short-term memory and thereby strengthening the memory. • Without rehearsal, the duration of short-term memory is less than 30 seconds.

Short-term Memory • Rehearsal • There are different types of rehearsal. Craik and Watkins (1973) distinguished between maintenance rehearsal, where, for example, a word is repeated out loud a number of times to keep it in short-term memory, and • elaborative rehearsal, in which information is processed in terms of its meaning. They suggested that maintenance rehearsal may be enough to keep information in short-term memory, while elaborative rehearsal is the type necessary to transfer information from short-term memory to long-term memory.

Evaluation of Multi-store model • 3 different kinds of memory stores- model based on evidence that there are important differences among the stores: • Temporal duration (e.g. STM- 18seconds (Peterson and Peterson,) • Storage capacity (e.g. Miller (1956) 7+/-2 chunks of information) • Forgetting mechanism (e.g. STM-primacy/recency effects, different types of rehearsal) • Effects of brain damage (e.g. amnesic patients have poor long-term memory but almost normal short-term memory, Baddeley and Warrington, 1970)

Evaluation of Multi-store model • Problems and limitations · Rehearsal does not always lead to storage. · If coding in the short-term memory is mainly acoustic, how do we understand language? · How does the model explain flashbulb memories? · Some types of information are not amenable to rehearsal, e.g. smells and yet we remember them. Memory oversimplified in this model?

Working Memory • Baddeley and Hitch (1974): argued that concept of STM should be replaced with WM. WM consists of 3 components: • Central executive: responsible for the supervision of information integration and for coordinating the slave systems. It is also responsible for directing attention to relevant information • Articulatory or phonological loop: holds information briefly in a phonological or speech-based form. Prevents decay by continuously articulating its contents. • Visuo-spatial sketch pad: stores visual and spatial information. It can be used, for example, for constructing and manipulating visual images, and for the representation of mental maps.

Working Memory • Baddeley, Thomson and Buchanan (1975) studied the articulatory loop. • Asked participants to recall sets of 5 words in the correct order. Word-length effect: better with short words than long words. Indicates limited capacity of articulatory loop. • Hitch and Baddeley (1976): tested two predictions of the working memory model: • If two tasks make use of the same component, they cannot be performed successfully together. • If two tasks make use of different components, it should be possible to perform them as well together as separately.

Working Memory • Participants carried out verbal reasoning task-involved deciding whether a set of sentences provided a true or false description of the letter pair that followed it (e.g. B is followed by A: AB). • Assumed that this task makes use of the central executive.

Working Memory • At the same time as carrying out the verbal reasoning task, participants were given an additional task (one of four conditions) before each trial: • ‘the’ repeatedly • ‘one, two, three, four, five’ • a different random string of digits out loud every trial • or there was no additional task (control).

It was assumed that the first two conditions would make use of the articulatory loop only because little thought or attention is involved. • In contrast, saying six random digits involves the central executive as well as the articulatory loop. • Predicted that only condition 3 should interfere with performance on the verbal reasoning task. • Results: reasoning performance slowed down only when the additional task was condition 3.

Working Memory Evaluation: • Working memory model concerned with both active processing and brief storage of information. • Multi-store model minimises active involvement of the individual in learning and remembering. • Therefore, working memory model relevant to everyday tasks such as mental arithmetic, verbal reasoning and comprehension. • Working memory model views verbal rehearsal as an optional process (one of two specialised systems) rather than the main process for retention of information. • Yet, little known about central executive, visuo-spatial sketch pad and the interaction between these components.

Long-term Memory • Multi-store model proposed by Atkinson and Shiffrin (1968) suggested that there is a single long-term memory store. • Critics have argued that this model is over-simplified and that it is improbable that all the knowledge we possess is stored in exactly the same form in one store. • Much research has been carried out to determine the number and nature of long-term memory stores

Long-term Memory • Episodic and semantic memory • Tulving (1972) argued for a distinction between episodic and semantic memory • Episodic memory: autobiographical- refers to storage of specific events or episodes. E.g. party you attended last weekend. • Semantic memory: general knowledge about the world e.g. facts and figures, language, etc.

Long-term Memory • Tulving (1972, p.386) defined semantic memory as: • ‘a mental thesaurus, organised knowledge a person possesses about words and other verbal symbols, their meanings and referents, about relations among them, and about rules, formulas, and algorithms for the manipulation of these symbols, concepts and relations • Distinction between semantic and episodic memory can be described in the following way: • Episodic: Wedding- remember who you went with, what various people wore, meal and party afterwards • Semantic: Knowledge of wedding ceremonies- e.g. usually in Church, sometimes registrar, legal ceremony which results in marriage, traditional wear for female is.., etc etc

Long-term Memory • Tulving (1989) carried out a study to investigate the distinction between episodic and semantic memory • A small dose of radioactive gold was injected into the bloodstream of participants (including Tulving). • Participants instructed to think about personal events OR general knowledge (e.g. history of psychology) • Blood flow in different areas of the brain recorded

Long-term Memory • Tulving (1989) Results: • Episodic memory associated with a high level of activation in the frontal cortex • Semantic memory associated with a high level of activation in the posterior or back regions of the cortex • Evidence supports Tulving’s view that there are separate long-term memory systems • Evaluation: difference in content of memories yet less clear that there is a difference in the processes involved. E.g. both rely heavily on each other

Long-term Memory Explicit and Implicit memory • Memory tests involve the use of direct instructions to participants to retrieve specific information (e.g. free recall, cued recall, recognition) • These tests are tests of explicit memory which, according to Graf and Schachter (1985) can be contrasted with implicit memory • Explicit memory ‘is revealed when performance on a task requires conscious recollection of previous experiences’ • Implicit memory ‘is revealed when performance on a task is facilitated in the absence of conscious recollection’

Long-term Memory • Explicit memory based on conscious recollection • Implicit memory not based on conscious recollection • How does one measure ‘implicit memory’? • Why is this distinction important?

Long-term Memory • Distinction useful when studying patients suffering from amnesia (partial loss of long-term memory usually caused by brain damage) • Patients have severe problems with long-term memory- yet mainly with explicit rather than implicit memory • Claparede (1911) hid a pin in his hand before shaking hands with an amnesic patient. • After this, the patient was reluctant to shake hands but was embarrassed as she could not explain this reluctance • Behaviour indicated implicit memory- this occurred in the absence of explicit memory of the accident

Long-term Memory • Graf, Squire and Mandler (1984) tested memory in amnesic patients (and controls) for list words in four ways: • 3 standard explicit memory tests (cued recall, free recall, recognition) • 1 implicit memory test: word completion task • Participants given three-letter word fragments (e.g. STR----) and asked to write down the first word they can think of beginning with these letters • Implicit memory measured by extent to which the word completions match words from a previous list • Results: found that amnesic patients performed worse than controls on the explicit memory tasks. Yet performed as well as controls on the implicit memory test

Long-term Memory Declarative and procedural knowledge systems • Cohen and Squire (1980) argued for a distinction between two long-term memory stores containing different types of knowledge: • Declarative knowledge: ‘knowing that’ e.g. what you had for lunch yesterday and capital of France. • Procedural knowledge: ‘knowing how’ e.g. how to ride a bicycle, swim, drive a car. • Explicit memory depends on declarative knowledge • Implicit memory depends on the procedural knowledge system

Long-term Memory Declarative and procedural knowledge systems • Cohen and Squire (1980) argue that amnesic patients have severe impairment of the declarative memory system and therefore find it hard to acquire new episodic and semantic memories. • Yet amnesic patients find it relatively easy to acquire new skills which rely on procedural memory e.g. dress-making, jigsaw completions, (Eysenck and Keane, 1995)

Long-term Memory Declarative and procedural knowledge systems • Squire, Knowlton and Musen (1993) argued that the main brain structures underlying declarative or explicit memory are located in the hippocampus, medial temporal lobes and the diencephalons. • Study by Squire et al (1992) supported this view. Using PET scans, found that blood flow in the right hippocampus was much higher when participants were performing a cued recall task compared to a word-completion task.

Long-term Memory Summary: Semantic and Episodic Explicit and Implicit Procedural and declarative

Forgetting The term forgetting has several meanings: · The information was never stored – problem of availability · The information was stored, but is difficult to retrieve – problem of accessibility (tip-of-the-tongue) · Confusion – problem of interference · Absentmindedness – problem of habit, attention, and automatic responses. Generally, forgetting is the inability to recall or recognise material which was previously stored in memory.

Forgetting Trace Decay • According to the decay theory, information is forgotten because of the passage of time. • Theoretical assumption that forgetting depends on the length of the retention interval rather than on events occurring during that interval. • Peterson and Peterson, (1959) found that memories were held in short-term memory for approximately 18 seconds, after which they disappeared via trace decay. • Hebb (1949) believed that, as a result of excitation of the nerve cells, a brief memory trace is laid down. At this stage the trace is very fragile and likely to be disrupted. With repeated neural activity (via rehearsal), a permanent structural change occurs and the memory is transferred to the long-term memory where it is no longer likely to decay.

Forgetting Displacement Displacement refers to the limited number of slots in short-term memory (7+/-2). When more items are introduced into short-term memory than there are slots, some of the old information must be knocked out of its slot, or ‘displaced’. Evidence for this comes from the Brown-Peterson technique, where the last few words on a list are displaced from short-term memory by the counting task.

Forgetting Interference • The idea behind this theory is that memories may be interfered with either by what has been learned before, or by what may be learned in the future. Forgetting increases with time because of interference from competing memories that have been acquired over time. • Proactive interference: when previous learning interferes with later learning and retention • Retroactive interference: when later learning disrupts memory for earlier learning

Forgetting • Interference was widely studied in the 1960s, but has attracted less attention since then. • Studies typically made use of the technique of paired-associates in which a word is associated with one word on a list and with a completely different word on another list. • Participants are required to learn one list and then the other. When given the stimulus word from the first list, it was found that participants frequently suffered from retroactive interference, in other words, they recalled the paired associate from the second list. • In both cases of interference, the greater the similarity of the interfering material, the greater the interference (Underwood and Postman, 1960).

Forgetting • Interference theory: Evaluation • Prediction: learning a second response to a given stimulus causes the first response to be unlearned. • Only occurs under laboratory conditions? • Slamecka (1966) asked participants to produce free associates to various stimulus words. • These stimulus words were then paired with new responses. • When participants asked to recall their free associates, no sign of retroactive intereference.

Unit 1: Understanding the individual Memory