Memory matters for Specific Learning Difficulty assessments

It would be impossible to understand the nature of Specific Learning Difficulties or their impact without considering the influence of memory, as learning and memory are intricately linked. Learning is about acquiring new behaviours and information, and memory is about the processes involved in retaining and retrieving what has been acquired. It would be rare to find a cognitive assessment battery that did not contain a test of memory. Not only is memory recognised as a powerful predictor of academic progress, shown to be more powerful than IQ (Alloway & Alloway, 2010), but it is also fundamental to every aspect of our lives.

Different aspects of memory can be tested in a multitude of ways, however test selection and interpretation of findings can be challenging. Terminology varies widely, as does the extent to which test performance may be influenced by other areas of cognition; for example, attention and language. 

Different types of memory are often presented as dichotomies or pairs of contrasting features. Some of the most common considerations are:

• the nature of the stimulus presented
• how long it needs to be retained in memory
• whether the information held in memory needs to be recalled exactly as presented, or whether further manipulation or transformation of that material needs to take place. 

Pairs of terms relating to these contrasting features are discussed below, along with other related terms. 

The terms auditory and visual memory differentiate memory for what is heard from memory for what is seen. 

In practice, with respect to auditory memory, it is usually memory for the speech-sound based information that makes up spoken words that is of interest (phonological information), and the term phonological memory is therefore widely used too – both for memory of real words and of ‘nonwords’ (made up words with unfamiliar sequences of sounds). 

Another term in frequent use is verbal memory. Verbal means ‘related to words’ and so verbal memory can actually be for written or spoken words. In the context of oral language however, since spoken words are made up of phonological information, it is often used interchangeably with the term phonological memory. When the information heard has no meaning however, as in the case of nonword repetition tests, it is common to refer to phonological memory, rather than verbal memory. 

Tests of visual memory require the test-taker to encode, maintain and retrieve visual information, for instance geometrical shapes or parts of shapes, location of items in space or details of a picture. When information about location as well as form needs to be recalled, then the term visual-spatial memory may be used. 

In their narrowest sense, the terms short-term and long-term memory simply refer to the length of time information is held in mind. Short-term memory is about holding it briefly – usually for a few seconds, in ‘immediate awareness’, whereas long-term memory refers to the storage of information for longer periods of time – perhaps minutes or even years.

Two distinct elements can be identified when information is stored for short periods of time: the holding of that information and the capacity to manipulate or transform it in some way while holding it – its use as a ‘mental workspace’. 

Within Cattell-Horn-Carroll (CHC) theory, as refined by McGrew (1997), these were termed memory span and working memory capacity respectively and were both components of the ‘Short-Term Memory factor’ (Gsm) - contrasting with the ‘Long-Term Storage and Retrieval factor’ (Glr). In 2012, Sneider and McGrew followed other cognitive psychologists in adopting terminology that emphasised the manipulation rather than maintenance of information in short-term storage and the name of the factor relating to short-term storage became ‘Short-Term Working Memory’ factor (Gwm). 

Within other theoretical frameworks, the ‘holding’ and ‘manipulating’ components are not only conceptualised as distinct cognitive functions but referred to as short-term memory and working memory respectively.

One of the best-known models of memory was developed by Baddeley in the 1970s and refined in subsequent decades. Initially it showed the inter-relationship between the short-term storage and manipulation of auditory and visual information, and how attention interacts with memory. The model consisted of a ‘phonological loop’ where auditory information was envisaged to be stored (and maintained through subvocal rehearsal), a ‘visuospatial sketchpad’ for holding visual and spatial information, and the ‘central executive’ which controlled attentional resources, so that the two types of information could be integrated and used effectively.  

In Baddeley’s early work, he argued that short-term memory was sound-based and long-term memory was semantic or meaning-based, but he added an ‘episodic buffer’ to his model in 2000s to act as a bridge between short-term and long-term memory. Not only could information reach long-term memory via short-term memory, but stored knowledge was acknowledged as having a great influence on short-term working memory performance. Language knowledge (in long-term memory) is known to be particularly important in auditory memory tests. Memory for real words is increased when they are familiar, frequent in the language and concrete. For nonwords, likeness to real words and the presence of common sounds sequences facilitates retention and retrieval. Those with larger vocabularies tend to be more accurate at recalling both words and nonwords. Vocabulary size also helps with remembering sentences, though grammatical knowledge helps even more. 

In addition to language, images stored in long term memory can be used to fill in blanks in visual representations in the visuospatial sketchpad, and routines and past actions can be recalled to create strategies for current problems.

Alloway, T. P., & Alloway, R. G. (2010). Investigating the predictive roles of working memory and IQ in academic attainment. Journal of Experimental Child Psychology, 106(1), 20-29

Baddeley, A.D. and Hitch, G.J., 1974. Working memory. In: G.H. Bower (ed.) The Psychology of Learning and Motivation. Vol. 8. New York: Academic Press, pp. 47–89

Baddeley, A., 2000. The episodic buffer: a new component of working memory?Trends in Cognitive Sciences, 4(11), pp.417–423

McGrew, K.S., 1997. CHC Theory of Cognitive Abilities: First Generation Definitions. In: D.P. Flanagan & P.L. Harrison (eds.) Contemporary Intellectual Assessment: Theories, Tests, and Issues. 1st ed. New York: Guilford Press, pp. 136–182

Schneider, W.J. and McGrew, K.S., 2012.The Cattell‑Horn‑Carroll model of intelligence. In: D.P. Flanagan and P.L. Harrison, eds. Contemporary Intellectual Assessment: Theories, Tests, and Issues. 3rd ed. New York: Guilford Press, pp.99‑144