Memory and State dependence Flashcards
Forgetting curve
Ebbinghaus
Serial learning task
Himself as participant
Forgetting initially rapid then levels off
Excitatory conditioning
Conditioned suppression of licking procedure
Irrespective of US intensity, hardly any forgetting after 60 days
So, memory traces can last as long as 60 days
Remember tone is paired with shock
Hendersen, 1985
Inhibitory conditioning
Fear conditioning procedures with shock US
So, in a more complex learning situation, some forgetting seen within 35 days
Compared to just excitatory CS with excitatory and inhibitor
Inhibitor suppresses fear after 1 day, no longer after 35 days
Hendersen, 1978
Forgetting can be reduced by a reminder
Avoidance learning procedure
Memory performance improved by a reminder (apparatus and CS exposure) 24 hr or 10 min prior to test
Very little retention 72 hours later or without reminder
Gordon et al., 1979
Reminder duration
Krechevsky maze (Deweer & Sara, 1984)
Rapid learning seen by decrease in number of errors
Forgetting when tested 25 days leater
Reminder of (secs) 10,30,90 or 300
Memory performances restored by a reminder of 90 secs prior to test
300s not as good as 90s, too long exposure
Trace decay theory
Information storage is reflected by physical changes in the brain and in the absence of rehearsal these memory traces become weaker with the passage of time
if a trace “disappears” (or weakens), the memory is not there
Fails to explain the effect of reminders
- Describes well the forgetting curve
- It is simple
Interference theory
McGeoch 1932
Argued that human memory is fundamentally associative
Recall is guided by cues or stimuli to which items in memory are associated
Multiple items may become associated with the same cue
Other responses may have been learned before or after the target response (proactive and retroactive interference
Theoretical implications of experimental observations
- Memories can last a lot longer than you might think if trace decay were the cause of forgetting
- The fact that reminders can jog memories suggests that memories can be forgotten without necessarily having decayed
- Temporary retrieval problems point to the importance of interference as a cause of forgetting
- Associative learning can explain how reminders work
Encoding specificity
- Tulving & Thomson (1973)
- Encoding in context provides memory triggers
- Category names (e.g., animal) for word lists (e.g., cow, rat, etc.)
- Effective cues enable the retrieval of items that would not be retrieved under non-cued recall conditions (Tulving & Pearlstone, 1966)
Internal states - Mood
- Bower and colleagues used hypnosis to induce either happy (H) or sad (S) moods in their participants.
- Participants learned 2 lists one following H induction and one following S induction. They were tested on both lists after either H or S induction.
Better when learnt in same state
Classic experiment: Overton (1964)
- Rats trained to escape from unavoidable shock in a T-maze
- Sodium pentobarbital produced ‘dissociated learning’ in rats
- Seen when performance of tasks learned in the drug state does not transfer to the non-drug state
- But learning can be reactivated if the drug is re-instated
State dependent extinction (Bouton et al., 1990)
- Context fear conditioning preparation (measured freezing)
- Chlordiazepoxide (a benzodiazepine) was administered during extinction learning, as it happens during treatment of anxiety
- Rats were conditioned and then experienced extinction (or not) drugged.
- Rats were tested both sober and with the drug (on separate days)
- Effect of drugs much stronger with extinction
Goodwin et al. (1969)
(non-alcoholic) subjects can’t remember, when sober, what happened when drunk. May remember when next drunk
Eich et al. (1975)
marijuana produced state-dependent effect when no (external) cues to recall were available
Hurst et al. (1969)
amphetamine ineffective (but paired associate task!)
Bustamante et al. (1970)
amphetamine did result in state-dependency (free recall task, drawing geometric shapes)
State-dependency unreliable? Overshadowing effects
- Eich (1980)
- 88% studies showing evidence for state-dependent effects used free recall tasks
- 90% studies that did not show state dependency used cued recall or recognition tests (familiar?)
- Suggests internal state more important cue in the absence of ‘observable’ retrieval cues
- State-dependent effects consistent and reproducible only when contextual cues are not overshadowed by more explicit reminders
CRITIQUES
Parker et al (2001)
Smell experiment
Mean recall higher when lemon matched with lemon and lavender matched with lavender compared to opposites matched
What is extinction learning
gradual decrease in response to a conditioned stimulus that occurs when the stimulus is presented without reinforcement
Ramanathan et al., 2018
State-dependent due to intracerebral inactivation
Nucleus reuniens (RE) is a midline thalamic nucleus that interconnects the mPFC with the hippocampus
Context fear conditioning in rats
Train in Context A, and tested in Contexts A (target) and B (generalization)
State dependent learning activated by certain brain region
