Human Memory III

Memory For Complex EventsOur memory serves us quite well in many instances. It isn’t hard to remember things that happened earlier today or ten years ago.

However, there are times when our memory goes awry:- Drawing a blank when you can’t remember the name of

the person approaching you at a party (e.g.., “Oh no. That’s the guy from PR)

- Remembering something, but without much confidence in the recall (e.g., “I think his name is ‘Bill’)

- A recalled memory turns out to be incorrect (e.g., The Magic Sword)

- Remembering events that didn’t even occur

An Hypothesis For Memory Errors

Memory errors can occur at any stage in the process, from initial exposure to recall. In all cases, however, the errors involve connections and that those connections facilitate retrieval.

As you make more and more connections for a new episode (e.g., going to an antique show), you end up with a web of connections representing the episode. There are such webs for many other episodes as well, yet there are no distinct separations between one episode and any other.

An Hypothesis For Memory Errors (con’t)

The density of connections between elements within one episode are greater than the density of connections between episodes.

How, then, do we keep pieces of one episode together and distinguishable from other episodes?

Yet, as you add connections between elements from different episodes, you are increasing the density of connections between episodes and possibly leading to transplant or intrusion errors – errors in which other knowledge intrudes into the remembered event.

Understanding: A Double-Edged SwordForming connections is a double-edged sword: many connections facilitate retrieval but also increase the difficulty in keeping separate the actual episode and other “associated material.” Furthermore, we noted that “understanding” facilitates the formation of connections. For example:“The procedure is actually quite simple. First you arrange items into different groups. Of course one pile may be sufficient depending on how much there is to do. If you have to go somewhere else due to lack of facilities that is the next step; otherwise you are pretty well set. It is important not to overdo things. That is, it is better to do too few things at once than too many. In the short run, this may not seem important but complications can easily arise. A mistake can be expensive as well. At first, the whole procedure will seem complicated. Soon, however, it will become just another facet of life. It is difficult to foresee any end to the necessity for this task in the immediate future, but then, one never can tell. After the procedure is completed one arranges the materials into different groups again. Then they can be put into their appropriate places. Eventually they will be used once more and the whole cycle will then have to be repeated. However, that is part of life.”

A Double-Edged Sword (con’t)Additional connections resulting from “understanding” can cause intrusion errors. Consider the following:

Other subjects read a prologue before the above passage:

“Nancy woke up feeling sick again and she wondered if she really were pregnant. How would she tell the professor she had been seeing? And the money was another problem.”

“Nancy arrived at the cocktail party. She looked around the room to see who was there. She went to talk with her professor. She felt she had to talk to him but was a little nervous about just what to say. A group of people started to play charades. Nancy went over and had some refreshments. The hors d’oeuvres were good but she wasn’t interested in talking to the rest of the people at the party. After a while she decided she’d had enough and left the party.”

A Double-Edged Sword (con’t)Those who read the prologue had many more “intrusions” during recall.

It should be noted, however, that those who read the prologue also recalled more of the actual story as well.

The Deese-Roediger-McDermott (DRM) procedure demonstrates how easy it is to induce intrusions with simple word lists. Let’s try a quick experiment:

Schematic Knowledge

In everyday situations we rely on large knowledge structures called schemata (singular: schema). Schemata help us to:

• know what is likely to occur in a given situation• easily incorporate new information• recall by reconstructing “missing” pieces of information at time or recall

While schematic knowledge helps, it can also hurt our initial perception and subsequent recall of events. That is, they help “fill in the gaps” during our current perceptions and at recall.

In that way, our current experience seems more “typical” than it might actually be and the past seems more “regular” than it actually was.

War of the GhostsOne night two young men from Egulac went down to the river to hunt seals and while they were there it became foggy and calm. Then they heard war-cries, and they thought: "Maybe this is a war-party". They escaped to the shore, and hid behind a log. Now canoes came up, and they heard the noise of paddles, and saw one canoe coming up to them. There were five men in the canoe, and they said:

"What do you think? We wish to take you along. We are going up the river to make war on the people."

One of the young men said, "I have no arrows."

"Arrows are in the canoe," they said.

"I will not go along. I might be killed. My relatives do not know where I have gone. But you," he said, turning to the other, "may go with them."

So one of the young men went, but the other returned home.

And the warriors went on up the river to a town on the other side of Kalama. The people came down to the water and they began to fight, and many were killed. But presently the young man heard one of the warriors say, "Quick, let us go home: that Indian has been hit." Now he thought: "Oh, they are ghosts." He did not feel sick, but they said he had been shot.

So the canoes went back to Egulac and the young man went ashore to his house and made a fire. And he told everybody and said: "Behold I accompanied the ghosts, and we went to fight. Many of our fellows were killed, and many of those who attacked us were killed. They said I was hit, and I did not feel sick."

He told it all, and then he became quiet. When the sun rose he fell down. Something black came out of his mouth. His face became contorted. The people jumped up and cried.

He was dead.

War of the Ghosts (con’t)Subjects consistently made similar errors and recalled it as a more “normal” story that fit their cultural schema.

The influence of schemata has been demonstrated in the laboratory as well. Subjects “remembered” books and other typical office items that were not actually present.

Implanting False MemoriesSchematic knowledge, while benefiting integration and recall, also adds or subtracts bits to “regularize” the memory at recall.

It is possible to artificially “implant” some “bits” to one’s memory without the individual’s awareness that has happened?

Loftus (and others) have demonstrated how easy it is to alter one’s memory simply by suggesting some misleading information about the event.

Such errors in recall are referred to as the misinformation effect. Not only can misinformation produce minor changes in recall, but it can actually be used to implant memories of entire episodes that never occurred!

Implanting False Memories (con’t)It is easier to implant false memories when:

1. the memory is “plausible”

2. the memory is repeated

3. the subject is encouraged to “imagine” how the memory happened – call “imagination inflation”

4. some people are more susceptible to memory implantation

Avoiding Memory Errors?Given the phenomenon of the misinformation effect, we must question just how much can we trust our own memories.

Overall, our memories can be trusted to give us rather complete and correct recollections.

However, we have seen that “intrusions” contribute to memory errors, but retention interval is also a crucial factor. As the interval increases, we forget more and more and need to rely on reconstruction at retrieval to fill the missing gaps. Over time, the reconstructions begin to become indistinguishable from what really occurred... we have a more difficult time with source monitoring.

Avoiding Memory Errors? (con’t)There are several possibilities why the passage of time is so important when it comes to forgetting:

Decay Theory - the theory that we forget material simply as a function of the passage of time.

Neural data has shown a power function in the decrease of long-term potentiation (LTP) for forgetting, suggesting the strength of the memory trace weakens over time as a result of a weakening of the synaptic strength.

Avoiding Memory Errors? (con’t)Interference Effects - learning new material negatively impacting the recall of previously learned material.

Interference effects, then, may be: 1) the result of a form of retrieval failure; 2) that new information may become interwoven with older information; or 3) that the new information may literally destroy old information (like deleting an old phone number in your address book when you have a new number – destructive updating).

Control Group Experimental Group------------------------------------------------------------------------Learn A - B (DAX - BIV) Learn A - B (DAX - BIV)Learn C - D (CIF - JOL) Learn A - D (DAX - JOL)------------------------------------------------------------------------Recall A - B Recall A - B

Avoiding Memory Errors? (con’t)Retrieval Failure - with increased retention intervals there is a greater chance that our physical or mental perspectives at retrieval will be different than at time of study and, therefore, a greater chance of retrieval failure.

In summary, each of the above contributes to forgetting with increased retention intervals.

Undoing Forgetting?There are some who argue that information in LTM is never lost. If so, are there ways that forgetting can be reversed?

• Hypnosis and drugs (e.g., sodium amytal) have been used, but have met without success.

• Brain stimulation has also been used, but the results are inconclusive.

• Providing an array of “cues” can, in some cases, result in the retrieval of “forgotten” memories.

Detecting Forgetting?If we cannot undo forgetting, or prevent forgetting from happening in the first place, can we detect memory errors when they occur?

It seems we are more confident in some memories (e.g., “I’m certain I told you a UCS elicits a UCR and not a CR”) than in others (e.g., “I think he said to meet at 7:00, but I’m not sure”).

As it turns out, our sense of “confidence” in our recall is not a good measure of how trustworthy the memories are.

Other attempts to find a reliable way to distinguish between accurate memories and false memories have also met with little success. It seems that once a memory is part of our LTM, we cannot distinguish between accurate and false memories.

Autobiographical MemoryGiven that our memories make us who we are, there is considerable interest in the factors that affect autobiographical memory (also known as “episodic” memory).

We will explore several questions related to this are of memory:

How does “involvement” in the event (versus passive “watching”) influence recall?

What role do “emotions” play in recall?

How does delay in recall affect memory?

Participant vs SpectatorWe all tend to remember information that is relevant to ourselves better than information that is not self-relevant. That is called the self-reference effect.

In part, that advantage is the result of our self-schema.

However, that schema is susceptible to the same memory failings as are other schemas. While resulting in many accurate memories, it will fill in missing "gaps" and "regularize" the past.

Our self-schema will also provide us with a more positive image of ourselves in he past.

Memory and Emotion

In addition to promoting consolidation, the presence of emotions seems to focus our attention on more important aspects of the event.

We also tend to “mull” over emotional events more and, thus, have more opportunity to rehearse the event.

Have you ever cried as a wedding couple said their vows? Did you cheer when your team won the championship game? Were you seething with rage when they cancelled the new "Charlie's Angels" TV show?

Flashbulb MemoriesParticularly emotional events sometimes “burn” themselves into our memories

Such memories are called “flashbulb” memories and can be recalled in great detail.

However, it seems that true flashbulb memories are more likely to occur when the event has some personal consequence for the individual.

Do you have any flashbulb memories? How are they different from other memories?

Traumatic EventsUnfortunately, there are some events that are even more emotion-laden than those resulting in flashbulb memories… traumatic events that individuals have experienced.

Emotional events are connected with increased activity of the amygdala, which promotes memory consolidation. The amygdala has also been implicated in memory retrieval of the event and the emotion associated with the event.

In general, traumatic events leave the individual with vivid, long-lasting memories of the event.

Traumatic Events (con’t)In some cases, however, the individual may have little or no recall of the traumatic event. How is this possible?

1. Childhood amnesia

2. Disruption of consolidation

3. Repression

Traumatic Events (con’t)Many, however, are skeptical about repression:

Many traumatic events are remembered.

Some “repressed” memories have always been available, but the individual was just unwilling to discuss it.

Repressed memories may simply be a function of retrieval failure, but given the appropriate cue, the memory is recalled.

Some “recovered memories” may be false, resulting from “implanting” a memory by the therapist.

Real Long-Term RememberingIt is surprising just how long ago an event occurred or some information learned, yet we are still able to recall the event or information.

1. Material is very well-learned initially

2. Continued learning the same area

3. Rehearsal – “use it, or lose it”

In general, most of the forgetting for an event or information happens within the first 3-4 years, but then the memory is fairly stable thereafter… what is sometimes referred to as permastore.

Permastore is more likely to be achieved when: