Jennifer Morris – 0206060264 PSY - 203
Working memory serves more than one function. Discuss.
Baddeley and Hitch 1974 (Citied in Baddeley 1993) proposed that the concept of short-term memory should be replaced with that of working memory to account for their findings from amnesic patients who performed poorly on digit span tasks . These patients could not hold items in their short-term store but seemed to show signs of long-term learning which contradicted earlier models of memory including that of Atkinson and Shiffrin’s 1968 multi-store model (Cited in Baddeley 1990). Working memory is believed to act as a temporary storage system which holds in coming information from the senses and most recently stimulated information from the long term memory, it then manipulates the information in and out of the short-term memory. Baddeley and Hitch’s working memory model is not a single unitary system but one that comprises of three components. Firstly there is a core system that controls the overall system called the central executive, which directs responses and coordinates various activities. The central executive is assisted by two slave systems, the phonological loop which is an auditory speech based system which holds inner speech for verbal comprehension, and the visuo-spatial sketchpad which holds and manipulates spatial and visual information (Eysenck & Keane 2000). The working memory has several functions and is believed to be involved in many aspects of learning, reasoning and comprehending.
The phonological loop is the most extensively explored element of the working memory. It comprises of two components a phonological store that is capable of holding speech-based information and an articulatory control process based on inner speech that gives access to the phonological store. Words that are presented auditorily can gain direct access to the phonological store regardless of whether the articulatory control system is used, whereas the visual presentation of words only allows indirect access to the phonological store through sub-vocal articulation (Eysenck and Keane 2000). It is believed that sub-vocalization plays an important role in learning to read; people often ‘hear’ what they are reading by some form of ‘inner voice’. However from the evolutionary perspective reading has surely developed too recently for this to be the soul function of the phonological loop system. A more plausible explanation for its development seems to be the idea that it plays a key role in speech production and language comprehension. Vallar and Baddeley (1984) studied the comprehension of both spoken and written dialogue in one Italian patient P.V. who had a very specific deficit in her auditory short-term memory (STM) performance following brain damage. She had a digit span of only two but had a sentence span of approximately six words and could answer simple sentences rapidly and accurately, even when sentences were made longer her understanding was still clear. However she did experience problems when longer sentences where presented that required both the retention of words and for the words to be processed in the correct order for accurate comprehension. For example ‘The world divides the equator into two halves, the northern and the southern’. P.V. is able to comprehend normally provided material does not require retention of information over many intervening words; when this is required her performance is seriously impaired. This therefore suggests that the phonological store does play a role in language comprehension, but mainly for complex or demanding material. However we must remember that P.V.’s phonological store was not destroyed only impaired therefore her six word span may be enough to cope with simple language whereas someone with no phonological store may be completely unable to comprehend speech.
