Attention and Memory

Attention I

Visual attention operates through both automatic and effortful processes Parallel processing

We automatically process all stimuli in a display when we’re paying attention to only a single dimension (e.g., color)

This allows us to quickly identify a target (i.e., it “pops out”), regardless of the number of distractors

Serial processing We need to engage slow, effortful search

processes when asked to identify targets defined by the conjunction of two dimensions (e.g., color and letter identity)

Attention II Attention allows us to select a single source of

auditory stimulation from amongst many possible sources and ignore all other incoming messages That is, attention functions like a filter

Conversely, we’re not very good at attending to more than one auditory message at a time We do process some unattended information, but in

a weaker form than we process attended information Unattended, but weakly processed, information can

grab your attention when that information is relevant to your goals

The cocktail party phenomenon

Attention III Change blindness

We often miss large objects in our visual field when we are attending to something else

Although most people do not believe they can fail to see large objects right in front of them, numerous studies show this is the case

Information-Processing Model of Memory

Sensory memory: it’s purpose is to hold an internal copy of physical information just long enough for the system to select something in particular to attend to; that information then gets transferred to . . .

STM: our conscious workspace Processes that control the flow and makeup of

information have their locus in STM (e.g., coding, rehearsal, retrieval strategies…)

Sensory memoryRepresentational format: Modality-

specific Iconic memory: visual sensory memoryEchoic memory: auditory sensory memoryHaptic memory: touch sensory memory

Duration Iconic memory: 250 msEchoic memory: 2-3 seconds

Capacity: Modality-dependentForgetting: Information decays if not

further processed

Testing the duration and capacity of iconic memory

A letter array is displayed for 50 ms

In the whole report condition, subjects try to report all the letters

In the partial report condition, subjects report only a single row of letters

Duration and capacity of iconic memory

Short-term memoryDuration: 20 sec when you are distracted and

can’t rehearse Unlimited when maintaining information through

repetition that you want to remember, like a phone number; termed “maintenance rehearsal”

Format: Visual verbal stimuli are stored in STM in an acoustic format Sound-alike errors: when they can’t remember, people

might say V instead of E, but not F instead of E.Capacity: The magical number 7+2

Chunking (1 4 9 2 1 7 7 6 1 9 4 5) Expertise

Retrieval: We retrieve information from STM by using a serial exhaustive search, rather than a serial self-terminating search

Forgetting from short-term memory

Decay theory of forgetting Memory traces dissipate as time passes and those

memories are not used (see sensory memory) Interference theory of forgetting

Memories are lost when they are bumped out or replaced by the formation of new memories

Experiment (for the result, see the next slide) Some subjects sees 12 items, at a rate of 1 item per

second. Total time: 12 seconds Other subjects also see 12 items, but at a rate of 4

items per second. Total time: 3 seconds. Decay theory predicts more forgetting in the first

condition because more time has gone by. Interference theory predicts equal forgetting in both

conditions because the same number of new memories are being formed.

Support for the interference theory of forgetting in STM

Working Memory STM was described as a

single system responsible for information flow and control

However, STM is also used for comprehension of language, problem solving, and visual imagery (e.g., mental rotation task)

Baddeley revamped the idea of STM and renamed it “working memory”

Working memory is a set of independent subsystems that share attentional resources

Some working memory findings

Memory span task: listen to simple elements and immediately report in the order of their presentation

K.F.: memory span is impaired, but IQ is spared Dual task methodology: have subjects do two tasks concurrently,

each of which taxes the interdependent systems (e.g., the auditory working memory slave system and the central executive)

Findings (1) As auditory working memory load increases from saying

“the the the …” (concurrent articulation task), to saying “1 2 3 4”, to holding six random digits in memory, reasoning task performance decreases

(2) If subjects do a memory span task and a concurrent articulation task, for which auditory working memory is responsible, memory span performance decreases

(3) Concurrent articulation eliminates sound-alike errors for visually presented materials because the scratch-pad is used instead

(4) Concurrent articulation does NOT affect memory span for visual objects that cannot be named because storage of the visual objects does not require auditory working memory

(5) Word-length effect: Memory span is shorter for longer words because longer words more quickly consume the limited resources of auditory working memory

Mental rotation in visuo-spatial working memory

Subjects were asked whether the letter was a normal R or a mirror-reversed R.

The farther away from vertical, the longer it took for the subjects to decide.

Conclusion: Subjects rotate a mental image of the stimulus to it’s vertical position before deciding.

Serial position effect Since we cannot directly observe them, how do

we know these two mental structures -- called STM and LTM -- actually exist?

Experiment All subjects are presented 15 words, one at a time,

for 2 seconds each. Some subjects are asked, immediately after the

words have been presented, to recall as many words as they can, in any order.

Serial position effect Memory performance is better for the first few words

(the “primacy effect”) and the last few words (the “recency effect”) that have been presented.

For other subjects, there is a delay of 30 seconds after the list has been presented.

During this delay, the subject may, for example, be asked to count backwards by 4’s from 569.

See next slide for result

Short-term vs. long term memory

The 30 s delay eliminated the recency effect, but did not impair the primacy effect.

This indicated that the recency effect must be due to STM, while the primacy effect must be due to LTM.

Long-term memory (LTM)

Memory for information that is no longer being rehearsed. If a person is distracted for a couple minutes from rehearsing

a new phone number, yet remembers the number, then it must have been stored in LTM.

Capacity: infinite Duration: permanent Forgetting: retrieval failure

Memories are available, but not necessarily accessible Format: meaning (semantic) and visual (episodic)

At least for explicit long-term memory You’re using your explicit long-term memory when you

intentionally retrieve information from a specific episode (episodic memory) or you intentionally retrieve a fact (semantic memory)

You’re using your implicit long-term memory when you unintentionally retrieve information from a specific episode and the retrieval of that information affects your current behavior

See slides 19, 21, and 22.

Long-term memoryThree key phases of the LTM

processEncoding

The mental processes we use to process information determine the strength and longevity of memory for that information.

StorageThere are many different types of long-

term memory.Retrieval

The circumstances under which one tries to retrieve memories, such as the nature of the memory test, influence the success of that retrieval.

LTM Systems

Declarative (Explicit) Long-Term Memory

Conscious retrieval and declaration of past events and known factsWe often retrieve information from LTM into

STM and then consciously respond in a particular manner

Two forms of declarative memoryEpisodic memory and semantic memory

Episodic memory Includes where, when, and to whom

something happened Reexperiencing, often in visual terms, of a

past event

Nondeclarative (implicit) memory

Unconscious (automatic) retrieval of information that influences behavior; responses are, in some respects, not mediated by STM

Skills and habits: reading, typing, bike riding, tying shoes, brushing teeth, washing dishes

Priming: any influence of a single past episode on current behavior that occurs without a person’s intentional retrieval or awareness

Simple conditioning: cat and can openerNonassociative learning: Habituation and

sensitization

Explicit vs. Implicit memory

Amnesic patients (like H. M.) and normal controls were tested for memory for words that had been previously studied

Amnesics performed poorly on the explicit memory tasks

Amnesic performance on implicit memory tasks was like that for control subjects

Conclusion: Amnesics can form memories for studied words – at least implicit memories – even though they can’t tell you what words they’ve studied

Encoding into (explicit) LTM

Four factors affecting the strength of (explicit) LTM1) Elaborative rehearsal (processing information for

meaning) promotes better LTM for facts than maintenance rehearsal (i.e., rote rehearsal or repetition)

2) Regardless of how you rehearse, spaced rehearsal is better than massed rehearsal It’s better to study 1 hour of information for an hour at 3

different times than for 3 hours all at one time

3) Dividing attention during encoding impairs LTM4) Use of imagery to code information in a visual

format also promotes better LTM Picture superiority effect: pictures are remembered better

than words

Semantic memory: Schemas

Schema: Knowledge representations, built through integrating similar experiences across time, which allow us to predict the nature of repeated activities (e.g., birthday parties) and environments (e.g., offices)

Schemas are used to construct long-term memories of the stimulus at encoding and to reconstruct long-term memories at retrieval Sometimes this can be beneficial, as in the

following passage from Bransford & Johnson (1972)

Sometimes this can be costly, as in the following Brewer & Treyens (1981) picture of the office

Read this passage before going to the next

slide The procedure is actually quite simple. First you

arrange items into different groups. Of course one pile may be sufficient depending on how much there is to do. If you have to go somewhere else due to lack of facilities that is the next step; otherwise, you are pretty well set. It is important not to overdo things. That is, it is better to do too few things at once than too many. In the short run this may not seem important but complications can easily arise. A mistake can be expensive as well. At first, the whole procedure will seem complicated. Soon, however, it will become just another facet of life. It is difficult to foresee any end to the necessity for this task in the immediate future, but then, one never can tell. After the procedure is completed one arranges the materials into different groups again. Then they can be put into their appropriate places. Eventually they will be used once more and the whole cycle will then have to be repeated. However, that is part of life.

Schema benefits

When subjects read the preceding passage without a title or when subjects were given a title to the passage after they had read it, comprehension scores and recall scores were low.

However, subjects given the title “Washing Clothes” before reading the passage scored twice as well in both comprehension and recall tests.

Study this picture for 30 s before going to the next slide

List as many objects as you can recall from the photograph you just saw.

Schema Costs

Many subjects recall seeing books in the picture of the office, when there are no books in the picture.

Another exampleRoediger & McDermott (1995)

Present subjects with lists of words (e.g., bed, rest, awake, tired, dream, wake, night, blanket, doze, slumber, snore, pillow, peace, yawn, and drowsy)

Many subjects recall having heard the word “sleep” in the list, even though it was not presented

Semantic memory I Semantic memories are knowledge

representations that are built through integrating similar experiences across time Each time you are told that the sun rises in the east

leaves an episodic memory of that event But once you have many episodic memories of being

told that fact, then you forget the episodes in which you learned that fact and you just remember the fact itself

This process is sometimes termed “abstraction” and the memory left is sometimes described as an “abstract” form of memory

Many different types of semantic memory Words and their meanings Facts: “George Washington’s face is on a $1 bill.” Categories: “A canary is a type of bird.” Schemas (see slides 24-29 for explanation)

Semantic Memory II: Semantic Networks

Our semantic memory is organized by meaning, like a thesaurus In contrast, a dictionary is

organized alphabetically Each concept is

represented as a node When the word “red” is

presented, the node for red becomes activated and, if that activation is sufficient, you Become conscious of that

word Become conscious of the

meaning of that word Are able to say that word or

respond to that word

Semantic Memory IIISpreading activation

When red becomes activated, the activation spreads from red to other concepts that are connected to red

Three examples of spreading activation at work Free association

If you’re asked to say the first word that comes to mind when you’re presented the word red, you’ll say blood or roses or fire engine or apple or . . .; but you won’t say words that are unrelated to red

Automatic activation of task relevant knowledge When someone says to you, “Please set the table for dinner.”,

there are many things left unsaid, such as what to set on the table, in what arrangement to set those things, how many places to set, etc. Your semantic memory fills in that missing information when activation spreads from table and dinner to related concepts.

Semantic priming (see next slide)

Semantic Memory IV: Semantic Priming

Semantic priming Imagine a task where you are presented two words in

succession and your task is to say just the second word; the experimenter is going to measure how long it takes you to say the second word

If a word unrelated to red, like the word box, is presented before the word red, you will be relatively slow to say the word red (it will take you about ½ sec)

However, if a word related to red, like the word apple, is presented before the word red, you will be relatively fast to say the word red (it will take you about 1/3 sec)

The difference in speed is called a semantic priming effect The reason you’re faster to say red after apple than after box

is because the activation of apple spread to red and, as a result, red already had a head start when the word red was actually presented.

Encoding-Retrieval Similarity

Enhancing the similarity between conditions at study and test can improve the rate at which information is successfully retrieved from LTM. The physical environment (i.e., environmental context) The stimulus environment

Encoding specificity principle

Emotional state (mood) Physiological state (drugs) Psychological state (depression) Cognitive processes that are involved in processing

information Transfer-appropriate processing

Searching for the engram I

Engram: physical site of memory storage The medial (i.e., middle) section of the temporal

lobes is important for many aspects of declarative memory

The medial temporal lobe includes cortical structures, such as the rhinal cortex, and subcortical structures, such as the hippocampus and amygdala

Consolidation Transfer of information from short-term to long-term memory

Reconsolidation After you retrieve a memory from LTM, you must re-store that

memory back into LTM When you re-store a memory back into LTM, it is often altered

by the mental environment into which it had been retrieved Spatial memory

Taxi drivers, especially experienced ones, have a larger hippocampus than people that do not drive taxis

Brain and Memory The limbic system is

critical for memory formation and recall Hippocampus:

Critical for forming new explicit (conscious) memories

Amygdala: Important role in emotional memories

H.M.’s hippocampus was removed in both hemispheres and he suffered from anterograde amnesia

H.M.’s surgery

Searching for the engram II

The frontal lobes are also important for many aspects of memoryDamage to the frontal lobes impairs

Memory for the time sequence of eventsMemory for the source of information (i.e., where,

when, and from whom information was learned)The ability to deeply process information (i.e.,

process it for its meaning)Working memory and leads to an inability to

follow a planned sequence of steps, such as using a recipe to bake a cake

Searching for the engram III

The amygdala plays an important role in memory It does so by controlling the effects of memory

modulating neurotransmitters, such as norepinephrine

This is especially true during events associated with reward, fear or other emotions, and arousal

These events cause an increase in norepinephrine and an increase in the strength and durability of memory

Occasionally, these processes can produce overstrong memories or can “burn these events into memory”

Often, patients with post-traumatic stress disorder (PTSD), cannot forget events that they would like to forget

Drugs (e.g., propranolol) that block norepinephrine receptors reduce the duration and strength of emotional memories

Forgetting: The three sins

Transience Forgetting over time

Ebbinhaus’s forgetting curve (see next slide) Decay vs. interference

Interference! (see slides 10 & 11) Types of interference

Proactive vs. retroactive (see slide 42)

Absentmindedness Inattentive or shallow encoding of events

Change blindness Blocking

A temporary inability to remember something that is known because some other, similar, information is interfering with your memory

Broussard Park? Bourgeois Park? No, it’s Burroughs Park! Tip-of-the-tongue phenomenon

Ebbinghaus’s Forgetting Curve

Over the first three days, the rate of forgetting is very high % correct drops from

57% to 25% Over the next 27

days, the rate of forgetting is very low % correct drops from

25% to 21% In summary, the rate

of forgetting is initially very high, but becomes very low

Interference and Forgetting

Distortion: The sins of persistence and misattribution

Persistence The resurgence of unwanted memories that we

would like to forget See slide 39 for the role of the amygdala and norepinephrine

in creating such memories Misattribution of source (and source amnesia)

The source of information Knowing who told you something (or when, where, and how

you learned something) is important for evaluating that information

We often misremember the source of information (source misattribution) or forget the source of information (source amnesia) and, when we do so, this leads us to evaluate that information differently

The false fame effect The sleeper effect Cryptomnesia: Unintentional plagiarism False memories

Distortion: The sin of suggestibility and the misinformation effect Suggestibility

The misinformation effect (Loftus) Subjects are shown a slide show in which a Datsun runs a

stop sign and hits a pedestrian. Later they are asked “Did another car pass the Datsun as it

reached the yield sign?” Later, 30% more of these subjects incorrectly said that they

had been shown a slide with a yield sign than if they had not been asked the “leading question”, many with a high degree of confidence.

The misinformation effect implies that eyewitness testimony many often be unreliable

For the first 130 people nationwide whose guilty verdict was overturned because of DNA evidence, mistaken eyewitness identification played a role in over 75% of the cases.

http://www.innocenceproject.org/understand/ Eyewitnesses that are wrong are often just as

confident, and sometimes even more confident, than eyewitnesses that are correct

Distortion: The sin of suggestibility and illusory

memories Illusory memories

Students (N = 24) were presented a booklet in which there were four stories of childhood events.

Three of these stories were true. The three true stories had been gathered by

previously contacting the family of the student. One of the stories, about being lost in a mall,

was false. Subjects were asked to try to remember these

events and to describe what they remembered in detail.

If they didn’t remember, they were told to say so. After first reading the booklet, 7 of 24 subjects

“remembered” being lost in the mall. In follow-up interviews, 6 of 24 subjects

continued to remember being lost in in the mall.

Distortion: Implications of illusory memories

Recovered memories or false memories? According to Freud, repressed memories are

memories of (typically) traumatic events that people have forced from their conscious memory into their unconscious

People sometimes claim to recall traumatic events (such as childhood sex abuse) after having forgotten these events for many years

If these events really occurred, were forgotten, and were later remembered, then these are called recovered memories.

If the memories of these events were really the product of suggestions made by an unwitting therapist to the patient, then these are called false memories (a special type of illusory memory).

Distortion: The sin of bias

People’s memories of their past attitudes, behaviors, or knowledge are often adjusted (biased) to be consistent with their current attitudes, behaviors, or knowledge. Subjects who are newly persuaded of the value of

brushing their teeth report that they brushed their teeth more often in the past two weeks than those that were not persuaded (Ross, 1989).

“I really knew all along how important it was to brush my teeth and, in fact, I’ve been doing so.”

“It is common for caterpillars to become butterflies and then to maintain that in their youth they had been little butterflies. Maturation makes liars of us all,” (Vaillant, 1977).

Other important memory concepts

Flashbulb memories Very clear, visual, detailed memories of a new, important, emotional

event. They are not necessarily 100% accurate, but they are more accurate

than memories for everyday events. Autobiographical memory

As we age, we tend to remember most our adolescence and early adulthood

We especially remember transitional firsts, such as 1st and 4th years of college

Prospective memory Memory for things that need to be done in the future

Remembering to do some thing at a particular time and remembering what to do at that time

Keeping the script for the to-be-done activity in an activated state helps prospective memory

Metamemory People’s knowledge of their own memory skills and abilities

The accuracy with which people guess how likely it is that they will remember something or how effective some memory strategy or learning strategy may be for them

Your metamemory has failed you when you think you’ve studied enough for an exam, but then do poorly.