Echoic memory

Shortly after George Sperling's partial report studies of the visual memories and how they are stored, researchers began investigating its auditory counterpart. The term echoic memory was coined in 1967 by Ulric Neisser to describe this brief representation of acoustic information. It was initially studied using an approach similar to that of Sperling's research. However, modern neuropsychological techniques enabled the ability to estimate the capacity, duration, and location of the echoic memory storage. Using Sperling's model as an analogue, researchers continue to apply his work to the auditory sensory store using partial and whole report experiments. Studies have found that the echoic memory can store memories for up to 4 seconds. However, researchers have proposed differing estimates of the duration of echoic memory storage. However, different durations have been proposed for the existing echo once the hearing signal has been presented. Guttman and Julesz suggested that it may last approximately one second or less, while Eriksen and Johnson suggested that it can take up to 10 seconds. Early work Baddeley's model of working memory consists of the visuospatial sketchpad which is related to iconic memory, and a phonological loop which attends to auditory information processing in two ways. The phonological storage is broken up into two sections. The first is the storage of words that we hear, this tends to have the capacity to retain information for 3–4 seconds before decay, which is a much longer duration than iconic memory (which is less than 1000ms). The second is a sub-vocal rehearsal process to keep refreshing the memory trace by the using one's "inner voice". This consists of the words repeating in a loop in our mind. However, this model does not fully to provide a detailed description of the relationship between the initial sensory input and ensuing memory processes. A short-term memory model proposed by Nelson Cowan attempts to address this problem by describing a verbal sensory memory input and storage in more detail. It suggests a pre-attentive sensory storage system that can hold a large amount of accurate information over a short period of time and consists of an initial phase input of 200-400ms and a secondary phase that transfers the information into a more long term memory store to be integrated into working memory that starts to decay after 10-20s. == Testing methods ==

Partial and whole report Echoic memory is measured by behavioural tasks where participants are asked to repeat a sequence of tones, words, or syllables that were presented to them, usually requiring attention and motivation. The most famous partial report task was conducted by presenting participants with an auditory stimulus in the left, right, and both ears simultaneously. which record changes in activation in the brain by use of electroencephalography. This records elements of auditory event-related potentials of brain activity elicited 150-200ms after a stimulus. This stimulus is an unattended, infrequent, "oddball" or deviant stimulus presented among a sequence of standard stimuli, thereby comparing the deviant stimulus to a memory trace. == Neurological basis ==

Auditory sensory memory has been found to be stored in the primary auditory cortex contralateral to the ear of presentation. and is responsible for attentional control. The phonological store and the rehearsal system appear to be a left-hemisphere based memory system as increased brain activity has been observed in these areas. The major regions involved are the left posterior ventrolateral prefrontal cortex, the left premotor cortex, and the left posterior parietal cortex. Within the ventrolateral prefrontal cortex, Broca's area is the main location responsible for verbal rehearsal and the articulatory process. The dorsal premotor cortex is used in rhythmic organization and rehearsal, and finally the posterior parietal cortex suggested a role in localizing objects in space. The cortical areas in the brain believed to be involved with auditory sensory memory exhibited by mismatch negativity response have not been localized specifically. However results have shown comparative activation in the superior temporal gyrus and in the inferior temporal gyrus. == Development ==

Age-related increases in activation within the neural structures responsible for echoic memory have been observed showing that with age comes increased proficiency in the processing of auditory sensory information. In a study, it was found that when words were presented to both younger subjects and adult subjects, the younger subjects out performed the adult subjects as the rate in which the words presented were increased Affect echoic memory capacity may be independent of age. == Problems ==

Children with deficits in auditory memory have been shown to have developmental language disorders. Further research on stroke victims with a reduced auditory memory store has shown that listening to daily music or audio books improved their echoic memory. This suggested a positive effect of music in neural rehabilitation after brain damage. ==See also==