Learning and forgetting - summary of chapter 6 of Cognitive Psychology by Gilhooly, K & Lyddy, F, M

Cognitive Psychology
Chapter 6
Learning and forgetting

Learning is the process of acquiring knowledge which can be retrieved to help us meet our goals.
Encoding, storage and retrieval are the three main stages involved in learning and in remembering.

Learning: encoding, storage and retrieval

The first step in learning new information is to encode that information in an internal representation in working memory.
The internal representation then needs to be processed further to develop a memory trace (a mental representation of stored information) or record in long-term memory.
Processes, such as rehearsal in which the basic representation is repeated, are presumed to strengthen the trace.
Which meaningful materials, other processes of encoding can elaborate the traces and link the traces to already stored information.

Levels of processing

Levels of processing: a theory that better learning results form deeper semantic processing which produces stronger, more elaborate memory traces that superficial level processing.
Learning needs to be intentional.
Incidental learning could be strong if the material is processed deeply.
Incidental learning: learning which takes place without any intention to learn. Learning is a by-product of attending to the material

Mnemonics

Various strategies of encoding can enhance memory performance markedly.
Such strategies to boost memory are known as mnemonics.

One key mnemonic principle is categorization. Grouping of items into familiar categories. Items grouped or organized into categories will be better recalled than unorganized lists of items.
If words are drawn from a few categories, participants tend to recall them in groups or clusters by category.
Hierarchically structured categorizations are particular beneficial for retention.

Use of images in encoding is an important aspect of many mnemonics. Us as:

• The method of loci
  A strategy in which a familiar route is imagined and images of the items to be recalled are linked to landmarks on the route. Works best when the images are seen as interacting.
• The method of interacting images
  Vivid and bizarre images are formed of the items to be recalled, interacting in some way
• The pegword method
  To be recalled items are linked by imagery to an already learned sequence list of imaginable words.
  Highly imaginable nouns linked by rhymes to the number sequence.

Dual-coding hypothesis:
Concrete words can be coded in two different ways, in a verbal code and in an imagery code.
Abstract words can only easily be coded in one way, verbal. Concrete words have two internal codes an two ways of being remembered.

Encoding specificity

The encoding specificity principle: if the context at recall is similar to the context at encoding then memory will be enhanced.
Recall will be best if the cues available at the time of testing match the context which was present in the study period.

Context dependent retrieval

Reinstating the general context in which learning took place can assist later recalled.
Context effects: when memory is better when the external environment at testing is the same as at learning.

Similar results have been found for what we might call ‘internal contexts’ in the form of physiological states brought about by psychoactive agents (state-dependent learning) or in the form of moods (mood dependent memory effect).
Mood dependent is stronger for positive moods.

Spaced versus massed trials

The spacing effect: people remember material better when the material is studied on a number of different occasions over a long period of time, rather that studied in one long period, even when the total study time is equated.

Possible explanations:

• The deficient processing view
  Massed repetitions lead to deficient processing of the second presentation. We simply do not pay much attention to the later presentations.
• The encoding variability view
  Spaced repetition is likely to cause some variability in representation. Encoding varies with the context at the study period. Under massed presentations, the corresponding memory presentations are similar and relatively indiscriminable.

Thus, the spacing effect can be linked to encoding specificity in that some of the wide range of cues associated with items at study are more likely to recur at test with spaced as against massed learning conditions.

Forgetting

Forgetting is said to occur when someone cannot retrieve information that has been previously available form memory.

The classic forgetting curve.
It measures forgetting in terms of the savings in relearning a list after various amounts of time.
Saving: a way of assessing forgetting by comparing trials needed for relearning as against trials required for original learning. If fewer trials are needed for relearning then savings have been demonstrated.

In general, the typical forgetting curve shows steep forgetting at first, followed by a gradual leveling off. The rate of forgetting is not constant but diminished over time.

Interference: occurs when remembering is disrupted by related memories.

Interference

Two types of interference:

• Proactive interference
  Occurs when previous learning impairs later learning
  The more similar the intervening learning, the greater the degree of forgetting the original learning. The interference of older learning by newer learning is a major factor of forgetting.
• Retroactive interference
  Occurs when later learning impairs memory of later learning

Paired associates learning.
Participants are presented with pairs of items at study and on test are given the first word and asked to recall the second word in each pair.
Often used in the study of learning.
Neely explained interference in terms of cues becoming associated to competing responses in the interference conditions but not in control conditions.
(Like where the car is parked. The cue is becomes associated with different locations).

Decay and consolidation

Weakening of memories due solely to the passage of time would be impaired as a possible cause of forgetting.
Decay alone cannot explain the usual forgetting curve.
Forgetting is not so much at matter of the decay of old impressions and associations as it is a matter of interference, inhibition or obliteration of the old by the new.

Effects of sleep on memory

It is generally assumed that sleep protects memory from interference, and it has been suggested that this reflects active consolidations processes the occur during sleep.
Sleep’s protective benefits are particularly pronounced if it occurs right after study.
Retrograde facilitation: the beneficial effect on memory of a period of sleep or inactivity following a study period.

Neuroscience account of sleep effects on consolidation

Long-term potentiation (LTP): the long-lasting improvement in signal transmission between two neurons that results from stimulating them at the same time.
As memories are thought of to be encoded by modification of the strength of synaptic connections, LTP is widely considered one of the major neural mechanisms that underlies learning and memory.

It seems that different phases of sleep may have different effects on memory.
REM has different effects from non-REM.
Non-REM sleep blocks the induction of hippocampal LTP without disrupting the maintenance of previously induced LTP.
While LTP can be induced during REM sleep, it cannot be induced during non-REM sleep.
As a result, it might be hypothesized that during non-REM sleep, recent memories that have begun to be consolidated through LTP are protected from interference that would occur if new memories (like dreams) began to be laid down by LTP.

Consolidation processes are important in explaining the effects of non-REM and REM sleep. It seems likely that consolidation problems also underlie patterns of forgetting in amnesia.

Retrograde amnesia

Impairment gradually and continuously reduces as memories become increasingly temporally distant from the trauma.

The medial temporal lobes, which include the hippocampus and adjacent cortex, play a critical role in the formation of new memories.
Temporally graded retrograde amnesia is very likely to be observed if the brain damage in question involves the hippocampal region.

Memory consolidate over time and the hippocampal formation plays an important role in that process.
If the hippocampal formation is damaged before the consolidation process is complete, recently formed memories that are still undergoing the consolidation process will be impaired. Older, consolidated memories will be retained, but more recent memories that have not completely consolidated will likely be lost.

Effects of alcohol and benzodiazepines

Damage to the medial temporal lobes induces permanent anterograde amnesia.
Temporary anterograde amnesia can be induces by certain drugs which can also produce retrograde facilitation. Recently formed memories are retained better than they otherwise would have been, even though new memories cannot easily be formed while in the drugged stage.
This phenomenon reinforces the view that memories consolidate over time and that much of what we forget is lost because of retrograde interference arising form ordinary mental activities.
Certain agents close the hippocampus to new input, thereby inducing temporary anterograde amnesia, without affecting the ability of the hippocampus to consolidate previously formed memories. Because new input is prevented, recently formed memories are protected from the retrograde interference that they would otherwise encounter.
These drugs acts in the same way that sleep does.

Blackout by alcohol.
Reflect a failure to encode or consolidate new information.
Alcohol intoxication does not affect retrieval of old memories after intoxication.
It results in improved memory for material studies just prior to consumption.

Alcohol facilitates recently established memories because it prevents the formation of new memories that would otherwise cause retroactive interference.
It is the recently formed memories that benefit the most, those are the most vulnerable to the effects of retroactive interference.

Retrograde facilitation has also been observed with benzodiazepines.
Same as alcohol.

Sleep, alcohol and benzodiazepines all result in retrograde enhancement of memory, and the reason seems to be that a reduced rate of memory formation during the altered state protects recently formed memories form the interference that would otherwise take place.

Functional approaches to forgetting

Intrusive memories: persistent unwanted memories of traumatic events that frequently come to mind.

Retrieval-induced forgetting (RIF)

An impaired ability to recall some items caused by earlier retrieval of related items.
The forgetting om memories apparently caused by retrieval of related memories. (one memory is not retrieved and a related memory is).
The inhibition interpretation.

Directed forgetting (DF)

Participants are instructed to forget some items but remember others.
Two variants of DF:

• Item based
  Participants are shown items to remember one at a time and after each item are told whether that item should be forgotten or retained.
  After the complete list, participants are tested on memory for all the items.
  It seems likely that participants carry out extra encoding of the to-be-remembered items when the ‘remember’ instruction is given and stop rehearsing the to-be-forgotten items when the instruction is received to ‘forget’.
• List based
  Participants are given two lists and are only told to forget the list after it has been presented and before going on to memorize the second list.
  Seems to affect accessibility rather than availability.

Think/ no-think (TNT)

Participants are instructed not to retrieve a memory even when a strong cue is present.
Not only to not say the word, but also keep the response from entering consciousness.
No think trials people showed reduced activation in the hippocampal area relative to think trials.
Hippocampal activation had been shown to be related to subjective reports of retrieval.

The TNT effect depends on the participants strategies. Only found when participants used the strategy of thinking of a different word in the don’t think conditions whether spontaneously or as a result of strategy instructions.

Everyday/ real world memory

Ecological validity: the degree to which the results of a laboratory study can be applied to a real life situation.
Two aspects:

• Representativeness: increases with the realism and naturalness of the study’s materials and tasks.
• Generalizability: the degree to which results are broadly applicable to a wide range of situations.

Flashbulb memories

A vivid memory of a dramatic event and of the circumstances in which the event was experienced or heard about.
Same as other memories, only the person is more convinced.