S1W10Mem Flashcards
Interference
Memories acquired on different occasions interfere with each other.
Similarity between the memories affects interference.
Retroactive interference (acting backwards).
Proactive interference (acting forwards).
Decay
Simplest explanation for forgetting of long term memories.
Passive decay of a memory trace.
Directed forgetting definition
Impaired long-term memory triggered by instructions to forget information that has been presented for learning.
The Directed Forgetting (DF) paradigm
Study Phase:
o Participants shown words and instructed to either remember or forget
Test Phase:
o Tested on recognition of study words (which words are old or new) or free recall of the words.
Directed Forgetting Effect (DFE)
A high DFE means successful completion of task.
Number of words that were supposed to be forgotten but weren’t = TBF-R
Number of words that were supposed to be remembered but weren’t = TBR-R
DFE = TBR-R – TBF-R
Consistently shows significantly greater memory for TBR words than TBF words.
Selective Rehearsal
A mechanism of DF.
TBR subjected to more elaborative processing and more rehearsal than TBF.
TBR memory traces are strengthened, while TBF traces decay.
Active Suppression
A mechanism of DF.
TBF instruction leads to inhibitory mechanisms which stop further processing of TBF items.
Suppress their memory to below-baseline levels.
McGeoch (1932) - decay
Decay theories are invalid because time itself is does not cause forgetting.
Argued from this that interference is the only forgetting mechanism.
But although interference is a common cause of forgetting, decay does still occur.
Paz-Caballero et al (2004) - DF
Looked at ERPs during the study phase of directed forgetting trials.
Looked at brain activity happening in response to the remember and forget cue, in participants with high/low DFE.
Results:
Participants with high DFEs (do the task correctly) showed:
Early positive activation to forgetting cue: frontal inhibition mechanisms are used by participants that were able to forget words.
Late positive activation to remember cue (300-600ms): shows activation of rehearsing process.
As it is in posterior regions (visuospatial sketchpad), it may show re-activation of the visual trace of the word.
Hauswald et al (2011) - effect of valance on DF
• There was a significant DFE for neutral photos, but the DFE disappeared for negative photos.
Shows that negative information is harder to forget than neutral information.
ERP effect of valance on DF
Before the cues:
o ERP to the negative pictures was more positive over parietal regions than the neutral pictures
o Suggests deeper processing of negative pictures
Forgetting cue:
o ERP larger for neutral than negative pictures in frontal regions
o Amplitude of wave correlated with DFE
o Greater positive waveform was associated with more successful forgetting
DF and valance conclusion
Negative images are processed more deeply than neutral (increased parietal positivity for negative pictures).
Suppression is less successful (decreased frontal positivity) in response to the forget cue for negative pictures.
Explicit Memory
Conscious recollection of previous experiences.
Assessed with recall and recognition tasks that require retrieval from a specific episode.
Implicit Memory
Refers to learning without awareness or skills that have been learned with awareness, but are now performed without.
Assessed with tasks that do not require conscious recollection of episodes.
Brain and explicit memory
Heavily dependent on the temporal lobes.
Particularly the medial temporal lobe (hippocampus and parahippocampal gyrus).
Divided into:
Semantic – names, facts
Episodic – events in own past
Patient H.M
Bilateral removal of temporal lobes: Amygdala, Entorhinal Cortex & some Hippocampus.
STM and Implicit LTM were intact.
Unable to make new Explicit memories (anterograde amnesia).
Suggests connection between Hippocampus, Entorhinal Cortex and Neocortex are crucial for explicit LTM
Implicit Memory and the brain
Supported by a wide network (non-unitary).
Often supported by the cortex (depending on mode of info).
Can be divided into:
Priming
Procedural Learning (skills & habits)
Associative Learning (e.g. conditioning)
Non-Associative Learning (e.g. habituation)
Word-stem completion tasks
Tests priming (implicit memory)
Study phase: shown list of words.
Test phase: given stems ‘ta-, so-‘ and asked to complete them to make a word.
Serial reaction time task
Tests procedural learning (implicit memory)
Asterisk appears in one of 4 boxes on screen.
Press corresponding button as quick as possible.
Baseline trials: repeats in a random order.
Implicit learning trials: shape positions in a sequence for twelve trials.
Baseline and Implicit Learning trials alternate.
Implicit learning is shown through a decreased reaction time to IL blocks compared to B blocks, as the sequence is learned over time.
Squire et al (1992): PET of word stem completion
Subjects studied a list of 15 words which were presented one at a time
Rated how much they liked the words.
Memory – Baseline:
Increase blood to Right Posterior Medial Temporal Lobe including Hippocampus and Hippocampal Gyrus.
Increased activation of right Prefrontal Cortex in memory.
Priming – Baseline:
Decrease blood to Right Occipital Cortex
Some Hippocampal activation
Decreased activation of Right Occipital Cortex in priming
Rauch et al (1997): serial reaction time fMRI
Increased activation in the right Striatum during IL compared with baseline.
For participants who showed the greatest amount of IL, activation in the Right Putamen was correlated with the decrease in RT
Patient L.H
Removal of Inferior Temporal Gyrus and Fusiform Gyrus.
Severe damage to Parietal and Occipital Lobes.
Couldn’t recognise faces but could recognise individuals by their voice (visuoperceptual impairment).
H.M vs. L.H (Keane et al., (1995)
H.M and controls okay at perceptual priming but L.H was impaired (implicit).
L.H and controls okay with explicit memory but H.M was impaired.
L.H’s priming impairment was restricted to perceptual priming as conceptual priming was okay.
Shows that implicit and explicit memory are independent.
There may also be independence between different types of priming.
Different types of priming
Priming – exposure to a stimulus influences the response to a later stimulus.
Perceptual – items with similar forms (completion of words in a word stem test).
Conceptual – items with similar meanings (chair and table put in the same category)
Advantages of neuropsychology
Show which brain areas are necessary for different functions.
Tell us what processes are separable e.g. implicit and explicit memory.
Disadvantages of neuropsychology
Individual differences in performance.
Effects of brain plasticity (compensation).
Potential widespread damage that can’t be seen.
Variability/sensitivity of tests.
