Memory and State dependence

Question 1

Forgetting curve

Answer 1

Ebbinghaus
Serial learning task
Himself as participant
Forgetting initially rapid then levels off

Question 2

Excitatory conditioning

Answer 2

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

Question 3

Inhibitory conditioning

Answer 3

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

Question 4

Forgetting can be reduced by a reminder

Answer 4

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

Question 5

Reminder duration

Answer 5

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

Question 6

Trace decay theory

Answer 6

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

Question 7

Interference theory

Answer 7

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

Question 8

Theoretical implications of experimental observations

Answer 8

• 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

Question 9

Encoding specificity

Answer 9

• 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)

Question 10

Internal states - Mood

Answer 10

• 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

Question 11

Classic experiment: Overton (1964)

Answer 11

• 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

Question 12

State dependent extinction (Bouton et al., 1990)

Answer 12

• 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

Question 13

Goodwin et al. (1969)

Answer 13

(non-alcoholic) subjects can’t remember, when sober, what happened when drunk. May remember when next drunk

Question 14

Eich et al. (1975)

Answer 14

marijuana produced state-dependent effect when no (external) cues to recall were available

Question 15

Hurst et al. (1969)

Answer 15

amphetamine ineffective (but paired associate task!)

Question 16

Bustamante et al. (1970)

Answer 16

amphetamine did result in state-dependency (free recall task, drawing geometric shapes)

Question 17

State-dependency unreliable? Overshadowing effects

Answer 17

• 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

Question 18

Parker et al (2001)

Answer 18

Smell experiment
Mean recall higher when lemon matched with lemon and lavender matched with lavender compared to opposites matched

Question 19

What is extinction learning

Answer 19

gradual decrease in response to a conditioned stimulus that occurs when the stimulus is presented without reinforcement

Question 20

Ramanathan et al., 2018

Answer 20

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