Cognition and Instruction/Working Memory and Learning Disabilities

According to the World Health Organization (WHO) it estimated 1 in every 160 children will be diagnosed with Autism Spectrum Disorder (ASD) and currently 39 million individuals are living with an Attention Deficit Hyperactivity Disorder (ADHD) diagnoses . Working Memory is a system used to implicate the process of encoding, decoding and maintenance of our memory (Figure 1)(specifically short-term memory) while , at the same time maintaining activity and accessibility . Research suggests developmental disabilities such as those as defined in the Diagnostic Statistics Manual of ASD and ADHD impact working memory. This chapter, within the framework of Baddely's working memory model attempts to understand the inner workings of these prevalent disorders.

Working Memory

Figure 1. This is a FMRI scan of a brain during working memory task.

Many types of developmental disabilities can be traced at least partially to problems with the memory. Problems with working memory subsystems seem to lie behind the way in which patients with autism become confused over large amounts of information, and deficiencies in working memory are also implicated in attention deficit hyperactivity disorder. A number of other developmental disabilities, such as Williams Syndrome, Down syndrome, and dyslexia can also be connected with improper functioning of memory.  Below we focus on autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) because the role of memory in these two disorders has been studied in detail, allowing us to use them to shed light on how the memory functions in practice.

Information Processing Theory

The traditional concept of memory saw it as a simple container that stored what the senses dumped into it for later use by the brain. With the advent of electronic data processing systems, the metaphors drawn from these have become the most popular ways to conceptualize memory. These metaphors are powerful and suggestive, but they can also be misleading, since the brain differs in many ways from a computer.

One of the main reasons for the use of data processing metaphors is that memory is a function that cannot be easily linked with specific parts of the brain. Thought is seen as information processing, and a key component of information processing is storage and retrieval. Information that is to be stored for the long term has to be encoded, processed to make it suitable for storage. The efficiency of this encoding can be enhanced by emotional arousal.The concept of encoding and decoding of memories suggests that they are not simply raw information but are constructed by the brain when recalled, and the construction may be influenced by the circumstances under which they were recalled.

Again reflecting the metaphor of an electronic computer, information processing theory saw memory as the interaction of several subsystems, each devoted to one specific task, that passed information one to the other as needed. The requirement for conscious attention by some processes means these systems have a limited capacity. The limited amount of memory affect learning and it caused the learning disabilities. The disabilities of grabbing on to memory is associated with autism and ADHD.

The Modal Model and Disability

The modal model (Figure 2), also known as the multi-store or Atkinson-Shiffrin model (from the researchers who first put it forward in 1968) is assumed by all varieties of information processing theory. It postulates different mental subsystems, each with a distinct function, that support and feed information to each other. The basically modal structure of the memory was supported by cases of brain damage that affected different parts of the memory unequally.  Most versions of the modal model were divided into three major sections: sensory memory or sensory register, short-term memory, and long-term memory.  As noted below, the concept of “short-term memory” is now obsolete. The unequal part of memory challenges students' ability to learn simultaneously, ability to grasp the knowledge.

Three-part Working Memory Model

Figure 3. The three- part working memory model.

It was obvious that something had to be carrying out the processes assigned to short-term memory. However, researchers gradually became frustrated with the concept’s inability to provide a model of how these processes took place.  Thus, beginning in the 1970's, the “short-term memory” model was supported or replaced by a function labeled “working memory.” The “working memory” holds the information and images that the person in question is engaged with at the moment. Figure 3 presents the three-part working memory model.

There are many variations of this model, reflecting the uncertainty researchers have about how exactly it functions. However, it is generally agreed that the working memory is tightly linked with the long-term memory, since past knowledge has a very strong influence on conceptions in the present. It is also agreed that unlike the concept of short-term memory, which was thought to store information passively in an average of seven “slots” and transmit it unchanged, the working memory is active, not passive, making it central to the construction of meaning.

The most influential scheme for the working memory was put forward by Baddeley.  This divided the working memory into three components: an executive control system, an articulatory loop, and a visuo-spatial sketch pad.  This multi-component scheme is supported by a number of pieces of experimental evidence, such as the KF Case Study, where an accident severely impaired verbal processing while leaving visual processing almost intact. This strongly implies that verbal and visual processing are controlled by two different systems.  It is also supported by the observation that visual and phonemic tasks can be carried out at the same time with relatively little impairment, showing that they do not depend on the same mental resources.

Central Executive

The central executive or executive control system has been compared to a director controlling the activities of two subordinates, the phonological loop and the visuo-spatial sketchpad. It oversees the functions of the working memory, selects information and strategies, and decides what the working memory will concentrate on. It coordinates performance on different tasks, decides among retrieval strategies, switches focus among different inputs, and interacts with the long-term memory to retrieve and work with information.

Despite its critical importance, little is known about the detailed working of the central executive. It has been criticized as “little more than a homunculus,” a humanoid “boss” that coordinates all the other functions of the system.  Whether it carries out its various functions as a single coordinated system or a collection of independent subsystems is not clear.

Phonological loop

The phonological loop deals with spoken and written information. It is a passive short-term storage system for information that is received by reading or hearing.  Information is stored in an articulation code, which means that written data must be converted before it can be retained. Aural data goes directly into the store.

The phonological loop is divided into two parts. The first is the phonological store or “inner ear,” governing speech perception, which can hold aural information (spoken words) for several seconds. The second is the articulation control process, or “inner voice,” which is in charge of producing speech, and which can rehearse and store input from the phonological store.

Visuo-spatial sketchpad

The visuo-spatial sketchpad or the “inner eye” deals with visual information and spatial concepts. It is a passive short-term storage system for visual and spatial information received through the eyes. It is responsible for situating a person in space, so that s/he can move through other objects without constantly colliding with them. Information is stored as images, which must be interpreted to retrieve specific details. It also creates and manipulates mental images, and turns material in the long-term memory back into usable information on spatial arrangement.

The visuo-spatial sketchpad appears to function even in individuals that have never enjoyed the power of sight, since such individuals have clear concepts of spatial distribution. This indicates that concepts of spatial distribution are independent of visual input. It has thus been suggested that the visuo-spatial sketchpad be split into two independent functions, one concerned with purely visual data, and another with spatial concepts.

Developmental Disabilities

Autism Spectrum Disorder (ASD)

Autism spectrum disorder (ASD) and autism are both general terms for a group of complex disorders of brain development and such classified as intellectual and developmental disability. These disorders are characterized, in varying degrees, by difficulties in social interaction, verbal and nonverbal communication, repetitive behaviors and difficulties in motor coordination and attention. Because of overlap and variability in symptoms, The DSM IV introduced the concept of autism spectrum disorder as opposed to a stand alone disorder.

Figure 4. Prevalence Rates and Incidence rates (U.S.)

While ASD occurs more often in boys than girls, early detection nonetheless is critical in diagnosis because proactive interventions have shown considerable improvements in areas such as language and social skills. Often this early detection is a result of statistically significant diminished capacities often referred to as impairments. Some early signs of impairment include: Communication (social), behaviors (verbal and non-verbal) and interests. While each pattern is unique, most common symptom is diminished capacity of language. DSM IV suggests three main types of ASD:

• Asperger's syndrome (AS)
• Pervasive developmental disorder, not otherwise specified (PDD-NOS)
• Autistic disorder (AD)

The DSM V while it made changes to ASD descriptions, further research should be considered when assessing the changes. Listed below are some of the common autism disorders.

Asperger's Syndrome (AS)

The mildest form of autism, Asperger's syndrome (AS), involves repeated interest, discussion on a specific topic. Children with AS often show great impairment in social skills and uncoordinated; however, above average intelligence has also been reported. High functioning Asperger syndrome (HFAS) if left unsupported can lead to depression and anxiety in later life.

Pervasive Developmental Disorder, Not Otherwise Specified (PDD-NOS)

Because of the generalized description, captures most children and is considered more severe than AS (but less severe as ASD). PDD-NOS symptoms include (but not exclusive) impaired language skills, social interaction and later age of onset. Difference of PDD-NOS from AS and Autism disorder (AD) include fewer repetitive behavior and variability of symptoms offers a challenge to diagnosis.

Autism Disorder

Children who meet more rigid criteria for a diagnosis of autism have autistic disorder. They have more severe impairments involving social and language functioning, as well as repetitive behaviors. Often, they also have mental retardation and seizures. Common symptoms while similar to AS and PDD-NOS also include absences of name recognition and use of single or two word phrases.

While ASD includes many subtypes and often the numbers can be underestimated because of variability, Figure 4 gives an overview of prevalence and incidence rates in the United States (1993-2003). This suggests ASD continues to be persuasive and increasing exponentially (compared to other disabilities). While ASD is the most common of the developmental disabilities, the second most prevalence learning disability is attention deficit hyperactivity disorder.

Attention deficit hyperactivity disorder (ADHD)

According to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, DSM V, it states the diagnostic features of ADHD. People with ADHD would show a persistent phenomenon of Inattention and/or hyperactivity-impulsivity that affect development and/or normal functioning. (Reference table 1)

Inattention: 6 or more symptoms present for children who are below 16 years of age, or 5 or more symptoms must be presented for adolescents older than 17; these symptoms of inattention have been present for at least 6 months, and they are inappropriate for developmental level:

Hyperactivity and Impulsivity: 6 or more symptoms present for children who are below 16 years of age, or 5 or more symptoms must be presented for adolescents older than 17; these symptoms of hyperactivity-impulsivity have been present for at least 6 months to an extent that is disruptive and inappropriate for the person’s developmental level:

•           Often fails to give close attention to details or makes careless mistakes in schoolwork, at work, or with other activities. •           Often has trouble holding attention on tasks or play activities. •           Often does not seem to listen when spoken to directly. •           Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace . •           Often has trouble organizing tasks and activities. •           Often avoids, dislikes, or is reluctant to do tasks that require mental effort over a long period of time. •           Often loses things necessary for tasks and activities . •           Is often easily distracted •           Is often forgetful in daily activities.

•           Often fidgets with or taps hands or feet, or squirms in seat. •           Often leaves seat in situations when remaining seated is expected. •           Often runs about or climbs in situations where it is not appropriate (adolescents or adults may be limited to feeling restless). •           Often unable to play or take part in leisure activities quietly. •           Is often "on the go" acting as if "driven by a motor". •           Often talks excessively. •           Often blurts out an answer before a question has been completed. •           Often has trouble waiting his/her turn. •           Often interrupts or intrudes on others

In addition, the following conditions must be met:

•           Several inattentive or hyperactive-impulsive symptoms were present before age 12 years.

•           Several symptoms are present in two or more setting, (such as at home, school or work; with friends or relatives; in other activities).

•           There is clear evidence that the symptoms interfere with, or reduce the quality of, social, school, or work functioning.

•           The symptoms are not better explained by another mental disorder (such as a mood disorder, anxiety disorder, dissociative disorder, or a personality disorder). The symptoms do not happen only during the course of schizophrenia or another psychotic disorder.

Sub-types of ADHD

There are three sub-types of ADHD that categorized by the different categorize of ADHD.

•           Predominantly Hyperactive-Impulsive Type: in order to fulfill this sub-type, in the past six weeks, the person has filled the entire requirement for symptoms of Hyperactivity-impulsivity, but not the symptoms of inattention

•           Predominantly Inattentive Type: In this sub-type, the person has filled the entire requirement for symptoms of inattention, but not the symptoms of Hyperactivity-impulsivity.

•           Combination Type: In this sub-type, the person has filled both requirement for the symptoms of Hyperactivity-impulsivity and inattention. This is the most common type of ADHD.

With these definitions of ADHD and ASD in mind (including symptoms), it is important to consider its relationship with working memory.

Autism Spectrum Disorder and Working Memory

Approximately seven percent of children suffer with literacy disorders such as Autism Spectrum Disorder (ASD) and ADHD  Working memory is a fundamental function for the developmental process which is known to impact the neuro-cognitive domain with impairments  Widely held beliefs on ASD and working memory suggest deficits in phonological loop processing, visuo- spatial challenges and inability to regulate executive functioning Controversial debate related to heterogeneity of ASD subjects and the various components of working memory function continue today.  For example, a child with ASD may show attention to a specific object (e.g. zippers) while another child with similar diagnosis would not react to the same object (zipper). The second child may show interest in a bike instead. This suggests an impairment with the phonological loop. While ASD and working memory are complex, current research continues to focus on identifying specific impairments and its relationship to the different components of working memory when considering solutions in the instructional environment.

ASD and Central Executive

The central executive is the "most important component of working memory" because it is responsible for monitoring and coordinating the operation of the slave system (phonological loop, visuo-spatial sketch pad) and relates to long term memory

ASD's impairments in social interaction, verbal, non-verbal communication, and restrictive behaviors appear in early childhood and persist in later life. Hill & Frith (2004) (as cited by Cui et al.) suggest this is a result of executive dysfunction. Conflicting research suggests ASD dispute a relationship to central functioning because working memory may also be influenced by factors such as age, IQ, task measured which is often not accounted for in research literature. However, since Hill & Frith were able to use a battery of working memory tasks which aimed to isolate to Asperger syndrome in early-school-age children, (thereby removing the variables) were able to address these concerns and therefore it can be concluded there is a partial deficit in central executive.

ASD and Phonological Loop

The phonological loop is assumed to be responsible for the manipulation of speech based information  It may be extremely difficult to study ASD and its relationship with the phonological loop because, as was mentioned, the heterogeneity of ASD subjects. Differences in each ASD individual with how they utilize the spoken and written language is unique; yet often when considering working memory and the phonological loop, non ASD individuals show similarities in learning. In spite of this variability, language impairments include decreased communication, phonology, semantics, and syntax.  Fischbach et al (2013) conclude because of left-hemisphere brain deficits commonly found with ASD this may impact the ability of processing language. They add because of these deficits, compensatory effects in right hemisphere could lead to strengths in visuo-spatial processing (discussed below). While his compensation is important in that memory can adapt to brain disruptions, the challenge is that the left hemisphere does not advance functioning. It is important to note, as most research on ASD suggests, because of the changes in early development, phonological store is greatly impacted in reaction time among adolescents when studying speech in phonological short term memory (PSTM). Comparisons with typically developing (TD) subjects, the level of cognitive load during the phonological loop processing for ASD is significantly associated with reaction time and accuracy. This suggests perception of speech impacts access to speech.  Controversy remains with this assertion when Williams et al (2014) while studying visuo-spatial memory argue no association with impairment of verbal storage and ASD.

ASD and Visuo-Spatial Sketch Pad

In working memory, the visuo-spatial sketch pad is assumed to be responsible for manipulating visual images.  Prospective memory (PM) are highly prevalent in daily life and range from relatively simple tasks to extreme life-or-death situations. Examples include remembering to pick up milk at the grocery store after work or remembering to attach the safety harness when climbing buildings. This ability of the PM to remember to carry out a task (Williams et al, 2014) conclude that when considering time based tasks, ASD subjects because they show "diminished capacity have difficulty with processing visual storage", an important component of working memory and the visuo-spatial sketch pad (Sachse et al., 2013), when considering high functioning ASD (HFASD) such as Asperger syndrome while they did not find verbal memory impairment, conclude because visual motor information is impaired spatial working memory (SWM) "was impaired because of differences in cortical networks which led to higher number of working memory errors". Combining all aspects of working memory (central executive, phonological loop and visuo-spatial sketchpad), Because of the variability in ASD, researchers looked at various tasks specific to the working memory components with specific age populations (early school aged).  Because of matched IQ, HFASD had significant disadvantages around visuo-spatial sketchpad implicated by partial deficits in central executive.

Unlike ASD and working memory implications, ADHD has very different etiology on working memory.

Attention Deficit Hyperactivity Disorder and Working Memory

Figure 5.The above brainscan of brains shows the differences between adult with and without (Left) ADHD

People with ADHD usually accompany with some difficulties on their working memory, when we focus on the brain structure of the ADHD children, we could see that their brain structures are usually differ from children without ADHD, Several brain regions and structures, such as pre-frontal cortex, striatum, basal ganglia, and cerebellum tend to be smaller than people without ADHD. The overall brain size from ADHD children is generally 5% smaller than children without ADHD (Figure 5).These brain regions are closely related to how our working memory works, especially the pre-frontal cortex, thus with a smaller brain size, ADHD children’s working memory would perform poorly.

ADHD and Central Executive

The central executive seems equally impaired in both subtypes. A research used the Chessboard Task to test whether the subjects could maintain and reorganize visuospatial information, thus the Central Executive has been tested in this research. The result shown that ADHD children score lower than the normal students, nevertheless, the result of ADHD children improved when they received high level of reinforcement but not the control group .

In another research, the researchers used The Digits Backward, to test their capacity to store and manipulate information, and The Dual Task, to test their ability to coordinate two separate tasks. The result shown that ADHD children repeated fewer digits than the controls in The Digits Backward task and gain lower score in The Dual Task, these tasks show that central executive functions are critical for the variance in goal-setting skills in children with ADHD .

ADHD and Phonological Loop

ADHD children performed similarly in the Phonological loop tests with normal children, their score in The Digits Forward and The Word Recall tasks are similar. These tasks tested whether subjects could repeat the digits in a correct order. This result is consistent with the results of several earlier studies showing that deficits in the phonological loop are not characteristic of children with ADHD .

There is a research accompanied the ADHD children with Specific language impairment, also suggested that ADHD children have less impact in phonological loop. ADHD-C children with SLI scored significantly lower than those without SLI and normal children. Which support the hypothesis that Phonological loop are not the characteristic of ADHD children .

ADHD and Visuo-spatial Sketchpad

ADHD-I children and ADHD-C children who have motivational deficits, they have a destructive effect on their visuo-spatial working memory performance, according to The Chessboard Task, their score are lower than the control group . In Visuo-Spatial Test, it measures the ability to remember the number filled matrix, the result shown that children with ADHD performed more poorly than the control group . Nevertheless, High reinforcement can improve the working memory performance in both ADHD groups, but not the control group .

There are some minor differences between different subtypes ADHD. In the task of the Hopkins Verbal developmental Test–Revised (HVLT-R), The official Norwegian research versions, and the Brief Visuospatial Memory Test-Revised (BVMT-R), these tasks measure the performance of Auditory or verbal and visuospatial ability. The results shown that there are more impairment about developmental and delayed memory in the ADHD-I children when we compared the result with the ADHD-C children .

ADHD and ASD Developmental Implication

There are several behavioral strategies and treatments could help the ADHD patients, in order to improve their behaviors. For example a good and effective Classroom management could change the behavior of ADHD students,a more structured classroom, provide closer attention to students, and limitations of distractions could help to change the behavior of ADHD, these modifications may not have an effective assessment, but they usually included in the treatment plans. Some behavior therapies can be implemented to teachers and parents through some training programs, like Parent Management Training, Operant-conditioning usually involved in these programs, a positive reinforcement (consistent rewards for achieving goals and idea behavior) and positive punishment ( provide a negative consequence after the present of an undesired behavior). Teachers learn classroom Management as a technique to change behavior, Token economy ( student earns rewards when performing desired behaviors and loses the rewards when performing undesired behaviors), daily feedback and structured classroom activities

However,a research in 2013 shown that working memory training like the Cognitive training could only provide a short term improvements, and there are only little evidence that those improvements are permanent. Also in 2014, researchers analyzed that the current evidence for the accuracy of cognitive training for treatment of ADHD symptoms is not completed.

Glossary

Aural data – Data that is relating to or perceived by the ear.

Intellectual disability- A disability characterized by significant limitations in both intellectual functioning and in adaptive behavior, which covers many everyday social and practical skills. This disability originates before the age of 18.

Developmental disability- A diverse group of chronic conditions that are due to mental or physical impairments. 

Impaired language skills- A language disorder that delays the mastery of language skills in children who have no hearing loss or other developmental delays. 

Variability- How spread out or closely clustered a set of data is.

Impairments- In health, any loss or abnormality of physiological, psychological, or anatomical structure or function, whether permanent or temporary.

Mental retardation- A condition diagnosed before age 18, usually in infancy or prior to birth, that includes below-average general intellectual function, and a lack of the skills necessary for daily living. When onset occurs at age 18 or after, it is called dementia, which can coexist with an MR diagnosis.

Psychotic disorder- Severe mental disorders that cause abnormal thinking and perceptions. 

Executive dysfunction- A disruption to the efficacy of the executive functions, which is a group of cognitive processes that regulate, control, and manage other cognitive processes.

Cognitive load- the total amount of mental effort being used in the working memory.

Diagnostic Statistical Manual (DSM)- The standard classification of mental disorders used by mental health professionals in the United States. It is intended to be used in all clinical settings by clinicians of different theoretical orientations

Heterogeneity- A word that signifies diversity.

Pre-frontal cortex- The cerebral cortex which covers the front part of the frontal lobe. 

Striatum- Also known as the neostriatum or striate nucleus, is a subcortical part of the forebrain and a critical component of the reward system.

Basal ganglia- A group of structures linked to the thalamus in the base of the brain and involved in coordination of movement.

Cerebellum- The part of the brain at the back of the skull in vertebrates. Its function is to coordinate and regulate muscular activity.

Frontal cortex- Cortex of the frontal lobe of the cerebral hemisphere

Motivational deficits- Motivation is defined as the product of expectancies and values. 

Statistically significant-  The likelihood that a result or relationship is caused by something other than mere random chance. 

Executive functioning- A set of mental skills that help you get things done. These skills are controlled by an area of the brain called the frontal lobe.

Cortical-Consisting of cortex,the outer layer of the cerebrum.

Suggested Readings

Bruning, R. H., Schraw, G. J., & Norby, M. M. (2011). Cognitive psychology and instruction (5th edition). Boston, MA: Pearson.

Burt, B., & Gennaro, P. (2010). Behavior solutions for the inclusive classroom: a handy reference guide that explains behaviors associated with Autism, Asperger's ADHD, sensory processing and other special needs. Canada: The Donahue Group.

Eysenck, M. W., & Keane, M. T. (2001). Cognitive psychology (4th ed.). New York: Psychology Press.