Firstly, what is the phonological loop and where does it fit into a popular model of working memory? To start with, it's probably best to start by activating another component of short-term memory, your visuo-spatial sketchpad. Look at this diagram:
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| Image from cheese360 at Wikimedia Commons |
That is one depiction of the well-known model of working memory put forward by cognitive psychologists Alan Baddeley and Graham Hitch back in 1974. But first, when we see, hear, touch, taste or smell something our sensory memory takes note (beneath our consciousness). As far as language is concerned, we choose to pay attention to it and the information enters working memory, more specifically what are called the visuo-spatial sketchpad (aka scratchpad) and/or the phonological loop, the two stores which contribute to the functioning of working memory.
The visuo-spatial sketchpad, your "mind's eye", processes visual information, either as images or spatial arrangement.
The phonological loop handles sounds, or more particularly of interest to us, spoken language. In the diagram above the central executive is a managing director or orchestrator which has overall control of operations. It decides what to pay attention to. The episodic buffer makes links between the visuospatial sketchpad, phonological loop and long-term memory. It acts as a 'back-up' store which communicates with both long-term memory and the components of working memory. Note that the phonological loop is also involved during reading written material as we sound words in our heads.
The phonological loop, our "mind's ear", is also divided into a phonological (acoustic) store (phonological representations of sounds, syllables, words, phrases and so on) and an articulatory loop (also known as an articulatory rehearsal mechanism). The latter is able to play over sounds in your head, for example when you read aloud or when you rehearse a sentence before you utter it.
By the way, you shouldn't imagine that the model above corresponds in a very precise way to specific areas of the brain, and in any case the brain is very good at adapting to damage in specific areas, but there is evidence, for example, that the phonological store is located in the left inferior parietal cortex, just behind the left ear. The articulatory loop (rehearsal area) seems to be in the left inferior frontal cortex, just in front of the left ear.
Now we know from many research studies that the capacity of the phonological loop is very limited, as is the capacity of working memory as a whole (only around four or so items can be held briefly in working memory before they begin to decay). In addition, research has revealed a number of facts about the phonological loop.
First, we recall lists of short words more easily than long words (the "word length effect"). Second, we learn lists of words which sound the same less well than lists of words which sound different. For example, it would be harder to remember bit, lit, fit, knit, flit and twit, than butter, table, long, quick and monster. It is also the case that when we try to memorise a list of words, we recall the ones at the start and end of the list the best. Interestingly, some research (e.g. Saito (2010) has shown a correlation between a person's ability to recall rhythms and their ability to remember lists of digits.
For the new, unfamiliar sounds of a second language to become embedded in long-term memory, they need to be heard, attended to, processed and pass through working memory into long-term memory for easy retrieval. Having as much information in long-term memory as possible is vital. When we perform a task the load on working memory is much lighter if we can effortlessly call upon lots of resources from long-term memory. Cognitive psychology also tells us that to keep sounds active in working memory and give them a chance to pass into long-term memory, we can rehearse them, e.g. say them out lour or use our inner voice to rehearse them mentally, as when you sound out in your head the pronunciation of words from a list.
From the language teacher's point of view, therefore, this has some clear implications.
1. Paying attention. Our students need to pay attention in the first place! Sounds obvious, but if the language students hear is not understandable (i.e. if it's not comprehensible input) they are far less likely to pay attention. Hence the emphasis which Gianfranco Conti and I place on 95% plus comprehensible input during listening and reading. Therefore, we always need to be extra sure that we are using every trick in the book to make sure students are listening to language they understand - pictures, gesture, objects, facial expression, mime, translation, checking for meaning through formative assessment techniques.
2. Memory span. Since working memory has such a short span, then we need to ensure language is heard in small enough chunks to process, or else memory (the phonological loop) is quickly overloaded.
3. Rehearsal. We need to give students opportunities to rehearse new sounds, syllables, words and phrases to allow these sounds and their written representations to become established. This is the reason for placing emphasis on phonics in the early stages of teaching a new language. Activities such as question-answer and delayed dictation allow students to mentally rehearse utterances so that memory traces can be reinforced. Could we make greater use of rhythm to reinforce memory, e.g. clapping alongside the pronunciation of words?
4. Phonological similarity effect. We should avoid teaching words or phrases which sound similar at the same time. These can cause interference effects which hinder learning. In French it would be wise to avoid presenting j'ai joué (passé composé tense) at the same time or very soon after je joue (present tense). We know how often students conflate these two in oral tests by saying je joué.
5. Phonics. We should encourage lots of reading aloud as a source of phonics practice, as well for general phonological awareness. The well-known Michaela Community School is an example of when large amounts of reading aloud and repetition of sounds produce confident, accurate readers with good phonological memory. The teachers there, and in many other schools, explicitly or implicitly know the role which the phonological loop plays in working memory. This is not the place to describe specific activities, but this was a major focus for us in Breaking the Sound Barrier. How can we make phonological and phonics practice enjoyable?
6. Practice. Since the phonological loop plays such an important role in language acquisition, we should exercise it as much as possible by doing plenty of regular listening. It would be unwise, to sate the obvious perhaps, to skew practice towards reading and writing. In this case spoken fluency and listening skill are less likely to develop. Learners are more likely to retain their native accent and less likely to recognise words and chunks in the stream of sound.
7. Modality effect. Because of what's called the modality effect, we also know that information processed through the visuo-spatial sketchpad can reinforce what is learned through the phonological loop. This is also called dual coding. Psychologists say that these two systems are quite separate, but that the episodic buffer does allow for links to be made between the two stores. Teachers would be wise, therefore, to reinforce sounds with images and actions and not to avoid traditional flashcards and picture stories, just to give two examples.
8. Get itn right early. Some learners seem to have particularly efficient phonological loops, as well as slightly larger working memory spans. This is a genetic phenomenon which is thought to be pretty much unalterable. We know some students are brilliant mimics, being able to overcome their native phonological system with some ease, while others have much more difficulty. This can be seen as a case for working extra hard on phonology and phonics with weaker students. Anecdotal evidence suggests that when students get the sounds right early on, they retain this ability. If bad habits gets formed early, they seem harder to overcome later.
To sum up, what we know about the phonological loop suggests we might prioritise listening in lessons, and doing so in a way which allows processing to occur. This means comprehensible language, delivered in interesting ways to hold attention, and worked on intensively to maximise repetition and build long-term memory. In terms of curriculum planning it may mean covering less, but doing it more intensively for greater retention.
Does the model of memory presented above have weaknesses? It has been pointed out that blind people have excellent spatial awareness, although they have never had any visual information. It may follow that the visuo-spatial sketchpad should be separated into two different components: one for visual information and one entirely separate one for spatial. It has also been pointed out that there is little direct evidence for how the central executive works and what it does. The capacity of the central executive has never been measured.
References
Baddeley, A. and Hitch, G. (1974). Working memory. In G.H. Bower (Ed.), The psychology of learning and motivation: Advances in research and theory (Vol. 8, pp. 47–89). New York: Academic Press.
McLeod, S. A. (2012). Working memory. Available at https://www.simplypsychology.org/working%20memory.html
Saito, S. (2010) The phonological loop and memory for rhythms: An individual differences approach. Abstract available at: https://www.tandfonline.com/doi/abs/10.1080/09658210143000164
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