Memory (1) Atkinson & Shiffrin (1968) Model of Memory Visual Sensory Store It appears that our visual system is able to hold a great deal of information but that if we do not attend to this information it will be rapidly lost. X M R J C N K P V F L B Demo at: http://www.dualtask.org/ Sperling (1960) Presented array consisting of three rows of four letters Subjects were cued to report part of display 1
Visual Sensory Memory Mean number of words reported Vary the delay of cue in partial report After one second, performance reached asymptote Delay of cue (in seconds) Iconic Memory Sperling s experiments indicate the existence of a brief visual sensory memory known as iconic memory or iconic store Information decays rapidly unless attention is transfers items to short-term memory Analogous auditory store: echoic store Atkinson & Shiffrin (1968) Model of Memory Short-term memory (STM) is a limited capacity store for information -- place to rehearse new information from sensory buffers Items need to be rehearsed in short-term memory before entering long-term memory (LTM) Probability of encoding in LTM directly related to time in STM 2
a memory test... DOORKNOB CONCRETE SUNSHINE SOFTBALL RAILROAD CURTAIN HAMMER SUBWAY DOCTOR CANDLE TURKEY COFFEE FOLDER PLAYER LETTER PENCIL TOWEL KITTEN MAPLE TABLE Serial Position Effects no distractor task distractor task In free recall, more items are recalled from start of list (primacy effect) and end of the list (recency effect) Distractor task (e.g. counting) after last item removes recency effect Serial Position Effects Explanation from Atkinson and Shiffrin (1968) model: Early items can be rehearsed more often more likely to be transferred to long-term memory Last items of list are still in short-term memory (with no distractor task) they can be read out easily from short-term memory 3
Forgetting over time in short-term memory. Peterson and Peterson (1959) Baddeley s working memory system. Baddeley proposed replacing unitary short-term store with working memory model with multiple components: Phonological loop Visuo-spatial sketchpad Central executive (ignore the episodic buffer) Baddeley and Hitch (1974) Baddeley (1986) Phonological Loop (a.k.a. articulatory loop) Stores a limited number of sounds number of words is limited by pronunciation time, not number of items Experiment: LIST 1: Burma Greece Tibet Iceland Malta Laos LIST 2: Switzerland Nicaragua Afghanistan Venezuela Philippines Madagascar Word length effect mean number of words recalled in order (list 1 4.2 words; list 2 2.8 words) Phonological loop stores 1.5-2 seconds worth of words 4
Two routes to phonological loop Visual presentation Auditory presentation Articulatory control process Speech code Phonological loop Articulatory control process converts visually presented words into a speech code Articulatory suppression (e.g. saying the all the time) disrupts phonological loop Prediction: Word length effect depends on phonological loop With articulatory suppression, visually presented items should not display word length effect Immediate word recall as a function of modality of presentation (visual vs. auditory), presence vs. absence of articulatory suppression, and word length. Baddeley et al. (1975). Working memory and Language Differences Different languages have different #syllables per digit Therefore, recall for numbers should be different across languages E.g. memory for English number sequences is better than Spanish or Arabic sequences (Naveh-Benjamin & Ayres, 1986) 5
Evaluation of the Evidence for the Phonological Loop Accounts for phonological similarity and the word-length effect Support from neuroimaging studies Baddeley, Gathercole, and Papagno (1998) Its function may be to learn new words Encoding & Retrieval Effects Levels of Processing (Craik & Lockhart, 1972) Levels of processing effect: Deeper levels of processing (e.g., emphasizing meaning) leads to better recall. 6
Encoding Specificity Principle Recollection performance depends upon the interaction between the properties of the encoded event and the properties of the retrieval information Context Change Information learned in a particular context is better recalled if recall takes place in the same context Similarly, information learned in a particular context may be difficult to recall in a dramatically different context Godden & Baddeley (1975, 1980) Memory experiment with deep-sea divers Deep-sea divers learned words either on land or underwater They then performed a recall or recognition test on land or underwater 7
Mood-dependent Memory Easier to remember happy memories in a happy state and sad memories in a sad state. Subjects study positive or negative words in normal state. Test in positive or negative induced states. mood primes certain memory contents Kenealy (1997). State-dependent recall Does physical state matter? Eich et al. (1975): study while smoking normal or marijuana cigarette. Test words under same or different physical condition Forgetting 8
Forgetting Functions Ebbinghaus (1885/1913): Forgetting over time as indexed by reduced savings. Most forgetting functions show: Negative acceleration Rate of change gets smaller and smaller with delay Power law of forgetting Why do we forget? Forgetting Some possibilities: Memory has disappeared decay theory Memory is still there but we can t retrieve it repression inhibition theory interference theory What is Repression? Something happens that is so shocking that the mind grabs hold of the memory and pushes it underground, into some inaccessible corner of the unconscious. - Loftus (1993) Some self-help book ( Courage to Heal ) relate repressed memories to sexual abuse 9
Recovered memory vs. False Memory How do we know whether repressed memories are accurate? In some cases, traumatic information is misremembered or simply made up Loftus has been involved in many cases Points out problems of hypnosis suggestive questioning dream interpretations Elizabeth Loftus False Memory in the Lab Deese, Roediger, McDermott paradigm Study the following words Recall test... Recognition memory test SLUMBER BLANKET DROWSY SNOOZE DREAM AWAKE SNORE PEACE TIRED YAWN DOZE REST BED NAP Use ratings 1) sure new 2) probably new 3) probably old 4) sure old TEST: COFFEE SNORE SLEEP REST Results Critical lure ( sleep ) are words not presented but similar to studied words. These words are often falsely recalled (sleep: 61% of Ss.) Recognition memory results proportion of items classified with confidence levels: confidence rating 4 3 2 1 studied items.75.11.09.05 not studied unrelated.00.02.18.80 critical lure.58.26.08.08 (e.g. REST ) (e.g. COFFEE ) (e.g. SLEEP ) 10
Subjects reporting recovered memories are more vulnerable to false memories False recognition of words not presented in four groups of women with lists containing eight associates. Clancy et al. (2000) Proactive and retroactive interference Inhibitory mechanisms in Forgetting Cued recall as a function of the number of times the cues had been presented before for recall (respond condition) or for suppression (suppress condition). Anderson and Green (2001) 11