Memory and state dependence Flashcards
Ebbinghaus (1850-1909)
Conducted the first investigations on memory. Used himself as a participant and tested himself over and over using nonsense syllables to test how memory works. He was mainly interested in associations. How can one event retrieve another event?
He would look to see how many attempts it took to memorize and see how much “savings” of the memories that he had. He was the first one to produce a forgetting curve.
Excitatory conditioning
Rats were exposed to higher intensities of the US to suppress, which was linked to higher suppression of their licking behaviour. Irrespective of the US intensity, hardly any forgetting was observed even after 60 days. Results were consistent both one day and 60 days later (Hendersen 1985).
What is a summation test?
Take an excitatory stimulus (that elicits fear) and then expose the animal to an inhibitor. This is then compared to the excitatory cue alone.
Inhibitory conditioning
You can train a stimulus to become an inhibitor, when it signals the absence of something, usually an aversive outcome. After a period of time, the inhibitor then no longer suppresses the fear.
How can performance in memory tasks be improved?
By providing a retrieval cue.
Give an example of the impact of retrieval cues on memory.
Gordon et al (1979): A CS was paired with a shock. The animal was tested three days later.
Without reminder condition: There was very little evidence of retention when tested 72 hours later or immediately after.
With reminder condition: A day before the test, they would present a reminder by giving a brief exposure to the CS and apparatus. Performance then improved to a high level of fear expression.
Deweer & Sara (1984)
Krechevsky maze. The number of errors a rat made in a maze was counted. It was found that they exhibited rapid learning. However, they forgot this learning when tested again 25 days later.
However, memory performance was restored when given a 90-second reminder prior to the test. As training progressed, errors reduced.
Presented with reminders of extra-maze contexts for varying time periods.
10 second reminder - no change
30 and 90 seconds seem to be most effective in aiding the retrieval of memory. 90 seconds of reminder lead to the same performance as the end of training.
300 seconds: Too much exposure to the reminder would start to hinder performance later on. Extinguished the CS without US.
Can memories be forgotten?
Unlikely. Although we may see a low performance when we do a test, this does not mean that the information has disappeared from the brain.
May not suggest that the memories are gone, but the failure that we see may be retrieval failure rather than a storage failure. We simply haven’t used the right retrieval cues.
What are the theories of forgetting?
Trace delay theory and interference theory
What is the trace delay theory?
It is a family of theories. Information storage is reflected by physical changes in the brain at the level of the synapse. In the absence of rehearsal, this connection becomes weaker with the passage of time. If a trace weakens, it simply reflects that the memory is no longer there. It assumes that forgetting is equal to memory erasure.
What is one downside of the trace delay theory?
It does not explain the effect of reminders.
What is the interference theory?
The interference theory posits that all information is stored in the brain through associations. Recall is guided by cues or stimuli to which memory items are associated. Multiple items may become associated with the same cue over time. Other items may be learned before (proactive) or after (retroactive) the target response, and this interference should be a function of similarity.
Forgetting is thus not a matter of the memory disappearing, but rather, a failure to “find” it.
What are the theoretical implications of experimental studies on memory?
If trace delay is the cause of forgetting, memories can last a lot longer than previously believed. Reminders indicate that memories can be forgotten without having decayed. Temporary retrieval problems point to interference as a cause of forgetting. Associative learning can serve to explain reminders.
What is context?
A diffused set of stimuli (as compared to a discrete set of stimuli)
What is a crossover design?
If one group was trained on land, their memory would be tested underwater. The same conditions that were established during training should be maintained.
