Recall (memory)
Contents |
Theories
Two-stage theory
The two-stage theory states that the process of recall begins with a search and retrieval process, and then a decision or recognition process where the correct information is chosen from what has been retrieved. In this theory, recognition only involves the latter of these two stages, or processes, and this is thought to account for the superiority of the recognition process over recall. Recognition only involves one process in which error or failure may occur, while recall involves two . However, recall has been found to be superior to recognition in some cases, such as a failure to recognize words that can later be recalled.
Encoding specificity
The theory of encoding specificity finds similarities between the process of recognition and that of recall. The encoding specificity principle states that memory utilizes information from the memory trace, or the situation in which it was learned, and from the environment in which it is retrieved. Encoding specificity helps to take into account context cues because of its focus on the retrieval environment, and it also accounts for the fact recognition may not always be superior to recall.
History
Philosophical questions regarding how people acquire knowledge about their world spurred the study of memory and learning. Recall is a major part of the study of memory and often comes into play in all research. For this reason, the main studies on memory in general will also provide a history to the study of recall.
Beginning with Hermann Ebbinghaus in 1885, the study of memory has continued to be a popular topic among researchers. Ebbinghaus created nonsense syllables, combinations of letters that do not follow grammatical rules and have no meaning, to test his own memory. He would memorize a list of nonsense syllables and then test his recall of that list over varying time periods. He discovered that memory loss occurred rapidly over the first few hours or days, but showed a more steady, gradual decline over subsequent days, weeks, and months. Furthermore, Ebbinghaus discovered that multiple learning, over-learning, and spacing study times increased retention of information. Ebbinghaus’ research influenced much of the research conducted on memory and recall throughout the twentieth century.
Frederic Bartlett a prominent researcher in the field of memory during the mid-twentieth century. He was a British experimental psychologist who focused on the mistakes people made when recalling new information. One of his well known works was Remembering: A Study in Experimental and Social Psychology, which he published in 1932. He is well known for his use of North American Native folk tales, including The War of the Ghosts. He would provide participants in his study with an excerpt from a story and then asked them to recall it as accurately as they could. Retention intervals would vary from directly after reading the story to days later. Bartlett found that people strive for meaning, by attempting to understand the overall meaning of the story. Since the folk tale included supernatural elements, people would rationalize them to make them fit better with their own culture. Ultimately, Bartlett argued that the mistakes that the participants made could be attributed to schematic intrusions. Their current sets of knowledge intruded on them accurately recalling the folk tale.
In the 1950s there was a change in the overall study of memory that has come to be known as the cognitive revolution. This included new theories on how to view memory, often likening it to a computer processing model. Two important books influenced the revolution: Plans and Structures of Behavior by George Miller, Eugene Galanter, and Karl H. Pribram in 1960 and Cognitive Psychology by Ulric Neisser in 1967. Both provided arguments for an information-processing view of the human mind. Allen Newell and Herbert Simon constructed computer programs that simulated the thought processes people go through when solving different kinds of problems.
In the 1960s, interest in short-term memory (STM) increased. Before the 1960s, there was very little research that studied the workings of short-term memory and rapid memory loss. Lloyd and Margaret Peterson observed that when people are given a short list of words or letters and then are distracted and occupied with another task for few seconds, their memory for the list is greatly decreased. Atkinson and Shiffrin (1973) created the short term memory model, which became the popular model for studying short term memory.
The next major development in the study of memory recall was Endel Tulving’s proposition of two kinds of memory: episodic and semantic. Tulving described episodic memory as a memory about a specific event that occurred at a particular time and place, for example what you got for your 10th birthday. Semantic memories are abstract words, concepts, and rules stored in long-term memory. Furthermore, Endel Tulving devised the encoding specificity principle in 1983, which explains the importance of the relation between the encoding of information and then recalling that information. To explain further, the encoding specificity principle means that a person is more likely to recall information if the recall cues match or are similar to the encoding cues.
The 1960s also saw a development in the study of visual imagery and how it is recalled. This research was led by Allan Paivio, who found that the more image-arousing a word was the more likely it would be recalled in either free recall or paired associates.
There has been a considerable amount of research into the workings of memory, and specifically recall since the 1980s. The previously mentioned research was developed and improved upon, and new research was and still is being conducted.
Types
Free recall
Free recall describes the process in which a person is given a list of items to remember and then is tested by being asked to recall them in any order. Free recall often displays evidence of primacy and recency effects. Primacy effects are displayed when the person recalls items presented at the beginning of the list earlier and more often. The recency effect is when the person recalls items presented at the end of the list earlier and more often.
Cued recall
Cued Recall refers to the process in which a person is given a list of items to remember and is then tested with the use of cues. Cues act as guides to what the person is supposed to remember. In contrast to free recall, the person is prompted to remember a certain item on the list or remember the list in a certain order. Cued recall also plays into free recall because when cues are provided to a person they remember items on the list that they did not originally recall without a cue. This was explained in research by Tulving: when he gave participants associative cues to items that they did not originally recall and thought to be lost to memory, the participant was able to recall the item.
Cued recall can also take the form of stimulus-response recall. This occurs when words, pictures, and numbers are presented together in a pair with the intent of creating associations between the two items. When one item of the pair is presented to a person it is expected to cue the recall of the second item in the pair.
Serial recall
Serial recall refers to our ability to recall items or events in the order in which they occurred . The ability of humans to store items in memory and recall them is important to the use of language. Imagine recalling the different parts of a sentence, but in the wrong order. The ability to recall in serial order has been found not only in humans, but in a number of non-human primate species and some non-primates . Imagine mixing up the order of phonemes, or meaningful units of sound, in a word so that “slight” becomes “style." Serial-order also helps us remember the order of events in our lives, our autobiographical memories. Our memory of our past appears to exist on a continuum on which more recent events are more easily remembered in order .
Serial recall in long-term memory (LTM) differs from serial recall in short-term memory (STM). To store a sequence in LTM, the sequence is repeated over time until it is represented in memory as a whole, rather than as a series of items. In this way, there is no need to remember the relationships between the items and their original positions. In STM, immediate serial recall (ISR) has been thought to result from one of two mechanisms. The first refers to ISR as a result of associations between the items and their positions in a sequence, while the second refers to associations between items. These associations between items are referred to as chaining, and according to research it is an unlikely mechanism. Position-item relationships do not account for recency and primacy effects, or the phonological similarity effect. The Primacy Model moves away from these two assumptions, suggesting that ISR results from a gradient of activation levels where each item has a particular level of activation that corresponds to its position.
Seven different effects are generally seen in serial recall studies with humans:
- 1. List length effect
- Performance for serial recall decreases as the length of the list or sequence increases.
- 2. Primacy and recency effects
- Primacy effects refer to better recall of items earlier in the sequence, while recency effects refer to better recall of the last few items. Recency effects are seen more with auditory stimuli rather than verbal stimuli.
- 3. Transposition gradients
- Transposition gradients refer to the fact that recall tends to be better for item identity rather than the order of items in a sequence. Basically, subjects tend to remember the correct items in the wrong order.
- 4. Item confusion errors
- When an item is incorrectly recalled, there is a tendency to respond with an item that resembles the original item in that position. When tested with verbal stimuli, the mistakes tended to be phonological (e.g. DOG instead of FOG), while spatial stimuli tended to have spatial similarity (e.g. spatial proximity).
- 5. Repetition errors
- These occur during the recall of a sequence when an item from an earlier position in the sequence is given again in another position. This effect is fairly rare in humans.
- 6. Fill-in effects
- If an item is recalled incorrectly at an earlier position than its original place, there is a tendency for the next item recalled to be the item that was displaced by this error. For example, if the sequence is 'LMNOP' and recall began 'LMO', then the next item is likely to be ‘N’.
- 7. Protrusion effects
- These occur when an item from a previous trial is recalled in a current trial. This item is likely to be recalled at its position from the original trial.
Neuroanatomy
The anterior cingulate cortex, globus pallidus, thalamus, and cerebellum show higher activation during recall than during recognition which suggests that these components of the cerebello-frontal pathway play a role in recall processes that they do not in recognition. Although recall and recognition are considered separate processes, it should be noted that they are both most likely constitute components of distributed networks of brain regions.
According to neuroimaging data, PET studies on recall and recognition have consistently found increases in regional cerebral blood flow (RCBF) in the following six brain regions: (1) the prefrontal cortex, particularly on the right hemisphere; (2) the hippocampal and parahippocampal regions of the medial temporal lobe; (3) the anterior cingulate cortex; (4) the posterior midline area that includes posterior cingulate, retrosplenial (see retrosplenial region), precuneus, and cuneus regions; (5) the inferior parietal cortex, especially on the right hemisphere; and (6) the cerebellum, particularly on the left.
The specific role of each of the six main regions in episodic retrieval is still unclear, but some ideas have been suggested. The right prefrontal cortex has been related to retrieval attempt; the medial temporal lobes to conscious recollection ; the anterior cingulate to response selection ; the posterior midline region to imagery ; the inferior parietal to awareness of space; and the cerebellum to self-initiated retrieval .
In recent research, a group of subjects was faced with remembering a list of items and then measured when trying to recall said items. The evoked potentials and hemodynamic activity measured during encoding were found to exhibit reliable differences between subsequently recalled and not recalled items. This effect has been termed the subsequent memory effect (SME). This difference in these specific brain regions determines whether or not a item is recalled. A study by Fernandez et al. has shown that the differences that predict recall appear both as a negative deflection in the rhinal cortex of an event-related potential (ERP) 400 m/sec after stimulus exposure, and as a positive hippocampal ERP beginning 800 m/sec after stimulus onset. This means that recall only occurs if these two brain regions (rhinal cortex and hippocampus) are activated in synchrony.
Factors that affect recall
Attention
The effect of attention on memory recall has surprising results. It seems that the only time attention largely affects memory is during the encoding phase . During this phase, performing a parallel task can severely impair retrieval success.. It is believed that this phase requires much attention to properly encode the information at hand, and thus a distractor task does not allow proper input and reduces the amount of information learned. The lack of proper input can then affect the accuracy of the output. However, when looking at the effect of attention on memory retrieval, it has been found that there are only slight inconsistent impairments. This evidence suggests that memory retrieval is an automatic process. One effect of attention on memory recall is that of latency and retrieval time. This is especially evident in free recall. The competition provided at the time of recall due to divided attention slows down the process, yet has little to no effect on its accuracy. Another possible finding for the minimal effect of divided attention is that the process of recall may include less parallel processing than other memory processes. It has also been observed that different parts of the brain are at work depending on whether one is recalling with full rather than divided attention.