Since the 1960’s, most researchers hold the view that information is not lost from long-term memory (barring organic causes). Instead, they view forgetting primarily as a problem of retrieval. Furthermore, it has been shown that information can be more easily retrieved when the proper retrieval cues are used. Some evidence for this lies in what has been called TOT (the tip of the tongue phenomenon). Of course, this refers to the times when somebody knows something, and knows that they know it, yet can not produce it even though they may know certain information about it (e.g. rhymes with “cat”, starts with “m”—it must be “Matt”).

Tulving and Pearlstone (1966, in Willingham, 2001) argued that TOT is a common occurrence, and furthermore that it is a fundamental aspect of memory. To prove this, they gave subjects lists of four items each in 12 categories (e.g. crimes, professions, and animals). Each item was preceded by the category name, but subjects were told they only had to remember the items themselves. At this point, all subjects had been treated the same, so it can be assumed they acquired and retained the same information. Next, one group of subjects was asked to give the items on the list using free recall. The other group was cued with the category name and asked to recall the items in that category. The free recall group remembered 40% vs. 62% recall in the cued recall group.

From this we can conclude that category cues increased recall and that information is in memory, but is not always accessible. Furthermore, information recalled underestimates the amount of information learned. We can also conclude that in the absence of appropriate cues, “forgetting” is most likely an inability to recall and not a failure of storage.

Now that we have established the importance of retrieval cues in recall, we can look at the various factors and types of cues that are effective and appropriate. Appropriate retrieval cues typically are similar to, contiguous to or associated in some way with the information we wish to retrieve.

We can group items according to similar characteristics, and items with those characteristics can be brought into mind more easily. For example, we could make a list of things that are red, in which case the color red would be our retrieval cue. We can also group things according to their contiguity in time and space. If we think of the word “river” we are able to come up with certain characteristics of rivers and things associated with rivers (e.g. fish, water, flow, bank). From these similarities we can construct what is called a Network Model that shows relationships between objects based on similarities, contiguity and association. A sample Network Model is provided below.

A Possible Network Model


    /\    higher levels of abstraction (bigger chunks)
     |
     |                Things
     |               /      \
     |      buildings        animals
     |     /         \      /       \
     |  houses   museums   cats     dogs
     |
     |
    \/    lower levels of abstraction (smaller chunks)

Halpern (1986, in Willingham, 2001) found that hierarchical organization is indeed an efficient way of organizing and remembering information. Subjects were given a chart to memorize that had 54 well-known song titles. Some subjects got a chart with the songs organized into categories, while other subjects got a chart that was not. Recall tests on the subjects found that those who got a categorized chart recalled far more than those whose chart was not in categories did. It is thought that the category name itself served as an effective retrieval cue in the minds of the subjects.

Tulving (1974, in Willingham, 2001) identified another variable that affects cued recall and called it the Encoding Specificity Principle. Basically, it states that salient pieces of information attended to at the time of encoding serve as powerful cues for later recall. This has led to theories about context dependent and state dependent memory. Bransford and Franks (1977, in Willingham, 2001) performed an experiment that was later interpreted by Morris et al (in Willingham, 2001) as evidence that similar processes at time of encoding will affect later retrieval. During encoding, participants were given either rhyming cues or semantic cues about a word. They were later given a cued recall test using either the rhyming cue or the semantic cue. The results showed that rhyming cues were more effective for recall of words that were encoded using a rhyme than semantically, and semantic cues were more effective for words that were encoded using a semantic task than the rhyming task.

Another experiment lending support to the Encoding Specificity Principle was conducted by Montyla (1986, in Willingham, 2001). Subjects were given a list of 500 nouns and were told to write either one or three word(s) describing the noun. Later the subjects were asked to recall items from the list. Some subjects were given their own descriptions of the noun and others were given other people’s descriptions of the noun. The results indicated little difference between subjects who got their own cues vs. subjects who got someone else’s cues. There were, however, differences in recall for the number of cues provided. When 3 descriptive words were provided, accuracy was around 60-90%. This number decreased to 8-50% when only one cue was given.

Another way to cue retrieval is called priming. Priming is the process of presenting an event, episode, stimulus, etc. that prepares a system for functioning. One study investigating the priming effect was conducted by Meyer and Schvaneveldt (1971, in Willingham, 2001). Subjects were shown two strings of letters and were asked to press one button if both were words and another button if one was not a word. They found that reaction time was shorter if the two words were semantically related than if the words were not semantically related. Reaction time was longest when one of the strings was not a word.

In summary, the cues that are most effective in probing our memory are those that are similar according to some feature, cues that use the same process that was used during encoding, cues that are contiguous in time and space, cues that are semantically related, and cues that are otherwise associated in conceptual hierarchies.


References

Willingham, D.B. (2001). Cognition: The thinking animal. Upper Saddle River, NJ: Prentice Hall.

Why you must not ignore retrieval processes when thinking about memory:

If one only thinks of memory in terms of memory traces or engrams or objects, and only thinks of memory tests as varying in sensitivity to the strength or firmness or size of these memories, then a major part of the story is missed. The information that is retrieved, or expressed, during a memory test can vary depending on the technique used to retrieve the information.

“The key process of memory is retrieval.”
-Endel Tulving

Memory researchers long assumed that the level of processing of a stimulus has a systematic effect on how the memory of the stimulus is later recalled. They believed that intermediate processing will always result in stronger memories than shallow processing, and deep processing will always result in stronger memories than intermediate processing, regardless of retrieval conditions. However, these long-held assumptions about memory are nullified when the retrieval condition is manipulated between a standard recognition test and a word identification test involving a briefly (50 ms) flashed cue. Although encoding conditions remained the same, the method of retrieval became the “key process” in this experiment.

Another common assumption about memory overturned by retrieval manipulation is the theory that recognition is always more accurate and fruitful than recall. However, research by Tulving and Thompson in 1973 showed that even the recognition of self-generated words could be worse than recall. To do so requires controlling the retrieval conditions. When the retrieval conditions match the encoding conditions that surrounded the self-generation procedure, the counter-intuitive failure of recognition of self-generated words presents itself.

State dependent conditions during retrieval and encoding can effect a memory test. If you learn material while drinking alcohol, you will benefit from being in a similar state during retrieval. The same applies for various types of drug intoxication. Also, if you learned words while they were blurry, you will benefit in a recognition test if the test words are blurry, too. There are a lot of fun state dependent retrieval effects.

Retrieval conditions can also be a matter of life and death. Even in situations of police lineups, where hits and false alarms can have large consequences and encoding conditions can be from powerful, highly emotional situations, retrieval can be the decisive factor. Just by warning a viewer of a lineup that the culprit might not be present in the display can decrease mistakes by 40%. This sort of cue is only a change in the retrieval condition. Limiting the viewer to one potential culprit at a time by using a sequential lineup can cut mistaken identifications in half. Again, this manipulation only involves the retrieval condition.

As Tulving proposed, retrieval conditions do in fact play a “key” role in the outcome of various forms of memory tasks, and many times regardless of encoding conditions.

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