People with dyslexia often have differences in certain types of memory compared to those without dyslexia. In verbal short-term memory, which involves temporarily storing and recalling information presented verbally, people with dyslexia may struggle to remember spoken information like instructions, new vocabulary words, or names. They may also have challenges with working memory, which involves manipulating and acting on information held in the mind. Poor working memory can make it hard for people with dyslexia to juggle multiple pieces of information at once. However, not all memory functions are impaired in dyslexia. Some people with dyslexia have average or even superior long-term memory for experiences and facts. Their verbal short-term and working memory challenges primarily involve processing language-based information. With the right supports, people with dyslexia can develop effective memory and learning strategies.
Human memory is a complex cognitive system that allows us to encode, store, and retrieve information over time. There are multiple memory systems that serve different functions and operate in distinct ways. This article will provide an overview of the major human memory systems and discuss how deficits in these systems may impact children with dyslexia.
Adapting and Finding Strengths:As a dyslexic and dysgraphic student, I struggled tremendously with basic print concepts in reading and writing. My printed letters were often unclear, illegible, and full of reversals. I had great difficulty remembering the correct letter shapes and orienting them properly on the page. For me, print did not come naturally.It wasn't until I started learning cursive that things finally clicked. With cursive writing, the flowing hand motions seemed to activate my muscle memory and kinesthetic learning style. As I practiced tracing the cursive letters, my hand grew accustomed to the strokes and patterns. I was drawing each letter from memory, not having to think step-by-step about how to form it.Over time, writing words in cursive also improved my spelling. The continuous motions reinforced the sequences of letters flowing together in words. I was internalizing the spelling through my hand's natural movements, rather than just visual memorization. Studies show that engaging the motor cortex through hands-on learning activities like cursive can enhance memory and learning in dyslexic students.For me, cursive was a game-changer. The motor practice strengthened my visual-spatial memory and cemented letter forms in my mind in a way that print alone never could. Although legible print was a struggle, my cursive became beautiful and effortless. Tapping into my natural kinesthetic i memory and ntelligence opened up my abilities as both a reader and writer.
Types of Memory Systems
Sensory Memory
Sensory memory refers to the brief storage of sensory information. This memory system allows sensory information to be briefly retained after the original stimulus is no longer present. For example, iconic memory deals with briefly stored visual information while echoic memory refers to brief storage of auditory information (1). Sensory memory is an ultra-short term memory system that decays rapidly and has a large capacity. It provides a buffer so that information can be passed on for further processing and encoding into short-term memory (2). Studies suggest that iconic memory may last for about 250 milliseconds while echoic memory may last up to about 2 seconds (3). Individuals with dyslexia do not appear to have deficits in sensory memory systems.
Short-Term Memory
Short-term memory (STM), also known as working memory, involves the temporary storage of information for a short period of time, usually seconds. STM has limited capacity, holding about 7 (plus or minus 2) items for around 15 to 30 seconds before the information decays and is lost (4). STM allows information to be recalled in the same sequence in which it was presented. There are two components of STM: the phonological loop which stores verbal and acoustic information, and the visuospatial sketchpad which stores visual and spatial information (5).
Research suggests that STM deficits, particularly in the phonological loop component, are common in individuals with dyslexia (6). Children with dyslexia often show impairments in tasks that involve repeating words, letters, or numbers in sequence. This indicates reduced phonological short-term memory capacity. Some studies also find visuospatial sketchpad deficits in dyslexia, with impaired ability to store and manipulate visual and spatial information over short periods (7). The STM deficits in dyslexia are thought to play a key role in impairments in learning new words, reading, and language development.
Long-Term Memory
Long-term memory (LTM) refers to the relatively permanent storage of information over hours, days, weeks or years. LTM has essentially unlimited capacity and information can persist without decay for many years (8). There are two main subtypes of LTM:
1. Declarative (Explicit) Memory: Declarative memory includes the storage of facts, events and data that can be consciously recalled. This is further divided into semantic memory for general knowledge and episodic memory for events associated with a particular context (9).
2. Nondeclarative (Implicit) Memory: Nondeclarative memory includes skills, habits, conditioned responses and emotional memories that are expressed through performance rather than conscious recall (10).
Studies show that individuals with dyslexia do not tend to show generalized impairments in long-term declarative or explicit memory systems (11). However, they may demonstrate weaker learning and memory for verbal information such as words and phonological material, reflecting phonological processing weaknesses. In contrast, nondeclarative and implicit long-term memory systems are relatively intact in dyslexia. Skills and habits learned through repetition, such as playing a musical instrument, tend to be well retained (12).
Visual Memory
Visual memory involves the encoding and storage of visual information and images. It consists of a number of components:
- Visual short-term memory (VSTM) – Temporary storage of visual details and features
- Visual working memory – Active manipulation of visual images held in mind
- Visual long-term memory - Long-term storage of visual representations and images
While some studies show no differences in basic VSTM capacity in dyslexia, others provide evidence for deficits in storing sequential visual information (13). Individuals with dyslexia may also have reduced visual working memory capacity, negatively impacting manipulation of visual images. However, long-term visual memory appears mostly intact in dyslexia.
Auditory Memory
Auditory memory involves the registration, storage and retrieval of auditory information. Key components include:
- Echoic memory – Ultra-short storage of auditory information
- Verbal short-term memory – Short-term storage of verbal acoustic information
- Verbal working memory – Active processing and manipulation of verbal-acoustic information
- Long-term auditory memory – Long-term memory for verbal information and auditory representations
As covered earlier, auditory echoic memory is intact in dyslexia, but deficits are consistently found in verbal short-term memory and working memory manipulations (14). Children with dyslexia show particular difficulty repeating back verbal information in sequence due to impaired phonological short-term memory. Long-term memory for verbal labels and names may also be selectively weaker. However, music memory and long-term memory for environmental sounds appear unaffected.
Procedural Memory
Procedural memory involves the implicit learning and long-term retention of motor and cognitive skills. This includes physical skills like riding a bike or playing a sport, as well as cognitive routines like reading or solving math problems. Procedural memory does not require conscious access or declarative knowledge about the skill (15). This nondeclarative memory system is relatively unaffected in dyslexia. Children with dyslexia are able to adequately develop motor skills and routines through repetition and practice. However, converting declarative fact knowledge into skilled procedures can be challenging.
Autobiographical Memory
Autobiographical memory involves recollection of personal experiences and specific events from an individual's life. It is considered an explicit memory system as it relies on conscious retrieval (16). Some studies have found that individuals with dyslexia may have overgeneral autobiographical memory and provide less specific details when recalling past events (17). However, this effect is not consistently observed across studies. Any deficits seen are relatively minor and do not profoundly impact everyday autobiographical memory.
Other Memory Systems
A few other types of memory that may be impacted in dyslexia include:
Working memory – As detailed earlier, deficits are commonly observed in phonological aspects of working memory involved in actively manipulating verbal information held in mind (18).
Episodic memory – While episodic memory is largely intact, memory for verbal information and sequences may be selectively weaker (19).
Spatial memory – Some studies provide evidence for impaired spatial memory and reduced ability to remember locations, although findings are mixed (20).
Prospective memory – This involves remembering to carry out intended actions in the future. Individuals with dyslexia may show some deficits in time-based prospective memory tasks (21).
In summary, dyslexia appears to selectively impact short-term, working, and episodic memory systems involving phonological and verbal processing. Long-term memory systems remain mostly intact, with the exception of weaker verbal learning. Visuospatial, motor skill, and autobiographical aspects of memory are relatively unaffected. This fits with dyslexia as a specific learning disorder primarily affecting phonological coding and language skills.
Neural Correlates
Converging research using neuroimaging techniques provides insights into the neurological underpinnings of memory deficits in dyslexia. Structural MRI studies demonstrate reduced gray matter volume in left hemisphere posterior brain regions related to phonological processing, verbal working memory, and reading, including the parietal, temporal, and occipital lobes (22). Functional MRI studies also show reduced activation in left perisylvian areas during verbal working memory and phonological processing tasks (23).
Additional neurological correlates include abnormalities in the fronto-parietal attention networks as well as cerebellar regions during challenging working memory tests. Together, these findings map onto the behavioral manifestations of memory impairment in dyslexia and point to biological origins of phonological and language processing weaknesses.
Cognitive Mechanisms
Several cognitive mechanisms have been proposed to explain the specific memory deficits found in dyslexia:
- Impaired phonological representations - Weak phonological processing abilities may stem from poorly specified speech sound representations in long-term memory (24). This impacts coding of verbal information into short-term memory.
- Reduced verbal rehearsal - Deficits in subvocal rehearsal processes could limit active maintenance of verbal material in short-term memory (25).
- Executive dysfunction - Working memory and attentional control deficits point to broader executive function weaknesses affecting manipulation of stored information (26).
- Cognitive inefficiency - Individuals with dyslexia may require more effort and cognitive resources to process phonological material, limiting working memory (27).
Overall, memory deficits in dyslexia appear to arise from the interaction of multiple cognitive mechanisms and information processing challenges. However, phonological representations and rehearsal processes play a critical role.
Developmental Impacts
Memory deficits associated with dyslexia can have significant developmental impacts on learning in children:
- Language delays – Impairments in phonological memory and verbal rehearsal can slow vocabulary growth and sentence development (28).
- Reading difficulties – Weak phonological representations and verbal coding hinder learning letter-sound relationships and decoding skills (29).
- Math learning problems – Remembering math facts and calculation steps relies on verbal working memory capacities (30).
- General academic struggles – Limited short-term memory and working memory abilities affect learning and remembering new information across subjects (31).
- Poor memorization skills – Children with dyslexia often struggle with memorizing facts, lists, and procedures (32).
On the positive side, visual, physical, emotional, social and long-term memory abilities remain largely intact in dyslexia. Capitalizing on these strengths can help promote educational success. Targeted memory interventions are also beneficial.
Interventions and Accommodations
Several strategies and interventions can help compensate for memory deficits in dyslexia:
- Phonological training – Activities focused on developing speech sound awareness and representations remediate core weaknesses (33).
- Rehearsal strategies – Teaching verbal rehearsal techniques enhances short-term retention of verbal material (34).
- Working memory practice – Computerized training and memory games improve storage/manipulation capacities (35).
- Multisensory learning – Using visual, auditory, written and kinesthetic modalities capitalizes on retained memory abilities (36).
- Memory aids – Checklists, planners, maps, timers and recorded instructions serve as external cognitive supports (37).
- Reducing load – Breaking information into smaller chunks and allowing processing time limits overwhelming memory (38).
- Providing notes – Copies of lecture slides, notes and handouts prevents reliance on short-term recall (39).
Implementing research-based interventions, accommodations and supports allows students with dyslexia to maximize their memory abilities and academic achievement.
Conclusion
In summary, individuals with dyslexia demonstrate specific deficits in short-term, verbal working, and phonological aspects of memory. Long-term storage systems remain relatively intact. Neuroimaging points to biological correlates of memory impairment centered in left hemisphere language regions. Cognitive factors include poor phonological representations, reduced verbal rehearsal abilities, and executive dysfunction. Developmentally, memory deficits can impact language, reading, and learning. But targeted interventions can improve memory capacities and provide accommodations to promote student success. Understanding the nature of memory impairment in dyslexia is key for creating effective educational supports.
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