1 Short-Term Memory 1 Short-Term Memory 46AC Cognition Short-Term Memory 2 Different Kinds of Remembering • Episodic Memory – Events that have happened in everyday life • Semantic Memory – Facts • Procedural Memory – Skills (e.g. remembering how to ride a bike) • Sensory Memory • Short Term Memory Short-Term Memory 3 Short-Term Memory “There seems to be a presence-chamber in my mind where full consciousness holds court, and where two or three ideas are at the same time in audience, and an ante-chamber full of more or less allied ideas, which is situated just beyond the full ken of consciousness. Out of this ante-chamber the ideas most nearly allied to those in the presence chamber appear to be summoned in a mechanically logical way” Francis Galton (1883) 2 Short-Term Memory 4 The Modal Model Atkinson & Shiffrin (1971) Short-Term Memory 5 Evidence for Separate Shortand Long-term Stores • Capacity • Serial position effect • Mechanisms of forgetting • Effects of brain damage Short-Term Memory 6 Capacity • STS has limited storage capacity – Digit span = “7 plus or minus 2” items – But span of items increased by “chunking” (Miller, 1956) • BAFDILTUN easier to remember than 464287598 • LTS has v. large capacity 3 Short-Term Memory 7 Serial Position (e.g., Postman & Phillips, 1965) • Free recall of word list • Participants tend to recall early items (primacy effect) and later items (recency effect) • Recency = items in STS • Primacy = items transferred to LTS Short-Term Memory 8 Short-Term Memory 9 Serial Position • Primacy and recency components open to separate sets of influences – Filled delay affects recency, not primacy (e.g., Glanzer & Cunitz, 1966; Postman & Phillips, 1965) – Familiarity of words, age etc. affect LTM, not recency • These portions are products of different mechanisms 4 Short-Term Memory 10 Different mechanisms of forgetting • STS = trace decay or interference (e.g., Peterson & Peterson, 1959) • LTS = interference but also cue-dependent forgetting: info is there but can’t be accessed (Tulving, 1974) Short-Term Memory 11 Short-Term Memory 12 Patient HM Milner (1966) • Surgical removal of tissue from temporal lobes and hippocampus • Able to recall info from earlier life but unable to acquire new info • No ability to consolidate new info into LTS = anterograde amnesia • Normal digit span ÍNormal STS, impaired LTS. 5 Short-Term Memory 13 Patient KF Shallice & Warrington (1970) • Damage to left parieto-occipital region • Good long term learning • Poor on STM tasks (digit span = 2-3 digits) • Normal primacy effect, reduced recency effect (just 1 item!) ÍShows the reverse dissociation: Impaired STS, normal LTS Short-Term Memory 14 Summary • Capacity: STS limited, LTS unlimited • Serial position effect: Primacy (LTS), recency (STS) • Different mechanisms of forgetting • Effects of brain damage: Double dissociation between STS and LTS Short-Term Memory 15 Problems for the Modal Model • Maintaining items in STS does not necessarily lead to transfer to LTS (Tulving, 1966) • Failure to learn from repeated incidental exposure (e.g., Nickerson & Adams, 1979) • Long-term recency effects (Baddeley & Hitch, 1977) 6 Short-Term Memory 16 Problems for the Modal Model • Patients with impaired STS capacity (e.g. KF) can have normal long term learning Short-Term Memory 17 Problems for the Modal Model • KF’s short-term forgetting of auditory letters and digits was much worse than forgetting of visual stimuli • Deficit seemed to be limited to verbal material (letters, words, digits) • Can’t argue that KF had impaired shortterm memory ÍMulti-component working memory Short-Term Memory 18 Separate visual and verbal stores? • Brooks (1968) • Subs visualised a block letter • Imagine each corner going in a clockwise direction • Respond “yes” if on outside, “no” if on inside (yes, yes, yes, no, no, yes….) • Respond vocally or by pointing 7 Short-Term Memory 19 Findings • Subs performed more poorly when pointing than when vocalising their response. • Visualising a block letter used resources also needed for reading and pointing • If have to do both get interference • But, visualising and responding vocally uses different resources so performance better Short-Term Memory 20 Complementary Task • Subs classified words in a phrase as nouns or not – “A bird in the hand is not in the bush” = “no, yes, no, no, yes, no, no, no, no, yes” • Obtained reverse result: – Subs better at pointing than responding vocally • Vocal response and pointing use different resources ÍSeparate visual and verbal components Short-Term Memory 21 Dual Task Experiments More problems for the modal model • Subs able to maintain a digit load whilst engaging in syntactic reasoning (Baddeley, 1986) • Primacy effect in free recall disrupted but not obliterated by concurrent 6 digit load. Recency not affected (Baddeley & Hitch, 1977) • Concurrent digit span has no effect on accuracy of retrieval from LTM (Baddeley et al., 1984) 8 Short-Term Memory 22 Dual Task Experiments • Digit load should leave little capacity for reasoning, learning, comprehending and retrieving • But, subs still able to do these • Abandon unitary model ÍOne system for storing digits, another for reasoning, long-term storage, another for visual/spatial material Short-Term Memory 23 Summary • Dual task experiments suggest there may be: – Separate systems for manipulating verbal and visual material – Separate systems for storing digits and reasoning, learning etc. Short-Term Memory 24 Working Memory Baddeley (1986, 1990) • Replaced the single STS with a multicomponent working memory • More emphasis on process rather than structure • Sought to understand the role of STS in a range of cognitive tasks (reasoning, learning, comprehending) 9 Short-Term Memory 25 Working Memory Baddeley (1986, 1990) • 3 Components: – Central executive • Limited capacity attentional controller • Deals with any cognitively demanding task – Phonological loop • Manipulation of speech-based info – Visuo-spatial sketchpad • Visual/spatial coding Short-Term Memory 26 Summary • Evidence suggested separate short-term and long-term storage mechanisms: modal memory (unitary STS) • But, dual task experiments argued against unitary STS • Working memory with separate verbal and visuo-spatial components 1 Language PSY9AC Cognition Overview • Structure of language • Language comprehension – Syntax – Sentence parsing: is it modular? The umpires talked to the players The umpires talked to the players The umpires talked to the players The umpire s talk ed to the play er s !i mpayr z t ck t tuw ! pley er s Sentence: Phrase: Word: Morpheme: Phoneme: e Discourse: Info giving: sports report Hierarchy of linguistic structure 2 Languages consist of symbols that represent objects or ideas. beach warm bright summer denotation connotations ‘SUN’ The relationship between the symbols and the objects/ideas is entirely arbitrary. SUN SON  DAUGHTER SON  Language symbols are discrete. Different symbols are used to express continuous differences. not: dog dog dog dog dog dog dog dog dog dog but: ‘small dog’ ‘big dog’ 3 man, bite, dog Man bites dog. Dog bites man. Man bites man. Dog bites dog. A limited amount of discrete symbols can be combined to create an unlimited number of messages. Grammar = a discrete combinatorial system Language is generative/productive • A person can, in principle, deal with 1020 sentences (100,000,000,000,000,000,000) • Need one hundred trillion years to memorise them all! Grammar is autonomous from meaning • Sentences can be “ungrammatical” yet meaningful: The child seems sleeping Who did a book about impress you • Others can be grammatical yet meaningless: ‘Twas brillig and the slithy toves Did gyre and gimble in the wabe (Lewis Carroll) Colourless green ideas sleep furiously (Noam Chomsky) 4 How language works • Brains contain: – lexicons of words and concepts they stand for – set of rules that combine words to convey relationships among concepts (syntax) Phrase structure • S ’ NP + VP The boy slept. • NP ’ (Det) + Adj* + N The little boy. • VP ’ V + NP The boy kicked the ball. • VP ’ V + S I watched the boy kick the ball. S NP VP V NP Det N Det NP The boy kicked the ball. Phrase structure 5 Syntactic ambiguity Yoko Ono will talk about her husband John Lennon who was killed in an interview with Barbara Walters. For sale: Mixing bowl set designed to please cook with round bottom for efficient beating. We will sell gasoline to anyone in a glass container. Tonight’s programme discusses, exercise, nutrition, and sex with Celtic forward Scott Wedman, Dr. Ruth Westheimer, and Dick Cavett. Pinker (1994) Syntactic ambiguity VP V NP PP discuss N sex with NP Dick Cavett VP V NP discuss N with PP sex P NP Dick Cavett P Tonight’s programme discusses sex with Dick Cavett. • Phrase structure conveys info about who did what to whom etc. The happy boy eats ice cream ‘Twas brillig and the slithy toves Did gyre and gimble in the wabe • Understanding the phrase structure helps make sense of the sentence • So how do you figure it out? 6 Sentence parsing • Wait for end of sentence and then figure out structure (assemble all possible structures?) or... • assign words to syntactic roles as you go along? the det NP N S VP dog likes V NP ice cream Garden path sentences Fat people eat accumulates. Since jay always jogs a mile seems like a short distance to him. The prime number few. The man who hunts ducks out on weekends. The horse raced past the barn fell. We seem to parse sentences as we go along Garden-path model Frazier & Rayner (1982) • Only one syntactical structure is initially constructed • Meaning is not involved in initial structure • The simplest structure is chosen using: – Minimal attachment – Late closure 7 Parsing strategies: minimal attachment • Attach any phrase so as to create as few nodes (branches) as possible. S NP VP V NP PP I saw the man with binoculars. S NP VP V NP NP PP I saw the man with binoculars. Parsing strategies: late closure • Attach any new words to the phrase that is currently being processed. • Consider: John said that Sarah will do the work yesterday • Late closure leads us to add “yesterday” to the VP about doing the work. 8 Syntax and semantics The defendant examined by the lawyer turned out to be unreliable. The evidence examined by the lawyer turned out to be unreliable. • Eye movement data suggest ambiguity for both sentences (Ferreira & Clifton, 1986) Readers use minimal attachment even when semantically implausible. spoken or written word recognition syntactic processing semantic processing pragmatic interpretation Garden-path model = modular theory Syntax and semantics (1) As the woman edited the magazine amused all the reporters. (2) As the woman sailed the magazine amused all the reporters. • Semantics favouring wrong structure greater in (1) than (2). • More regressions in (1) than (2); fixations in verb region (“amused”) longer in (1) than (2). Semantics are used in syntactic analysis. Pickering & Traxler (1998) 9 spoken or written word recognition syntactic processing semantic processing pragmatic interpretation Interactionist view All relevant sources of information are available to the parser • Semantics • Statistical properties – Assume most frequent role of word (e.g., “duck” and “train”) – Adjectives tend to be followed by nouns (fat people eat accumulates) • Previous context • Prosody Constraint-based theory (MacDonald et al, 1994) Unrestricted race model (Van Gompel et al, 2000) P: The grand jury thing has its, uh, uh, uh—view of this they might uh. Suppose we have a grand jury proceeding. Would that, would that, what would that do to the Ervin thing? Would it go right ahead anyway? D: Probably. P: But then on that score, though we have-let me just, uh, run by that, that—You do that on a grand jury, we could then have a much better cause in terms of saying, “Look this is a grand jury, in which, uh, the prosecutor—” How about a special prosecutor? We could use Peterson… 10 Pragmatics • Language in real use: Woman: “I’m leaving you” Man: “Who is he?” • Figurative language (metaphor, idiom) • Shared knowledge/beliefs between speaker and listener • Language comprehension is not a sequential bottom-up process. • Language comprehension is highly interactive. Summary 1 Face Recognition II 1 Computer modelling Charlie Frowd Face Recognition II 2 Real Neuron (Carlson, 1986; reprinted in Ellis & Humphreys, 1999) Face Recognition II 3 Artificial Neuron Input to neuron: Neti = _iWijAj If sum of inputs > threshold, unit is Activated and signal is propagated ‘neuron’/unit Weighted connections Dendrites Axon 2 Face Recognition II 4 Word recognition network (McClelland & Rumelhart, 1981) Face Recognition II 5 Simulation of memory retrieval (McClelland, 1981) Inhibitory Excitatory Face Recognition II 6 Jets & Sharks IAC - Interactive Activation & Competition Model Units – 68 units 27 gang members / 27 gang members’ names 14 properties Activation Varies between –0.20 and +1.00 Resting activation –0.10 Connection strengths +1 between person and properties -1 between units in mutually exclusive ‘clusters’ Location of the ‘memory’ 3 Face Recognition II 7 Burton, A.M., Bruce, V. & Johnston, R.A. (1990). Understanding face recognition with an interactive activation model. British Journal of Psychology, 81, 361-380. STRUCTURAL ENCODING FACE RECOGNITION UNITS PERSON IDENTITY NODES NAME GENERATION COGNITIVE SYSTEM EXPRESSION ANALYSIS FACIAL SPEECH ANALYSIS DIRECTED VISUAL PROCESSING Bruce & Young (1986) 9 Stored Descriptions of faces (Face Recognition Units) Person Identities Names Face Recognition Structural encoding Generate descriptions of the structure of the face seen Contain descriptions of different views for each known person (familiarity decisions) Specific PIN activated. Allows access to semantic information 4 Face Recognition II 10 Priming Bruce & Young (1986) Semantic priming. Facilitation through semantic associations Works within or between sensory modalities Familiarity decision to Stan Laurel’s face speeded by prior presentation of Oliver Hardy’s face etc. Short lived (decays) Repetition priming: long lasting Same stimuli repeated Within a sensory domain Both attributed to same mechanism in B&Y increased activation of FRUs 11 Stored Descriptions of faces (Face Recognition Units) Person Identity Nodes Names Face Recognition Structural encoding (Description of the face) Other routes to identity (e.g. Voice, name) Repetition and Semantic Priming Face Recognition II 12 The IAC Model PINs provide gateways to semantic information Occupation, interests, postal address, … Familiarity decisions made at PINs, B&Y – FRUs Names are now part of semantic information, B&Y – last separate stage 5 13 FACE RECOGNITION UNITS (FRU) PERSON IDENTITY NODES (PIN) NAME INPUT UNITS (NIU) SEMANTIC INFORMATION UNITS (SIU) FACE NAME Burton, Bruce & Johnston (1990) Reeves Mortimer Reeves Mortimer Comedian Reeves Mortimer Blair Blair Blair Politician The IAC Model FRUs SIUs NIUs PINs Tony Blair Reeves Mortimer Reeves Mortimer Comedian Reeves Mortimer Blair Blair Blair Politician Repetition Priming FRUs SIUs NIUs PINs Tony Blair 6 Reeves Mortimer Reeves Mortimer Comedian Reeves Mortimer Blair Blair Blair Politician Repetition Priming FRUs SIUs NIUs PINs Tony Blair Face Recognition II 17 Repetition Priming in IAC Caused by strengthening of FRU - PIN connections Reeves Mortimer Reeves Mortimer Comedian Reeves Mortimer Blair Blair Blair Politician Semantic Priming FRUs SIUs NIUs PINs Tony Blair 7 Reeves Mortimer Reeves Mortimer Comedian Reeves Mortimer Blair Blair Blair Politician Semantic Priming FRUs SIUs NIUs PINs Tony Blair Reeves Mortimer Reeves Mortimer Comedian Reeves Mortimer Blair Blair Blair Politician Semantic Priming FRUs SIUs NIUs PINs Tony Blair Face Recognition II 21 Semantic Priming in IAC Caused by back activation from SIUs to PINs Raised activation of PINs allows cross domain-priming 8 Face Recognition II 22 Computer simulation of UK and US political leaders Software on testing PCs Folder called ‘iac’ Instructions iac instucts.doc Simulation faces.bat Semantic priming (short-term) repetition priming Face Recognition II 23 FRU NIU PINs SIU Input Activation Face Recognition II 24 IAC Commands • Commands are at top of screen • input or i. Set name then level for a unit. Enter ‘1’ for input strength • cycle or cy. Runs simulator for a number of cycles. Default is 20 cycles. • set single 1. Sets cycle step to 1. • reset. Starts simulation again by returning units to resting state (-0.1V). Inputs remain. 1 46AC: Cognition Memory Processes. David I. Donaldson Memory involves multiple processes. Encoding Storage Retrieval Semantic Records Perceptual Records Binding Context Semantic Records Perceptual Records Re-instatement Context What factors influence remembering? Study Phase DOG TIME DOG TOP BLUE DROP Dog…dog… dog…dog... Test Phase TIME DOG HAND BLUE AIR SHIT OLD! LEVELS-OF-PROCESSING THEORY Craik & Lockheart (1972) Assumes that the attentional and perceptual processes operating at the time of learning determine what information is stored in LTM. Deeper levels of analysis produce more elaborate, longer lasting, and stronger memory traces than do shallow levels of analysis. 2 3 study tasks: (1) Structural e.g. Is the word in block capitals? (2) Acoustic e.g. Does the word rhyme with ‘cat’? (3) Semantic e.g. Does the word fit the sentence ‘the cat sat on the ___’. Craik & Tulving (1975) Depth of processing operates at encoding. Encoding Storage Retrieval Semantic Records Perceptual Records Binding Context Semantic Records Perceptual Records Re-instatement Context These findings suggest that the quality (rather than quantity) of processing is most important for memory. Hyde & Jenkins (1973) Compared intentional and incidental learning. 1) Rate the word on a ‘pleasantness’ scale. 2) Rate how frequent the word is in English. 3) Search the word for the letters ‘e’ and ‘g’. 4) Say which part of speech the word is from. 5) Say whether the word fits a given sentence. NB. No difference between incidental versus intentional learning Any data can be consistent with a ‘depth of processing’ account of memory processing. The theory is descriptive rather than predictive. Depth-of-processing is not the only factor that influences encoding. Elaboration and distinctiveness are also thought to be important….. 3 Craik & Tulving (1975) Manipulated elaboration at encoding. “She cooked the ______” Vs. “The bird flew down and carried off the struggling ______” At test, recall was twice as good for the words presented with complex sentences. FLASHBULB MEMORIES Vivid and detailed memory of a distinctive event. BUT People typically remember the ‘reception event’ rather than event itself. Debate exists as to whether flashbulb memories are really different from memories for other events. Brown & Kulik (1982) suggest that there is a special neural mechanism triggered by events that are emotional, surprising and highly important or ‘consequential’. McCloskey et al., (1988) investigated forgetting rates. However, no attempt was made to assess the emotional impact of the event. Neisser (1982) argues that the durability of ‘flashbulb’ memories results from little more than frequent rehearsal. 4 What other factors influence remembering? Remember, information needs to be available (i.e., encoded) and accessible (i.e., retrievable). What about effects at retrieval? Encoding Storage Retrieval Semantic Records Perceptual Records Binding Context Semantic Records Perceptual Records Re-instatement Context Different retrieval tasks produce different levels of memory performance. BUT The pattern of performance is complex. Recognition failure for recallable words. Both encoding and retrieval are important. Encoding Storage Retrieval Semantic Records Perceptual Records Binding Context Semantic Records Perceptual Records Re-instatement Context Memory is dependent on an interplay between the processing that occurs at encoding and retrieval. ENCODING SPECIFICITY THEORY Tulving & Thompson (1973) Assumes that the most effective ‘retrieval pathways’ are those that ‘re-instate’ processing that occurred when the to-be-remembered information was originally encoded. The degree of ‘overlap’ in the conditions at encoding and retrieval is critical for memory. CONTEXT EFFECTS Fisher and Craik (1976) Subjects studied a series of word-pairs, with two ‘associative encoding’ tasks, emphasising either meaning (‘CAT-DOG’) or sound (‘CAT-HAT’). Two ‘associative retrieval’ tasks: 1) Recall a studied word associated with ‘CAT’? 2) Recall a studied word sounding like ‘CAT’? 5 Fisher & Craik (1976) 0 5 10 15 20 25 30 35 40 45 50 MEANING SOUND Encoding Condition % Retrieved MEANING CUE SOUND CUE Encoding Condition Retrieval Condition INTERNAL CONTEXT EFFECTS Teasdale & Fogarty (1979) 0 10 20 30 40 50 60 70 80 90 SAD HAPPY Encoding Condition % Retrieved SAD HAPPY Encoding Condition Retrieval Condition 0 5 10 15 20 25 30 SOBER DRUNK Encoding Condition % Retrieved SOBER DRUNK INTERNAL CONTEXT EFFECTS Eich (1980) Encoding Condition Retrieval Condition EXTERNAL CONTEXT EFFECTS (Godden & Baddeley, 1975) 65 70 75 80 Dry Wet Recognition environment Dry learning environment Wet learning environment Different effects on recall and recognition EXTERNAL CONTEXT EFFECTS (Godden & Baddeley, 1975) Nothing is encoded or retrieved in isolation, information is always encoded within a ‘context’. 6 Multiple (interacting) factors contribute to memory performance. Levels-of-processing, elaboration and distinctiveness demonstrate the importance of the organisation of material and processing occurring at time of learning. Task differences, internal and external context effects demonstrate the importance of retrieval cues and the retrieval environment. The factors that influence remembering are not specific to any particular type of memory. The theory of ‘encoding specificity’ applies to episodic, semantic and procedural memory. Implications for studies of everyday memory and eyewitness memory. 46AC: Cognition Forgetting David I. Donaldson Can we remember everything? Remember - there are different types of memory. AUTOBIOGRAPHICAL MEMORY Defined as “memory for the events of one’s live” by Conway and Rubin (1993). Autobiographical memories include details about the particular place and time a particular event occurred (the spatio-temporal context). Debate exists as to whether autobiographical is dissociable from episodic memory…… What methods are typically used to investigate autobiographical memory? (1) WORD CUEING: recalling events in response to some sort of retrieval cue (e.g. Galton, 1883). (2) DIARY STUDIES: writing down information about personal events (e.g. Linton, 1975). WORD CUEING Galton (1883). Subject is presented with a cue word, and asked to recollect a personally experienced memory associated with that word. For example: ‘cake’, ‘dog’, ‘balloon’…. Typically the participant attempts to date the recalled incident - and rates it for various characteristics, e.g., vividness, detail, importance. BUT Word cueing is unconstrained and unverifiable. 1. A RETENTION FUNCTION An overall trend for increased forgetting over time - memory decay. 2. A REMINISCENCE BUMP Higher number of autobiographical memories for the 15 - 30 years old period. Explanations of the reminiscence bump: (1) The 15 to 30 years old period of live tends to be associated with the development of a stable adult self-concept. (2) Events occurring between 15 and 30 years of age are somehow more distinctive than events at other ages (Cohen & Faulker, 1988). BUT Reminiscence bump is also found for public events (Schuman & Rieger, 1992). Typically only found with older subjects. 3. INFANTILE AMNESIA An almost total absence of autobiographical memories from before the age of 5. Infantile Amnesia Memories for events between ages of 2 and 5 are relatively infrequent. Extremely unusual to remember events that took place before the age of 2. For the memories recalled, sensory & affective elements predominate. The memories tend to be isolated from temporal sequence of events. The memories tend to lack a clear sense of self. Explaining infantile amnesia: (1) Schactel (1947) - Organisation miss-match Prior to language a child’s conscious experience is organised in perceptual rather than conceptual schemas. Experience is represented in qualitatively different ways by adults and children (cf. encoding specificity theory). West (1999) found little difference between memories reported by older and younger subjects. OLD YOUNG Explaining infantile amnesia: (2) Freud (1948) - repression. Psychodynamic theory suggest that emotionally unpleasant or highly charged memories are repressed by the conscious mind into the unconscious. Lewis (1995) examined the repression account and suggested a reworking of psychodynamic theory to better account for infantile amnesia. Explaining infantile amnesia: (3) Nelson (1998) - memory system not formed. Young children are much better at describing the features of familiar repeated events than specific incidents. Brain development continues throughout early childhood - although some memory systems may be fully formed. What if we did remember everything? The Case of “S” (Luria, 1968) Hiroyuki Goto, 21, the current world record holder for the most digits of Pi memorised, required over nine hours to recite 42000+ digits [Seattle Times, 2-26-95]. S.’s, memory was not just good, it was astoundingly good. Luria employed very long strings of numbers, words, and nonsense syllables but could not detect any limit to S.’s ability to recall them (generally without mistake). S.'s memory was highly eidetic. He used this technique to memorise lists, and became a performing mnemonist. Luria discovered that S had some other unusual characteristics to his memory, including synesthesia. S was virtually paralysed when it came to understanding speech and metaphorical ideas, and he had an impaired ability to abstract general knowledge from his experiences. Forgetting is normal and desirable…….. How do we forget? MEMORY DECAY The forgetting curve. Ebbinghaus (1885) Ebbinghaus provides clear evidence that memory decays over time. BUT Repeatedly re-learning lists of nonsense syllables is not ecologically valid (especially regarding complexity and distortion). What methods are typically used to investigate autobiographical memory? (1) WORD CUEING: recalling events in response to some sort of retrieval cue (e.g. Galton, 1883). (2) DIARY STUDIES: writing down information about personal events (e.g. Linton , 1975). AUTOBIOGRAPHICAL MEMORY _ Defined as “memory for the events of one’s live” by Conway and Rubin (1993). Autobiographical memories include details about the particular place and time a particular event occurred (the spatio-temporal context). Debate exists as to whether autobiographical is dissociable from episodic memory…… DIARY STUDIES Linton (1982). Systematic 6 year study of her own memory, recording 2 events that occurred every day, rating the events for salience, emotionality and importance. Every month she re-read 2 of these descriptions - tried to remember the events described, including the date at which they occurred. The effect of repeated access on forgetting. Linton (1978). Linton failed to find any strong relationship between rated importance/emotionality and recall. But, initial ratings did not correspond to later ratings. “Characteristics of an event at time of encoding only affect memorability if the same qualities are present at time of recall”. Two types of forgetting - depending on the type of memory. Number of repetitions (1 - 12) Strength of memory Evidence suggests two influences on forgetting: 1) Decay - the memory trace is no longer available due to the time since encoding. 2) Interference - the memory trace is no longer accessible due to activity since encoding. Hypothetical effects of interference and decay. Forgetting tri-grams. Keppel & Underwood (1962). Interference can operate both forwards and backwards in time. Proactive Interference Experimental Group Control Group Learn List A ----- Learn List B Learn List B Control group has better memory for list B. Build-up of proactive interference over time Retroactive Interference Experimental Group Control Group Learn List A Learn List A Learn List B ----- Control group has better memory for list A. Build-up of retroactive interference GROUP Experimental Control TRIAL 1 378 LFP Build-up of proactive interference over time TRIAL 2 042 KTC TRIAL 3 739 XPZ TRIAL 4 JWT JWT Wickens et al. (1963). Release from proactive interference. Forgetting is both normal and desirable. Forgetting results from both decay and interference. To be remembered, information must be available and accessible. 1 Language and thought PSY9AC • Language = thought. Thought is just silent, subvocal speech (Watson, 1925). • Language ! thought. Language and thought are independent faculties (Chomsky, 1959). • Language and thought are related (Vygotsky, 1934). • Language affects thought. (Sapir- Whorf). The Sapir-Whorf Hypothesis (Benjamin Lee Whorf, Edward Sapir) • Linguistic determinism. Language determines the way we think. • Linguistic relativity. Different languages cause differences in thoughts of speakers 2 The Sapir-Whorf Hypothesis • Strong version: – Language determines thought • Weak: – Language affects perception • Weakest: – Language differences affect processing on tasks where linguistic encoding is important Evidence: Anthropological anecdotes English: “It is a dripping spring” Apache: “As water, or springs, whiteness moves downwards” “How utterly unlike our way of thinking” (Whorf) • Apaches speak differently so they think differently • Circular reasoning “I am indeed a friend of the German languageand not only now, but from long since–yes, before 20 years already…I would only some changes effect. I would only the language method–the luxurious, elaborate construction compress, the eternal parenthesis suppress, do away with annihilate; the introduction of more than 13 subjects in one sentence forbid; the verb so far to the front pull that one it without a telescope discover can.” Mark Twain (from Pinker, 1994) 3 Evidence: Some myths. “The Eskimo have XXX words for snow.” “The Hopi have one word for birds, and one word for all other flying objects (airplane, clouds dragonfly, pilot etc.)” “The Hopi have no lexical items describing units of time, or past, present, and future.” Colour terms If no verbal labels distinguishing between two colours, can speakers of this language • perceive the differences between these colours, • memorise these colours, • recognise these colours, equally well as speakers of a language that has labels for these colours? Berlin & Kay (1969) • There are only 11 basic colour terms (black, white, red, yellow, blue, green, brown, purple, pink, orange, grey). • There is an evolutionary determined hierarchy of colour labelling. • There is universal agreement as to what the best representative for each colour term is (focal colours). 4 yellow orange black red blue brown purple white green pink grey Rosch Heider (1972) • Research on the Dani (Papua-New Guinea) • Dani have only two colour words: mola (white) and mili (black) • Comparison of colour recognition and memory between American and Dani speakers. Munsell arbitrarily divided the hue circle into 100 steps, of equal visual change in hue, with the zero point at the beginning of the red sector. 5 Array of Munsell samples used to elicit colour terms. 5R 10R 5YR 10YR 5Y 10Y 5GY 10GY 5G 10G 5BG 10BG 5B 10B 5PB 10PB 5P 10P 5RP 10RP Light Dark From Davidoff, J., Davies, I. & Roberson, D. (1999) Nature, 398, 203-204 9 8 7 6 5 4 3 2 5R 10R 5YR 10YR 5Y 10Y 5GY 10GY 5G 10G 5BG 10BG 5B 10B 5PB 10PB 5P 10P 5RP 10RP Mili Mola 5 4 7 1 1 1 1 1 2 2 1 1 1 4 5 1 1 1 1 1 2 1 1 1 3 2 1 2 1 2 8 2 3 4 4 1 Distribution of Dani naming and choices of best exemplar for the 160 chip saturated array. (Rosch Heider, 1972).  9 8 7 6 5 4 3 2 5R 10R 5YR 10YR 5Y 10Y 5GY 10GY 5G 10G 5BG 10BG 5B 10B 5PB 10PB 5P 10P 5RP 10RP Pink Red Orange Yellow Brown Green Blue Purple Pink Red       Distribution of English naming for the 160 chip saturated array showing the focal points for each colour category reported by Rosch Heider (1972). 6 Tasks: • colour recognition memory • 3 types of colours: – focal: best exemplar of basic colour categories according to Berlin & Kay (1969) – internominal: middle of colour area for which no language has a name – boundary: colour at boundary between focal or internominal clusters Results: US Dani Focal 5.25 2.05 Internom. 3.22 0.47 Boundary 2.51 0.71 Mean Correct Recognition Scores The focal representatives of universal colour categories are better recognised regardless of colour words in the language. What does this mean? • The universally better recognition of focal colours was taken as evidence against the Sapir-Whorf hypothesis. • Colour perception and memorisation is independent of language. • ==> Thought is independent of language. 7 Roberson, Davies & Davidoff (2000) • Replication of Rosch-Heider’s experiments with the Berinmo (Papua- New Guinea) • 5 colour words: wapa white kel black mehi red wor yellow/orange/brown nol green-yellow/green-blue/purple Array of Munsell samples used to elicit colour terms. 5R 10R 5YR 10YR 5Y 10Y 5GY 10GY 5G 10G 5BG 10BG 5B 10B 5PB 10PB 5P 10P 5RP 10RP Light Dark From Davidoff, J., Davies, I. & Roberson, D. (1999) Nature, 398, 203-204  9 8 7 6 5 4 3 2 5R 10R 5YR 10YR 5Y 10Y 5GY 10GY 5G 10G 5BG 10BG 5B 10B 5PB 10PB 5P 10P 5RP 10RP Pink Red Orange Yellow Brown Green Blue Purple Pink Red       Distribution of English naming for the 160 chip saturated array showing the focal points for each colour category reported by Heider (1972a). From Davidoff, J., Davies, I. & Roberson, D. (1999) Nature, 398, 203-204 8 9 8 7 6 5 4 3 2 5R 10R 5YR 10YR 5Y 10Y 5GY 10GY 5G 10G 5BG 10BG 5B 10B 5PB 10PB 5P 10P 5RP 10RP Mehi Wor Nol Kel Kel Wap Wap Mehi 1 0 3 5 3 2 1 1 4 3 2 4 2 1 2 1 1 3 2 1 2 4 3 5 1 1 1 1 2 1 1 1 2 1 1 1 4 1 8 4 2 1 1 1 1 1 1 1 1 1 2 5 7 2 1 1 1 4 2 2 1 Distribution of Berinmo naming and choices of best exemplar for the 160 chip saturated array (for 25 subjects). Results: English US Berinmo Dani Focal 4.90 5.25 1.73 2.05 Internom. 4.40 3.22 0.97 0.47 Boundary 4.03 2.51 1.10 0.71 Mean Correct Recognition Scores Focal colours recognised better. Testing discriminability. • Task: “Find the chip” Result: Focal colour chips perceptually easier to discriminate! Re-test with a revised array of equally discriminable colours. 9 Results: English Berinmo Focal 4.63 1.38 Internom. 3.88 0.94 Boundary 4.50 1.32 Mean Correct Recognition Scores No advantage for focal colours in recognition. Categorical Perception Qualitatively discontinuous perception of a physical continuum. Between-category distances are perceived as greater; withincategory distances as smaller. Predictions: • English: Blue - green boundary • Berinmo: Nol - wor boundary. (Nol: green, blue, purple; wor: yellow, orange, brown, khaki) Equidistant stimuli across a category boundary: wor nol green blue English 10 Predictions: • English: Blue - green boundary • Berinmo: Nol - wor boundary. (Nol: green, blue, purple; wor: yellow, orange, brown, khaki) Equidistant stimuli across a category boundary: wor nol green blue Berinmo Results: Green-blue Nol-wor boundary boundary Berinmo 20.75 25.38 English 23.00 14.38 Mean number of choices (out of 32) which were in line with predictions. Categorical perception follows category labels in each language. What does this mean? • Colour labels in the language affect similarity judgements. • ==> Language affects thought? 11 Counterfactuals • English grammar allows subjunctive construction: “If John were to go to the hospital he would meet Mary” • Not so in Chinese: “If John is going to the hospital…but he is not going to the hospital…but if he is going he meets Mary” • Chinese poorer at counterfactual reasoning task than Americans (Bloom, 1981) Spatial reasoning • Space coded relatively (left, right, up etc.) or absolutely (north, south etc.) • Choice of coding system in reasoning tasks determined by dominant system in language (Pederson et al, 1998) Conclusion • There is some evidence that language affects thought, memory, and categorisation. • Support for weak and weakest versions of the Sapir-Whorf hypothesis 1 Higher level cognition: Judgement PSY9AC Cognition A town is served by two hospitals. In the larger hospital about 45 babies are born every day and in the smaller hospital about 15 babies are born each day. As you know, the overall number of males born is about 50%; however, the exact percentage varies from day to day. For a period of one year, each hospital recorded the number of days on which more than 60% of babies born were boys. Which hospital recorded more such days? A) The larger hospital B) The smaller hospital C) Both about the same (i.e., within 5% of each other) Kahneman & Tversky (1972) H T H T T H T T T T T T T T H T H H H H T H T H T H H T T H H T H T T H T T H H Coin Tosses 2 Cumberland River Thames Regent’s Park Points of Impact of 67 V-1 Bombs in Central London Gilovich (1991) Cumberland River Thames Regent’s Park Points of Impact of 67 V-1 Bombs in Central London Gilovich (1991) Linda is 31 years old, single, outspoken, and very bright. She has a degree in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations. Which of the following alternatives is more probable? A) Linda is a bank teller B) Linda is a bank teller and is active in the feminist movement. After Tversky & Kahneman (1983) 3 Heuristics and biases Kahneman & Tversky (1973, 1974) • Judgements of probability based on use of several “rules of thumb”: – Representativeness – Availability – Adjustment and anchoring • Reliance on these heuristics leads to systematic biases. Representativeness • Assumption that each member of a category is “representative” of that category • Assumption of homogeneity of category – “like goes with like” – Effects resemble causes – Momentous events must have momentous causes Representativeness • Insensitivity to sample size • Misconceptions of chance • Insensitivity to base rates • Misconceptions of regression 4 Neglect of base rates I have a friend who is a professor. He likes to write poetry, is rather shy, and is small in stature. Which of the following is his field: A) Chinese studies or B) Psychology? cf. Kahneman & Tversky (1973) Neglect of base rates Dick is a 30 year old single man. His hobbies include home carpentry, sailing and mathematical puzzles. Is this person more likely to be: A) an engineer or B) a lawyer? Kahneman & Tversky (1973) Neglect of base rates The following describes someone drawn from a population of 70 lawyers and 30 engineers. Dick is a 30 year old single man. His hobbies include home carpentry, sailing and mathematical puzzles. Is this person more likely to be: A) an engineer or B) a lawyer? Participants ignored the base rate 5 Neglect of base rates I’m having chest pains so I’ve got heart disease. No chest pain 0 Chest pain 10 Heart disease Neglect of base rates I’m having chest pains so I’ve got heart disease. No chest pain 0 10,000 10,000 Chest pain 10 990 1,000 Heart disease No heart disease Total Prob. of chest pain with heart disease = 1% Regression to the mean • If two variables are imperfectly related, extreme values on one variable tend to be matched, on average, with less extreme values on the other. • Tall parents tend to have tall children but not as tall (on average) as they are themselves. 6 Misconceptions of regression • People do not expect regression when it’s bound to occur – Predictions are insufficiently regressive • Regression fallacy – Explain regression with spurious causal relations Tom Cruise Anne Bancroft Joan Crawford Ricky Gervais Tony Blair George Bush Arnold Schwarzenegger Laura Dern David Beckham Rachel Griffiths Susan George Lana Turner Paul McCartney Orlando Bloom Jody Foster Kathy Bates Availability • People assess the frequency of a class or the probability of an event by the ease with which instances or occurrences can be brought to mind. 7 Availability • Biases due to retrievability of instances – Familiarity – Recency – Salience Imagine you picked someone at random from the population. Will that person be more likely to die of cause A or cause B? Cause A Cause B Homicide Appendicitis Car-train collision Drowning Measles Smallpox Botulism Asthma Appendicitis Pregnancy From Lichtenstein et al (1978) Availability • Biases due to retrievability of instances – Familiarity – Recency – Salience • Illusory covariation 8 Illusory covariation • Availability can bias judgements of the frequency with which two events co-occur • e.g., Chapman & Chapman’s (1971) Rorschach study • Events which are perceived to be strongly associated are incorrectly judged to cooccur frequently • Confirmation bias (e.g., Gilovich, 1991) Confirmation bias Thinking of best friend Thinking of boyfriend 2 Best friend rings 6 Boyfriend rings Weird how you ring whenever I’m thinking of you 9 Confirmation bias 2 2 4 Best friend rings 6 44 50 Boyfriend rings Thinking of Total best friend Thinking of boyfriend Weird how you ring whenever I’m thinking of you Excessive impact of confirmatory information Anchoring • People’s estimates seem to be biased towards some initial given starting value (an “anchor”), even when the anchor is unreliable. Tversky & Kahneman (1974) Summary • Create something out of nothing • Make too much of too little • See what we expect to see From Gilovich (1991) 1 Cognition summary PSY9AC Cognition Perception Cognition Perceptual Recognition processes Attention Memory Language Executive Processes Thinking Recognition • Object, face and word recognition • Evidence for stages – Experimental, neuropsych, imaging etc. • Comparisons between them in terms of representations and stages – Are faces special? • Applied aspects of face processing 2 Attention • Attention as a selective filter – Early vs. late selection • Visual attention – Space based vs object based – Spotlight, zoom lens etc. • Functions of attention – Solving the binding problem – Role in scene perception: change blindness Memory • Fractionation of systems STM Verbal Visuospatial LTM episodic semantic procedural Memory: remembering • Fractionation of processes and factors influencing remembering Encoding Levels of processing Retrieval Type of task: recall vs recognition Context effects and encoding specificity Incidental/intentional learning Elaboration Flashbulb memories 3 Memory: forgetting • Over life span: – Retention function – Reminiscence bump – Infantile amnesia • How we forget: – Decay – Proactive interference – Retroactive interference Language • Sentence parsing – Depth first vs breadth first parsing – Modular vs interactive – Garden paths • Language and thought – Linguistic relativity Control of cognition • Limited capacity central processor vs concept of the executive – SAS model • A single, unitary executive vs. fractionation of control – Society of mind 4 Thinking • Making judgements – Normative accounts vs. heuristics and biases Perception Cognition Perceptual Recognition processes Attention Memory Language Executive Processes Thinking Some links between themes Perception Perceptual Recognition processes Attention Memory Language Executive Processes Thinking Cognition Some links between themes 5 Perception Perceptual Recognition processes Attention Memory Language Executive Processes Thinking ? Cognition Some links between themes Perception Perceptual Recognition processes Attention Memory Language Executive Processes Thinking ? Cognition Some links between themes Perception Perceptual Recognition processes Attention Memory Language Executive Processes Thinking Cognition Some links between themes 6 Exam • Two hours • Six short answers from choice of 10 – Material from 2nd half of module – Breadth of knowledge • One essay from choice of 6 covering: – Recognition; attention; memory; language; control of cognition; judgement – Depth of knowledge and understanding Short answer example • Semantic priming This is the speeded recognition of a word, object or face when preceded by a related word, object or face than when preceded by an unrelated item. Unlike repetition priming, semantic priming is short-lived and crosses domains (e.g. words will prime pictures and vice-versa). There is debate as to whether semantic priming can be considered to be categorical (items from the same category prime each other) or associative (items which are not from the same category but which are associated - “daisy” and “chain” - prime each other). Essay • Answer question • Marshal evidence in support of answer • Critically evaluate alternatives • Conceptual understanding 1 Control of Cognition 1 Control of Cognition 46AC Cognition Dr Anna Law Control of Cognition 2 Overview Control in Simple and Complex Tasks The Central Processor The Central Executive The Supervisory Attentional System Fractionation of Control Control of Cognition 3 Control in Simple Tasks Need to configure the right task – Enable/disable module-module links – Input-output rules – Decision criteria – Preparing effectors Monitor outcome Optimise performance 2 Control of Cognition 4 Control in More Complex Tasks Configure tasks Sequencing tasks Set memory triggers Monitoring Troubleshooting Control of Cognition 5 The Central Processor View General purpose Limited Capacity Single “channel” (Broadbent, 1958) or limited attentional “resource” (Kahneman, 1973) Control of Cognition 6 Atkinson & Shiffrin’s (1971) Modal Model Parallel processing of input Info selected for entry into a short-term store Short-term store: Control processes – Selection – Rehearsal – Coding – Decision making 3 Control of Cognition 7 The Modal Model Atkinson & Shiffrin (1971) Control of Cognition 8 Problems for the Central Processor View The operating system analogy – Is control really given over to specialised processes? – Operating system seems to run concurrently with lower-level processes – The real controller is the user Simultaneous performance of two “controlled” tasks Control of Cognition 9 Dual Task Performance High level tasks need the central processor Only available to serve one input at a time Predicts strict limits on dual task performance 4 Control of Cognition 10 Spelke, Hirst & Neisser (1976) Two tasks: – Read stories – Write to dictation Initially poor After 85 hours practice (17 weeks) – Normal reading speed + comprehension – Semantic processing of dictated words Control of Cognition 11 Allport et al. (1972) Two tasks simultaneously: – Sight read piano pieces – Shadow a spoken passage Performance on both tasks together no worse than when performing each task alone Í Incompatible with a central processor bottleneck Í Suggested a multi-processor model Control of Cognition 12 The Concept of an Executive Modulates the activity of other systems rather than seizing control Involved in: – Planning – Monitoring – Maintaining connections between modules – Troubleshooting 5 Control of Cognition 13 The Central Executive of Working Memory In the Baddeley & Hitch (1974) model of working memory, a Central Executive coordinates the operation of specialised subsystems Has been criticised as a poorly-specified “homunculus” Control of Cognition 14 The Working Memory Model (Baddeley, 2000) Central Executive Visuo-spatial Sketchpad Episodic Buffer Phonological Loop 15 The SAS Model Normal & Shallice (1986) Special-Purpose Cognitive Subsystems – Object recognition, spatial processing etc. Schemata – Programs which “run” on the subsystems (e.g, overtaking, braking, catching etc) – Switch in connections between modules, set variables (what to catch etc.), modulate activity of subsystems Trigger Data Base – Conditions for activating schemata 6 The SAS Model Normal & Shallice (1986) Control of Cognition 17 The SAS Model Mechanisms of Control Contention scheduling: – Selects appropriate schemata to control behaviour Inhibition between activated schemata Í When competing for same subsystems, only the strongest wins Supervisory Attentional System (SAS): – An executive – Biases contention scheduling The SAS Model Normal & Shallice (1986) 7 Control of Cognition 19 The SAS Needed when tasks: – require planning – need troubleshooting – are ill-learned or novel – are dangerous or difficult – require overcoming a habitual response Works by top-down biasing of schemata Control of Cognition 20 Evidence for the SAS Introspection/Observation – Slips of Action (Reason, 1984) Capture Errors Cross-Talk Errors etc. Í Nicely explained by SAS model Neuropsychology – Frontal Lobe Syndrome E.g. Utilisation behaviour (Lhermitte, 1983, Shallice et al., 1989) Í Damaged SAS Control of Cognition 21 Central Executive of WM = SAS? Baddeley (1986) proposed that the SAS might be a possible model for the Central Executive of working memory But still a lack of specificity about how a unitary executive or supervisory system might work Fractionation of control processes – (Baddeley, 1996; Shallice, 2004) 8 Control of Cognition 22 Fractionation of the Executive No single central executive (e.g., Allport, 1989; Logan, 1985) The “society of mind” (Monsell, 1996) Executive control could be handled by a related but separable set of processes, rather than a single system – Evidence from neuropsychology Control of Cognition 23 Fractionation of the Executive Miyake et al. (2000) – Mental set Shifting (task-switching) – Updating and monitoring of info in WM – Inhibition of prepotent responses Logie et al. (2004) – Dual-task co-ordination More complex concepts like “planning” Some level of control needed for even the simplest tasks Control of Cognition 24 Summary The control of cognition is poorly understood Early theories emphasised a central processor or bottleneck Later concepts involved executive or supervisory systems that co-ordinated or biased lower-level systems More recently, attempts have been made to fractionate the executive into individual control processes 1 Frontal Lobe Syndrome 1 Frontal Lobe Syndrome 46AC Cognition Dr Anna Law Frontal Lobe Syndrome 2 Overview Case study: Phineas Gage General characteristics of frontal lobe damage: the frontal lobe syndrome The relationship between the frontal lobes and executive control of cognition – Does frontal lobe syndrome equate to a damaged executive/SAS? 3 Phineas Gage Harlow (1868) A railway worker in 1848 An explosion caused an iron spike to shoot right through his head He survived! But with extensive damage to frontal lobes 2 Frontal Lobe Syndrome 4 Phineas Gage Harlow (1868) Before accident…. “most efficient and capable” man. After accident... “…at times pertinaciously obstinate, yet capricious and vacillating, devising many plans of future operation which are no sooner arranged than they are abandoned.” Frontal Lobe Syndrome 5 Phineas Gage Harlow (1868) Language and memory appeared largely intact Showed general impairments in control: – Disinhibited behaviour – Antisocial – Changes in mood and personality Frontal Lobe Syndrome 6 3 Frontal Lobe Syndrome 7 Other Frontal Lobe Patients E.V.R (Eslinger & Damasio, 1985) – Unable to make decisions L.E. (Shallice et al., 1989) – Unable to inhibit action plans Í Utilisation behaviour J. (Damasio & Van Hoesen, 1983) – No spontaneous speech but could repeat words or sentences Frontal Lobe Syndrome 8 Frontal Lobe Syndrome Preserved IQ in many cases But often have problems coping with everyday life Impairment seen on tests that seem to tap “executive control” systems Shallice (1982, 1988): Frontal Lobe Syndrome = Damage to the SAS Frontal Lobe Syndrome 9 The Supervisory Attentional System (SAS) Needed when tasks: – require planning or decision making – need troubleshooting – are ill-learned or novel – are dangerous or difficult – require overcoming a habitual response Works by top-down biasing of schemata 4 The SAS Model Normal & Shallice (1986) Frontal Lobe Syndrome 11 Does frontal lobe syndrome = damage to the SAS? (Shallice, 1988) Frontal Lobe Syndrome 12 Damage to SAS Í patients unable to interrupt and change ongoing activity = perseveration 5 Perseveration Errors Luria (1966) A patient is planing a piece of wood; he goes on inertly planing until not only is there nothing left of the piece of wood but he is planing the bench beneath A patient making a speech repeats part of it over and over again A patient is asked to sign his name and does so. He is now asked to draw a figure, but instead signs his name again From Monsell (1996) 14 Wisconsin Card Sorting Test Frontal Lobe Syndrome 15 Damage to SAS Í patients should find it difficult to overcome habitual responses – Utilisation behaviours – Stroop task 6 Frontal Lobe Syndrome 16 Stroop Procedure Perret (1974) Dots: Words: Colours: • LONG BLUE • AND RED • VERY BLUE • BUT GREEN • HEAVY RED • SHORT BLUE • NEAR GREEN • WITH BLUE Frontal Lobe Syndrome 17 Damage to SAS Í patients should have problems in planning and monitoring – Verbal Fluency – Multitasking – Cognitive Estimates – Tower of London Frontal Lobe Syndrome 18 Verbal Fluency Phonemic (letter) fluency – Think of as many words as possible beginning with the letter F Semantic fluency – Think of as many types of bird as possible Requires a novel strategy/plan for retrieving items from long-term memory Patients with focal frontal lesions impaired (Henry & Crawford, 2004) 7 Frontal Lobe Syndrome 19 Shallice & Burgess, 1991 Developed 2 tests of Multitasking Six Elements Test – Attempt part of each of 6 sub-tasks in a limited time Multiple Errands Test – Run a list of errands in a shopping centre “Buy a loaf of brown bread” “Find out the name of shop likely to have the most expensive item” Frontal Lobe Syndrome 20 Cognitive Estimates Shallice & Evans (1978) What’s the length of the average person’s spine? What is the best paid occupation in Britain? What’s the height of the largest building in Britain? How many camels are there in Holland? Frontal Lobe Syndrome 21 Tower of London Test Shallice (1982) Initial Position Goal Position (no.2) Goal Position (no.6) Goal Position (no.10) 2 moves 4 moves 5 moves Patients with left frontal damage were severely impaired 8 Frontal Lobe Syndrome 22 Does frontal lobe syndrome = damage to the SAS? (Shallice, 1988) Frontal Lobe Syndrome 23 Dysexecutive Syndrome Baddeley (1986) proposed that the SAS might be a possible model for the Central Executive of working memory However, he later became cautious about equating CE functions with the frontal lobes Baddeley and Wilson (1988) proposed that the term “Dysexecutive Syndrome” should be used instead of “Frontal Lobe Syndrome” – defined by impairment in function, not location of lesions Frontal Lobe Syndrome 24 9 Frontal Lobe Syndrome 25 Fractionation of the Executive Deficits of frontal patients do not necessarily indicate a unitary executive system Dissociations in performance of “frontal” tests – (Shallice & Burgess, 1991) Poor at multitasking Good at card sort and verbal fluency – EVR (Eslinger & Damasio, 1985) Poor decision making Normal at card sorting Frontal Lobe Syndrome 26 Problems with “Frontal” or “Executive” Tests In healthy people, performance on different tests is not strongly correlated (Miyake et al., 2000) Tests suffer from “task impurity” – involve contributions from lower-level cognitive processes (Rabbitt, 1997) They have poor reliability and validity (Phillips, 1997) Frontal Lobe Syndrome 27 Review article – Andres (2003) Argued against a one-to-one link between executive processes and the frontal lobes – Executive processes involve a distributed cortical network - not only frontal lobes – Patients without any evidence of frontal damage do present with executive deficits – Patients with frontal lesions do not always show executive deficits 10 Frontal Lobe Syndrome 28 Summary Much debate about the frontal lobes An influential view is that they are responsible for executive control functions – Disorganised and disinhibited behaviour of patients – Deficits on “executive” tests Recently this has been questioned, especially as executive control itself is increasingly seen as a fractionated rather than unitary system