+ Chapter 4 Learning. + Herman Ebbinghaus First to propose an experimental study of memory,...

+

Chapter 4

Learning

+Herman Ebbinghaus

First to propose an experimental study of memory, inspiring a new science of learning and memory.

Tested a single subject: himself … for over 2 years.

To minimize the effects of previous learning, he: Studied, tested, and relearned nonsense syllables comprising

consonant–vowel–consonant combinations, e.g. WUX. Avoided making associations with real words.

He always tested himself under similar conditions, including time of day.

He aimed to determine the rate of learning and forgetting.

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+Testing the Rate of Learning

The Total Time Hypothesis: The amount learned depends on the time

spent learning

The Experiment: Each day, Ebbinghaus learned a new list of

syllables, reciting the list at a constant rate for varying numbers of repetitions.

24 hours later, he determined how many additional trials he needed to relearn the list (called savings). The more trials necessary, the worse his

memory was.

The Results: Learning was linearly related to amount of

study.

From Ebbinghaus (1885).

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+The Total Time Hypothesis

The total time hypothesis has held up as a rule of thumb for over a century. The “practice makes perfect” approach applies not

only to word learning, but also to skills like writing, chess, typing, and music.

However, there are ways that the effectiveness of studying can be maximized to get more learning from the time spent.

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+Distributed Practice

The Distributed Practice Effect: It is better to space out learning trials sparsely (thinly) across

a period of time than to mass them together into a single learning block. This leads to faster improvement rates and more lasting

retention. As distributed practice takes longer in absolute terms

(i.e. less actual training, but more days), it is not always practical or convenient.

Individuals using distributed practice often paradoxically feel as though they’re being less efficient.

The benefit is not related to fatigue with denser learning.

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+Massed Practice is a Relatively Inefficient Way to Study

Rate of learning a typing skill for a range of training schedules: 1 × 1 equals one session of 1 hour per day, 2 × 1 equals two such sessions, 1 × 2 is one session of 2 hours and 2 × 2 two 2-hour sessions. From Baddeley and Longman (1978). Copyright © 1978 Taylor & Francis. Reproduced by permission (http://www.tandf.co.uk/journals).

+The Distributed Practice Effect

Spaced presentation (i.e. study) enhances memory for a variety of materials Based on this alone, study

and test should be separated as much as possible, but …

Successfully testing yourself strengthens memories more than passively studying items The sooner an item is tested

after initial presentation, the more likely it will be recalled and strengthened

Spacing Effect Generation Effect

Microdistribution (Landauer & Bjork, 1978)

Is it better to repeatedly study and test items on a list (e.g. word pairs) in close succession or spread apart? There are competing factors:

The Solution: The Expanding Retrieval Method

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+Expanding Retrieval (Landauer & Bjork, 1978)

A flexible strategy, in which: A new item is initially tested after a short delay to ensure that it is

recallable. As the item becomes better learned, the practice–test interval is

gradually extended.

Each item should be tested at the longest interval at which it can be reliably recalled. Recall failure indicates that it should be presented after a shorter

delay. Successful recall indicates that the delay should be increased.

Optimum is about 10-20% of study time before testing. For testing after 10 days, spacing between presentations should be 1-2 days. In general, longer inter-trial delays are better than short ones.

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+The Distribution of Practice Effect

Example: Pimsleur language learning samples:http://www.cateeslanguageworld.com/pimsleur/samples.php

The optimal spacing depends on the length of the delay between learning and testing The optimum interval between learning episodes should be 10–20%

of the test delay

In general, longer inter-trial delays are preferable to shorter ones

Receiving corrective feedback after test trials is important, though it can occur after a short delay without consequence

Finding the Optimal Spacing (Pashler et al., 2007)

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+Computing Optimum Spacing of Study Sessions

First day of class

Midterm

Four months (28 days)

Optimum spacing is 10-20%, so .1 x 28 = 2.8 and .2 x 28 = 5.6 so optimal study time of each piece of information is every 2.8 to 5.6 days. This includes review of previous material not just new presentations.

Chap 1Chap 2, Review Chap 1

Chap 3, Review Chap 1-2

Chap 4 Review Chap 2-3

Chap 5, Review Chap 2-4

Chap 6, Review Ch 1, 3-5

Chap 7, Review Ch 2, 4-6

Chap 8, Review all chapters

+The Importance of Testing

Karpicke and Roediger (2008) wanted to establish the importance of testing, with four groups who studied and were tested on Swahili–English word pairs over the course of a week: Group 1 (ST): All the word pairs were repeatedly studied and tested. Group 2 (SNTN): After a word was successfully recalled, it was not

studied or tested further. Group 3 (STN): After a word pair was successfully recalled, it

dropped out of additional test rotations (they continued to be studied).

Group 4 (SNT): After a word pair was successfully recalled, it dropped out of additional study rotations (they continued to be tested).

Karpicke and Roediger (2008)

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Then, after a week’s delay (e.g., at the end of two weeks), the groups were tested on all the word pairs

Results: The rate of learning did not differ across groups during week 1 Retention over the second week, did differ, however:

Groups 1 and 4 (those that continued to be tested) recalled 80% after the delay

Groups 2 and 3 (those that did not continue testing of learned pairs) only recalled 30% after the delay

The Message: Continue to test yourself on vocabulary items you already know!

Karpicke and Roediger (2008)

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+Importance of Testing

The importance of testing for later remembering. Thepattern of learning and test trials had no effect on rate of learning, but the presence of tests had a major effect on what was remembered 1 week later. From Karpicke and Roediger (2008). Copyright © 1980 AAAS. Reprinted with permission.

SNT tests instead of presenting another study trial – STN presents a study trial instead of testing. Notice the difference.


The generation effect shows that having to come up with an answer, rather than having it provided simultaneously, leads to greater retention. This is true even if the test and the answer are only

separated by a very brief delay (Metcalf & Kornell, 2007). Multiple-choice tests enhance subsequent long-term recall

(Marsh et al., 2007). However, short-answer tests are more effective than multiple-

choice in enhancing subsequent recall.

What Type of Test is Most Effective?

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+The Importance of Feedback

Recall errors made early in training persist unless corrected with feedback.

Instructing normal, healthy participants to guess when they know that they will receive feedback yields equivalent performance on multiple-choice tests compared to those instructed NOT to guess.

Amnesic patients don’t benefit from feedback (since they can’t remember it); instead they benefit more from learning procedures that avoid errors in the first place.

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+Motivation to Learn

Unlike in animal learning studies, human participants are often intrinsically motivated to please the experimenter, prove their proficiency at the task, and to maintain interest. Nilsson (1987) demonstrated that adding cash rewards or

emphasizing social competition to further motivate participants did not affect the results of a memory task.

Motivation does have an indirect effect on learning, it helps determine: The amount of time devoted to the material. The degree of attention devoted to the material.

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+Repetition and Learning

Simple repetition of learning material is not sufficient for learning: Especially if the information is

complex or if it is not perceived as immediately useful.

Having an existing, well-formed schema for the new material allows for its easier integration into memory.

Housewives recalled the date of a radio frequency change but not the frequencies.

From Rubin and Kontis (1983). Copyright © The Psychonomic Society. Reproduced with permission.

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+Change Blindness

Change Blindness: The phenomenon in which some prominent feature

of the visual environment is dramatically changed without the perceiver apparently noticing.

This is NOT due to: A failure to take notice of the feature that is

eventually changed. The fragility of visual STM.

LTM for complex scenes is not very detailed.

http://viscog.beckman.illinois.edu/flashmovie/23.php

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+Implicit Learning

Non-Declarative or Implicit Learning: Is evident in changes in behavior, rather than

explicitly remembering information. Can be divided into three broad categories:

Classical Conditioning Priming Procedural Learning

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+Implicit Learning

Classical Conditioning: An associative learning process in which an unconditioned

stimulus (UCS) automatically produces the unconditioned response (UCR); after repeatedly pairing a neutral, conditioned stimulus (CS) with the US, the CS eventually comes to elicit a conditioned response (CR), often similar to the UR, on its own

First noted by Twitmyer (1902) in a knee reflex Pavlov (1927) was credited with its discovery in the salivary reflex in

dogs: Meat powder (UCS) causes dogs to reflexively salivate (UCR) Repeatedly presenting a bell (CS) before the meat powder (US)

results in the dogs salivating (CR) to the bell (CS) alone

Classical Conditioning

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+Pavlov’s Studies


Prior to conditioning

Conditioning

After conditioning

Neutral stimulus(tone)

(Orientation to soundbut no response)

UCS(food powder in mouth)

UCR(salivation)

Neutral stimulusCS (tone)

UCS(food powder)

+CR

(salivation)

CS(tone)

CR(salivation)

+Implicit Learning

Features/Types of Conditioning Description

Extinction If the CS is repeatedly presented without the UCS, the production of the CR gradually decreases

Backward (Trace) Conditioning When the CS follows the UCS during training, much less conditioning occurs (very weak)

Latent Inhibition Repeatedly presenting the CS alone before forming its association with the UCS impairs subsequent conditioning of the CS

Mere-Exposure Effect Simply increasing one’s exposure to a novel stimulus will increase its rated pleasantness (though not necessarily memory for detail)


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+Conditioning in Advertising

Conditioned attitude to a novel brand of toothpaste as a function of the number of conditioning trials. Participants rated the likelihood that they would choose the positively conditioned brand over the randomly associated control brand. C, conditioning; RC, random control. Data from Stewart et al. (1987).

+Implicit Learning

Priming: The ability to implicitly influence the subsequent perception

or processing of material by presenting it or a related stimulus beforehand. Involves non-conscious processing.

Occurs across all senses, as well as for verbal and visual-spatial memories – a coherent memory system.

Amnesic patients demonstrate normal priming (Warrington & Weiskrantz, 1968) – visually degraded words were recognized when subjects were asked to “guess.” Conversely, explicitly asking amnesics to remember what

they saw previously (a declarative task), results in highly impaired performance.

Priming

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+Implicit Learning

Priming Procedure Description Example

Stem Completion Provide the first few letters of a previously seen word and ask them to come up with any word that fits*

Present: STAMPTest: ST_____Result: more likely to generate “STAMP”

Word Fragment Completion

Provide only some of the letters of a previously presented word and ask what might fit*

Present: ELEPHANTTest: _L_P_A_TResult: More likely to generate “ELEPHANT”

Two Priming Tasks

*Note: To be an implicit task, no reference/requirement to remember what they saw previously is made.

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+Implicit Learning

Priming is more durable over the long term, but explicit memory is better over the short term (Tulving, Schacter, Stark, 1982). For short delays (e.g. 1 hour):

Explicit recall produces better performance than word fragment completion.

For long delays (e.g. 1 week): Word fragment completion remains effective,

whereas free recall reveals substantial forgetting.

Durability of priming

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+Implicit Learning

Types of priming: Perceptual priming

The prime and the target share physical properties Example prime: NURSE Example target: N_R_E

Answer: NURSE Sensitive to the modality and form of the stimuli

Conceptual priming The prime and the target are related semantically

Example prime: NURSE Example target: D_C_O_

Answer: DOCTOR

Priming improves when the physical conditions present during encoding are reinstated at testing.

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+Encoding Specificity & Priming

Influence of encoding semantically or physically on explicit cued recall versus implicit stem completion. Performance improves when the test conditions match the physical conditions present during encoding. Based on Graf and Mandler (1984) Experiment 3.

+Implicit Learning

Procedural Memory: Long-term memory for skills and procedures – a form of learning that

doesn’t rely on conscious strategy.

Masters’s (1992) “Choking” Study: Training: Golf putting

Half also had a concurrent demanding attentional task during training. Testing:

Half of each group was tested under stressful conditions. Results:

Learning is somewhat impaired by the concurrent task. Those trained with the concurrent task were more resistant to stress.

The concurrent task reduced reliance on explicit putting strategies, which are prone to disruption.

Procedural Learning

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+Implicit Learning (with Concurrent Task) is More Resistant to Stress

Mean number of putting shots holed as a function of skill acquisition phase (sessions 1–4) and a test phase (session 5) in the study by Masters (1992). Implicit learning led to lower performance but was more resistant to the effects of stress at test.

+Implicit Learning

Natural grammar (for one’s native language) appears to be learned implicitly, without formal training. Grammars are generative:

Grammar permits the items of the language to be combined and recombined to form nearly an infinite number of statements.

Artificial grammars are designed with arbitrary rules allowing certain combinations but not others – used to study language learning. People can learn to reliably determine whether a sequence is

grammatical, but they generally can’t explicitly state the rules of the artificial grammar (Reber, 1967).

Learning appears to generalize, suggesting that subjects have acquired the underlying rules, though there is some question about what exactly has been learned.

Learning Artificial Grammars

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+Sample Artificial Grammar

A finite state grammar of the type used by Reber to study implicit learning. Three examples of grammatically permissible sequences are shown.

+Methods of Second Language Learning

Explicitly learning grammatical rules of a language e.g. going through a grammar

workbook in Spanish class

Implicit learning in which grammatical rules are acquired simply by being surrounded by the language e.g. spending a year abroad

in Spain

Explicit Training Immersion Method

Ellis (1993; 1994) tested whether teaching grammar by example or by explicit rules is better By example: Rapid learning but no generalization Explicit rules: Good explicit knowledge of rules but no generalization Applying explicit rules to samples: Slow learning but showed generalization

Thus, the immersion method may not be a sure bet for generalized learning, although this has not been tested with exposure and learning conditions equivalent to native language learning in early childhood.

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+Implicit Learning

Could an apparent lack of explicit knowledge simply reflect difficulty in verbalizing a nonverbal task? The Teach Back Method:

After training, the learner is asked to instruct a naive participant how to perform the task.

This method appears to produce some level of explicit information transmission, but only after numerous trials.

Teach Back Method

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+Learning and Consciousness

Core Consciousness (Damasio, 1994): A continuum ranging from being fully awake and alert to deep

sleep/coma.

Is learning possible without normal consciousness? Learning tends to be better when awake and attentive. Claims for learning during sleep are unsubstantiated.

However, sleep may help consolidate previous learning. Some implicit learning under anesthesia has been reported.

Little evidence exists for explicit learning when anesthesia is correctly applied.

Thus, conscious awareness may be less necessary for implicit learning than for explicit learning.

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+Explaining the Dissociation between Implicit and Explicit Memories

Hypothesis 1: The different types of implicit learning all share a common learning mechanism.

Hypothesis 2: The only real commonality between the different types of implicit learning is the absence of episodic learning – Baddeley likes this view. Episodic learning: a system that glues together events that

we experience at the same time. This view is supported by neuroimaging evidence, which

reveals distinct brain regions underlying the various forms of implicit learning.

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+Explicit Learning and the Brain

Hebb (1949) proposed that long-term learning is based on cell assemblies: When two separate neurons are repeatedly excited in

synchrony (at the same time), the chemistry of the synapse (gap) between the neurons changes.

This makes each one more likely to have an action potential when the other does.

“Neurons that fire together wire together.”

Hebb believed that short-term learning was reflected in temporary electrical changes within existing cell assemblies.

Hebbian Learning

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Neurobiological evidence for Hebb’s idea: Bliss and Lomo (1973) repeatedly stimulated

axonal pathways, which led to lasting increases in the electrical potentials generated by post-synaptic neurons, called long-term potentiation (LTP). These changes (LTPs) are strongly represented

in the hippocampus and surrounding regions associated with long-term memory.

They also occur in the amygdala supporting emotion-based learning (classical conditioning).

Long-Term Potentiation

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Drugs that enhance synaptic transmission enhance learning, whereas drugs that block LTP tend to reduce learning. Hippocampal LTPs are blocked by a substance

known as AP5. Administering AP5 impairs rats’ spatial learning in

the Morris water maze. Hippocampal lesions (as opposed to drugs that

block LTP) cause a similar deficit.

Is LTP really the mechanism behind learning?

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+Morris Water Maze

Typical swimming paths shown by rats within a Morris water maze. Normal rats (a) rapidly acquire a direct path, as do ratswith cortical lesions (b), whereas hippocampal lesions result in a failure to learn (c). Data from Morris et al. (1982). Similarly rats with AP5 blocking LTP performed like (c) rats with hippocampal lesions, increasing with size of dose of AP5.


The neurotransmitter N-methyl-D-aspartate (NMDA) While NMDA receptors are necessary for LTP to

occur, it may not be sufficient for learning. This leaves a role for other psychological

processes and underlying brain regions, such as attention. Genetic factors also play a role.

Neurotransmitters

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Consolidation: A process whereby a temporary memory trace becomes

established, either on a molecular level or a systems level (i.e. transfer from one brain region to another brain region).

Classically thought to be interrupted by electrical brain stimulation or drugs, damaging unconsolidated memories, but: Memory traces are not necessarily lost but are just temporarily

inaccessible. Consolidated memories again become vulnerable to disruption

whenever they are recalled (reconsolidation). Such complications prompted Nadel and Moscovitch’s

multiple-trace theory, which assumes that each retrieval sets up new episodic and semantic traces.

Consolidation

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+Implicit Learning and the Brain

Participant Group Results

Normal Controls Normal fear conditioning and explicit memory for the colors

Amygdala Damaged No fear conditioning but normal explicit memory for the colors

Hippocampus Damaged Normal fear conditioning but no explicit memory for the colors

Damage to Both Areas No fear conditioning and no explicit memory

No Single System can Account for Learning

Procedure: One of the presented colors is paired with a loud sound, which induces an anxiety response (increased skin conductance) – Classical conditioning

Tests: Participants are shown the colors alone to test for a conditioned anxiety response and asked to recall the colors (which one was paired with the sound?)

Conclusion: The amygdala is important in human fear conditioningMore recent neuroimaging studies support this conclusion

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Bechara et al.

+Bechara et al.’s Findings

Control data and performance of three contrasted patients (SM, WC, and RH) studied by Bechara et al. (1995). Copyright © 1995 AAAS. Reprinted with permission.

SM = bilateral amygdala damageWC = hippocampal damage but intact amygdalaRH = damage to both hippocampus and amygdala

Conditioning of anxiety to the blue slide accompanied by loud noise is affected by damage to the amydala (left). Declarative learning (explicit) for colors is affected by damage to the hippocampus (right). Control stimuli are shown in the center. Control subjects (top) show both forms of learned response.


Schott et al.’s (2005) fMRI study found different patterns of activity with explicit vs implicit processing in a stem completion task.

During learning, subjects were asked to count the syllables in 160 words. Under explicit instructions (try to remember the words) they

found increased blood flow in both hemispheres in the parietal, temporal, and frontal regions.

Under implicit instructions (say the first word that comes to mind) they found decreased blood flow in the left fusiform gyrus and in the frontal and occipital regions.

This reduction likely reflects easier processing of primed words.

Different Components are Associated with Priming

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Serial Reaction Time Task: A well-studied task of procedural, implicit learning Task – Four buttons and four lights:

Press the button that corresponds to the light that is on. A pattern is introduced to the button pressing sequence,

leading to faster performance, then the pattern is changed. Results:

Both normal and amnesic patients learn the patterns and both slow down when the pattern is changed (not relevant).

Simultaneously performing an attentionally demanding task eliminates conscious pattern awareness (explicit) without eliminating the learning effect. The task becomes implicit.

Procedural Learning

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Neuroimaging the Serial Reaction Time Task (Grafton et al., 1995): Implicit condition (dual-tasking):

Learning-related changes occur in the left motor and supplementary motor cortex.

Single-task condition (permitting greater pattern awareness): Learning-related changes occur in the right

prefrontal cortex, premotor cortex, and the right temporal lobe, as in other previous studies.

Procedural Learning

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+ Chapter 4 Learning. + Herman Ebbinghaus First to propose an experimental study of memory,...

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