PSY 323: Cognition Chapter 5: Short-Term & Working Memory

Memory Memory Processes involved in retaining, retrieving, and using information about stimuli, images, events, ideas, and skills after the original information is no longer present

Modal Model of Memory Atkinson & Shiffrin (1968) Three Stage Modal Model Sensory Memory Short-Term Memory (working memory) Long-term memory (permastore)

Sensory Memory Major function is to hold info long enough so that it can be processed Sight (usually less than a second) Sound (a little longer - maybe up to 2-3 seconds)

Sensory Memory Persistence of vision: retention of the perception of light Sparkler’s trail of light Frames in film

Also referred to as “Transient Memories” Visual sensory memory The iconic store Auditory sensory memory The echoic store

Measuring Sensory Memory How big is sensory memory? Sperling (1960) Array of letters flashed quickly on a screen Participants asked to report as many as possible

Testing Iconic Memory Sperling’s whole and partial report procedures present participants with a different 3 x 4 matrix of unrelated consonants (a total of 12) for 50 ms across numerous experimental trials Here is an example: X M L T A F N B C D Z P

Demo: Get ready…

Demo: Sperling (1960 ): Full Report J M O R P Z K Y C T B U

Demo: Get ready…

Demo: Sperling (1960): Partial Report W E G D S C F

Testing Iconic Memory In the whole-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 12 letters

Testing Iconic Memory 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 approximately 82% 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 (about 38%)

Sensory Memory Whole report: participants asked to report as many as could be seen Report average of 4.5 out of 12 letters Partial report: participants heard tone which told them which row of letters to report Report average of 3.3 out of 4 letters Sperling (1960)

Iconic Memory Is an exact copy of visual information Less than a second in duration 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

Auditory Sensory Memory Several studies have shown analogous results in auditory memory… Echoic store studies often use dichotic listening

Short-term Memory Short-Term Memory (STM) Psychology 101 On Line Short-term Memory Short-Term Memory (STM) A limited capacity memory system involved in the retention of information for brief periods; it is also used to hold information retrieved from long-term memory for temporary use

Duration of STM Researchers differ saying that without maintenance rehearsal something stays in STM for between 6-30 seconds After this its either lost forever or somehow makes its way into LTM Zhang & Luck (2009) 15-20 seconds or less

STM Tasks See next slide  Brown-Peterson Distractor Task (Brown, 1958; Peterson & Peterson, 1959) Procedure Read three letters, then a number Begin counting backwards by 3’s Counting backwards prevented the rehearsal of the letters After a set time, recall three letters Results Recall drops dramatically after just a few seconds See next slide 

Brown-Peterson Distractor Task Results Peterson & Peterson (1959) 3 sec delay  recall rate 80% 18 sec delay  recall rate 12%

Can intereference occur in STM? Keppel & Underwood (1962) They saw that on the first trial, memory performance was nearly perfect As subjects participated in more trials their performance declined Their conclusion: previous trials interfered with later trials – proactive interference

Brown-Peterson Distractor Task Why the quick forgetting? Memory trace vanished because of decay during the passage of time after hearing the letters Closely spaced trials lead to poorer recall; susceptibility to interference Proactive Interference seems to be a problem Cumulative memory seems to be occurring as memory form previous lists may be hampering recall Information learned previously interferes with learning new information: seems to build up across trials

Types of Interference Proactive Interference Retroactive Interference The disruptive effect of prior learning on the recall of new information (old materials increasing the forgetting of new materials) Retroactive Interference The disruptive effect of new information on the recall of previous information (new materials increasing the forgetting of old materials) Time 1 Time 2 Test Interference Study French Study Spanish Recall Spanish Proactive Study French Study Spanish Recall French Retroactive

Capacity of STM: How many items can be held in STM Digit Span Miller (1956) 7 +/- 2 meaningful groupings George Miller (1920-2012) “The Magic Number”

How accurate is the magic number? It is accurate for relatively simple information groups digits, words, etc. Not as accurate for more complex information Example: with 3 or 4 word phrases the magic number becomes 3 to 5

How accurate is the magic number? Luck & Vogel (1997) Procedure Participant sees the first display and then indicates whether the second display is the same or different

How accurate is the magic number? Luck & Vogel (1997) Results Participants were almost perfect when the researchers presented 1-3 squares but then performance began decreasing when four or more squares were presented Interpretation People are able to retain about four items in their STM

Chunking Helps Increase Limited Capacity Ericcson et al. (1989) College student had an initial digit span of 7 After 230 one-hour training sessions for 2 years, he could remember up to 79 digits How did he do it? Combing the numbers with meaningful sets: 3 4 9 2  world record for mile (3 min 49.2 sec) 8 1 1 0  almost emergency (9 1 1) 8 9 3  very old man (89.3)

NBCADDCBSNYY (NBC) (ADD) (CBS) (NYY) Chunking Example NBCADDCBSNYY (NBC) (ADD) (CBS) (NYY)

Control Processing Active processes (effortful) that are initiated by the person Mental Rehearsal Maintenance Rehearsal Repeating things over and over Spacing effect Elaborate Rehearsal Involves thinking about how new material relates to information already stored in memory

Working Memory Refers to the system for temporarily maintaining mental representations that are relevant to the performance of a cognitive task in an activated state Reading span measures the capacity of working memory when attention must be paid to comprehension of sentences and to remembering a list of words

WM is different from STM Working memory consists of a number of parts Working memory helps us manipulate information to carry out complex tasks, not just store information Baddeley & Hitch (1974)

Models of Working Memory Baddeley & Hitch (1974) Proposed a phonological loop and a visual-spatial sketch pad coordinated by a central executive The loop stores and rehearses verbal representations whereas the sketch pad does the same for visual/spatial representations Central executive focuses and switches attention, supervises and coordinates the storage components, and retrieves representations from long-term memory

So what is WM made of? Three components to WM Baddeley & Hitch (1974)

Three Components to WM Baddeley & Hitch (1974) The central executive coordinates verbal and visual information Divide attention between different tasks Help focus your attention Baddeley & Hitch (1974)

Phonological Loop Holds verbal and auditory information STM primarily uses auditory coding Made of two parts Storage - Passive, holds information Decays in about 2 seconds without rehearsal Rehearsal - Active, repeats information in storage to prevent decay See next slide 

Phonological Loop: Phonological Similarity Effect Conrad (1964) Letters or words of similar sounds get confused See next slide 

Phonological similarity effect demo… Memorize the following words: mac can cap man map Now, write them down. Memorize the following words: pen pay cow bar rig Now, write them down. Conrad (1964)

How did you do? mac can cap man map pen pay cow bar rig People usually do better with List 2 Why? List 1 has words that sound really similar Conrad (1964)

Word-Length Effect Baddeley et al. (1984) Memory for lists of words is better for short words than for long words It takes longer to rehearse long words and to produce them during recall

Demo: Which is more difficult? Read the following words, look away, count up to 15, and recall. Beast, bronze, wife, golf, inn, limp, dirt, star Alcohol, property, amplifier, officer, gallery, mosquito, orchestra, bricklayer Baddeley et al. (1984)

The word-length effect It takes longer to rehearse long words That’s why it is difficult to memorize Baddeley et al. (1984)

Articulatory Suppression Prevent one from rehearsing items to be remembered Reduces memory span Eliminates word-length effect Reduces phonological similarity effect for reading words

Demo: Which is more difficult? Read the following words while repeating the word “the” out loud (the, the, the…), look away, count up to 15, and recall. automobile apartment syllogism basketball Read the following words while repeating the word “la” out loud (the, the, the…), look away, count up to 15, and recall. story car towel coffee swing Baddeley et al. (1984)

Phonological Loop: Articulatory suppression Articulatory suppression: Speaking interferes with the operation of the loop “the, the, the…” “la, la, la, la, la,…”

Articulatory Suppression Baddeley et al. (1984) Two word lists are spoken and must be remembered automobile apartment syllogism basketball story car towel coffee swing Second list should be easier - it’s shorter But Baddeley had subjects say the word “the” over and over again

“the, the, the, the, the…” “the, the, the…” prevents rehearsal Word-length effect is abolished Baddeley et al. (1984)

Visuospatial Sketch Pad Holds visual and spatial information; used in doing anything visual - puzzles, drawings, etc. Shepard and Metzler (1971) Mental chronometry – general idea of measuring how long it takes to carry out various cognitive tasks Task: participants saw two objects, had to indicate quickly whether the two objects were the same or different

Central Executive Pulls information from LTM and coordinates tasks Uses information from the phonological loop and visuospatial sketchpad Focuses on specific parts of task Switches attention from one part to another Attention controller

Working Memory & The Brain Prefrontal Cortex Damage Goldman & Rakic (1992) Procedure: Delayed Response Task Monkey see food reward in one of two food wells; screen is lowered; delay Holding information and then required to make a response after time delay Results No problem remembering unless prefrontal cortex is removed (only at chance levels for these monkeys) Interpretation Strong evidence that prefrontal memory is integral to working memory

Prefrontal Neurons Funahashi et al. (1989)

Credits Some of the slides in this presentation prepared with the assistance of the following web sites: www.sagepub.com/upm-data/13840_Lecture_Chapter_5.ppt http://ppt.linux5.net/g/griggs-chapter-5-memory-w155-ppt.ppt www.tamu.edu/.../Ch%205%20Short%20term%20memory.ppt http://www.scribd.com/doc/83755755/Ebooksclub-org-Cognitive-Psychology-Connecting-Mind-Research-and-Everyday-Experience-With-Coglab-Manual-3rd-Edition