PSYC 350: Human Memory (Unit 8)

Forgetting

Forgetting (Wixted)

The inability to access information that was successfully encoded and could previously be retrieved by the same retrieval cue

The seven sins of memory

Sins of omission: transience, absentmindedness, blocking
Sins of commission: misattribution, suggestibility, bias, persistence

Sins of omission

memory failure that occurs because a process is not performed

Sins of commission

memory failure that occurs because some error occurs

Transience

The general loss of information over time

Absentmindedness

When inattention leads to inability to recall information

Blocking

Inability to retrieve an item in memory because another memory interferes and blocks retrieval

Misattribution

Recalling a piece of information but incorrectly recalling the source

Suggestibility

When a recollection is changed because outside information suggests the initial recollection is incorrect

Bias

When a person's state of mind causes the differential recall of information

Persistence

The unwanted recall of distressing memories

Jost's law

For memories of similar strength, the older memory will decay more slowly than the newer memory

Three-factor theory of forgetting (McGeoch)

Theory that forgetting results from three processes:

1. Response competition: when a query results in more than one item being retrieved such that the correct response is not indicated
2. Altered stimulus conditions: when context at retrieval does not match context at encoding and thus appropriate retrieval cues are unavailable
3. Set (mental set): when retrieval fails because context causes individuals to recall the wrong set of information

Paired-associate paradigm

A research paradigm in which participants study word pairs and then are given new word pairs which may or may not partially overlap with old pairs

Promiscuous coding

Encoding of all events an organism experiences, necessary as there is no way to know ahead of time which experiences will be useful in the future

Two components of explicit memory

1. Contents of the memory, stored in the neocortex

2. Spatial-contextual information within which the memory was encoded, stored in the hippocampus

Neurogenesis-dependent decay

Forgetting that is the result of impaired pattern completion (reactivation of neural activity from encoding) due to integration of new neurons in the hippocampus

Molecular decay

1. Long-term depotentiation of a neuron as NMDA receptors occasionally let calcium in and depolarize the neuron, causing AMPA receptors to degrade
2. Absorption of AMPA receptors into the neuron when a memory is not reactivated as the protein PMK-zeta is not produced

Forgetting in the neocortex

• Familiarity-based memory (associated with the neocortex) is susceptible to forgetting, whereas recollection-based memory (associated with the hippocampus) is not

• Individuals with hippocampal damage who rely on the neocortex for memory are highly susceptible to interference

Neurogenic hypothesis of infantile amnesia

Infantile amnesia occurs because the rate of neurogenesis in the hippocampus is very high during the early years of life, and memory becomes more stable as neurogenesis slows down

Retrieval-induced forgetting

Forgetting that occurs due to selective retrieval of only some similar items

Competition-induced interference

Theory that retrieval-induced forgetting occurs because having to inhibit similar items in order to retrieve one item results in later forgetting of the inhibited item

Context explanation of retrieval-induced forgetting

Theory that retrieval-induced forgetting occurs because the type of cognitive activities taking place produce mental context; studying words produces a different mental context than retrieving words, so during a test phase, only words that received retrieval practice match the mental context and are retrieved

Incidental forgetting

Forgetting without the intention to forget

Motivated forgetting

Actively trying to diminish the accessibility of information in memory

Evidence for the dual-process model of directed forgetting

• Temporary inhibition of L1 items would not explain the benefit of forgetting for L2 items

• Power (neurons in the same area firing together) predicts the benefit of forgetting, whereas phase (different brain regions firing together) predicts cost of forgetting, suggesting a dual-process model

Four ways of achieving intentional forgetting

1. Encoding suppression: processes that make encoding less likely to be successful

2. Changing context: avoiding reminders of the event, to avoid cues that trigger the memory and prevents strengthening of the memory via activation

3. Retrieval suppression: stopping an encoded memory from entering conscious awareness

4. Thought substitution: intentionally thinking about other things when the thing you want to forget comes to mind (best if the substitution is radically different)