User:David Lilley90/sandbox

Verbal memory is a term used in cognitive psychology, defined as the ability to encode, store and retrieve information relating to the acoustic (sounds) qualities of numbers, letters and words. This definition also includes any other abstractions involving language and is different from non-verbal memory, which looks at how information is encoded, stored and retrieved in any modality not related to language (spatial information, for instance). Encoding refers to the ability to alter information into a usable form by the brain (in this case, verbal encoding). Storage refers to the ability to hold information in one’s brain for later use and retrieval is the ability to recall previously stored memories. Verbal information processing is possible at short time intervals, in the order of seconds (short-term memory) and at long time intervals, from minutes to years (long-term memory). The distinction of verbal memory as separate from other forms of memory is evidenced by neuroimaging studies that show different areas of activation for verbal information compared to visual and spatial information.

Verbal Memory Research
An issue surrounding short- and long-term memory is that research in this area uses mostly verbal information as a means to test hypotheses. That is, there is a distinction between the use of verbal and visuospatial material in this research area. So when referring to short- or long-term memory, it could be mistaken for verbal short- or long-term memory. Moreover, research has been conducted into the way visual information, spatial information and olfactory information is encoded, stored and retrieved; terms that also fit under the short- and long-term memory umbrella. Consequently, the current page will specifically focus on verbal material processing in short-term and long-term memory. This distinction is further emphasised by Alan Baddeley’s research into working memory. In his model, he proposes a distinction between verbal and visuospatial processing at short-time scales (order of seconds). A phonological loop deals with the manipulation of verbal material whilst a  visuospatial sketchpad deals with visual and spatial information.

Encoding
Encoding of verbal short-term memory occurs acoustically. That is, sounds (verbal content) that are similar to one another will be more easily forgotten in short-term memory compared to sounds that are not linked in this way (B, C and T versus X, Y and Z). This idea extends to more complex phonetic constructions such as language, where words are linked semantically as well as acoustically. Research has shown that participants perform significantly poorer at retrieving acoustically similar words than semantically similar words from a short-term store when asked to repeat a list of recently memorised words. This effect also occurs in the situation where verbal information is presented visually, reiterating the notion that poorer retrieval is a direct consequence of the encoding process rather than the modality of presentation.

Storage
Verbal information in short-term memory is stored consciously. That is, the participant will be aware of the information that is held in mind and once an item cannot be retrieved, it is said to have decayed. There is a limited duration and capacity for which verbal information can be kept in mind without rehearsal before this process of decay becomes evident. Decay begins to occur almost immediately (around 2 seconds after stimulus disappearance) and lasts for 20 seconds before a list of items cannot be recalled. The capacity of verbal short-term memory has also been evidenced by research. That is, the amount of information that can be kept in consciousness at any one time has been shown to be limited. Originally thought to be around seven words and nine numbers, research has more recently shown that the capacity for words is in fact much smaller, around 4 chunks of information. Other research has also shown that the capacity for numbers is longer than words.

Retrieval
Due to the nature of decay for verbal information in short-term memory, there are effects that increase (and decrease) one’s ability to retrieve recently memorised information. The two most well-known are word length   and  word frequency effects. The word-length effect follows the notion that longer words will take longer to process and thus will have a greater likelihood of decay by the time it comes to retrieval. The word-frequency effect notes that words of high frequency used within a language will have a greater chance of being retrieved from memory than rarer words.

Encoding
Verbal information is encoded semantically into long-term memory. Research by Baddeley showed that participants performed worse on a memory task that involved learning of semantically linked words than acoustically linked words in long-term memory. This experiment formed part two of his papers showing a distinction between short-term and long-term verbal information encoding.

Storage
As with short-term memory, there is a duration and a capacity for which verbal information can be stored at longer time periods. Although not much research has been conducted into this area due to the difficulties with testing long-term memory effects, findings suggest that verbal information in long-term memory lasts for many years. Research by Bahrick found that participants, using  free recall, were still able to name classmates 48 years after graduation. The capacity for verbal information is also robust, with research suggesting that humans maintain an unlimited capacity.

Retrieval
Verbal information is also subject to retrieval effects in long-term memory. It has been shown by Kensinger that the retrieval process for verbal information differs depending on the type of emotion evoked. That is, words that are emotionally negative are more easily retrieved than words that are emotionally neutral. Moreover, it has been shown that the vividness (the detail) is better remembered than neutral words.

Neural Correlates
There is a distinction between verbal and visual memory processing in the brain. Research has shown that verbal content is mostly left-lateralised. Active regions include Broca’s area, an important component for refreshing a short-term memory trace via rehearsal. Research has also been conducted into potential differences between short- and long-term memory processing in the brain, with results suggesting that similar neural networks are involved for encoding, storage and retrieval.