A quick note on terminology: many of this is subjective. Every person and family has their own language preferences, and while I’ve compiled information based on some of the most common trends, it is always best to ask individuals what they prefer!


The difference between “learning,” “developmental,” and “cognitive” differences:

Cognitive and developmental differences tend to fall into two separate categories, while learning differences tend to encompass elements of the other two. One easy way to differentiate between the three is age of diagnosis: developmental disabilities can be diagnosed in very early childhood, while learning disabilities are generally diagnosed between the age of five and adulthood, and cognitive disabilities can be diagnosed at any age.


Cognitive Differences:


The term “cognitive differences” is commonly used to refer to IQ. People with cognitive differences often take longer to complete academic tasks than people with typical cognitive function and can have difficulty focusing. Cognitive differences can be identified at any age (dementia is an example of a cognitive difference that is not diagnosed until old age).


Developmental Differences:


The term “developmental differences” refers only to conditions diagnosed before the age of 22. Developmental differences are measured by difficulty meeting developmental milestones (e.g. age of talking, writing, etc.).


Learning Disabilities:


The term “learning disabilities” refers to conditions that are diagnosed before adulthood and measured by IQ. Learning disabilities can often encompass both developmental and cognitive differences, and often result in atypical academic achievement. They are diagnosed based on an IQ test and another test (Vineland Adaptive Behaviour Scale-II) that measures communication, daily living skills, socialization, motor skills, and maladaptive behavior Index.


The DSM-V defines learning disabilities as having three main characteristics:


  1. diagnosed before adulthood
  2. significantly reduced ability to understand new or complex information and learn new skills
  3. impaired social functioning (difficulty coping individually as a member of society)


Categorization of Learning Disabilities: PMLD, SLD, MLD, SpLD


The different types of learning disabilities, Profound and Multiple Learning Disabilities (PMLD), Severe Learning Disabilities (SLD), Mild Learning Disabilities (MLD), and Specific Learning Disabilities (SpLD) are commonly categorized in two different ways, one according to scale and one to criteria.


Scale Model:



The types of learning disabilities are organized by severity:


PMLD “Profound” > SLD “Severe” > MLD “Mild”



"Profound" refers specifically to an IQ under 20. People with profound difficulties often have mobility difficulties and complex health needs. Many are non-verbal.




"Severe" refers specifically to an IQ under 70. People with severe difficulties often need assistance with everyday tasks and have limited verbal communication (more than people with profound difficulties).



"Mild" refers to people who do not need assistance with everyday tasks but may have difficulty with complex/analytical thought.




Criteria Model:



"Severe Learning Disability (SLD)" refers mostly to IQ-- to cognitive/"intellectual" impairments.  People with SLDs often also have difficulty with mobility, communication, and acquisition of self-help skills. The learning disabilities also span all subjects in school (people with "Specific disabilities" may have difficulty grasping a single subject-- dyslexia is a good example of a specific disability).


"PMLD" refers to people with SLDs who also have a range of other disabilities-- medical conditions, sensory impairments, etc. Most of these people require a high level of support, both for learning and personal care. The main criterion for PMLD is having more than one disability.



"Complex disability" refers to people with more than one disability who may or may not have a learning disability. So PMLD encompasses both SLD and complex disabilities, but a person with an SLD or complex disabilities does not necessarily have PMLD.



Autism Spectrum Conditions:



"Autism Spectrum Condition" refers to a specific neurodevelopmental diagnosis that includes:



  1. restrictive/repetitive (or niche) behavior, interests, and activities
  2. difficulty with social interaction and communication
  3. [heightened or dull sensitivity to sensory experiences]-- the other two are the main ones, but this is relevant to Seesaw!



This definition is constantly evolving. It used to encompass four separate conditions-- autistic disorder, Asperger's disorder, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified (PDD-NOS)-- but now labels them all "ASCs." This definition doesn't include the cognitive/intellectual components of learning disabilities.



“Condition” vs. “Disorder” vs. “Difference” vs. “Disability”


The language around ASCs is also constantly evolving. The word “condition” in Autism Spectrum Condition was added recently, to replace “disorder.” The change was an effort to emphasize the difficulties associated with developmental differences in a world that has been slow to accommodate them-- as “difference” does not fully--while maintaining that ASCs are not deficits but simply forms of neurodiversity-- as “disorder” and “disability” fail to do. While “Autism Spectrum Condition” has become the official term, language around ASCs is still subjective, and many people in the ASC community prefer certain terms over others.


As you probably noticed above, official documentation is slow to catch up with colloquial language chance. “Disability” is still widely used in clinical practice (“learning disability” is an official term, as are PMLD, SLD, SpLD, and MLD). “Difference” is slowly becoming the norm when describing cognitive and developmental processes.



“High-functioning” vs. “Low-functioning”


These are terms that are used to differentiate between people with ASCs or other disabilities-- most often on the basis of language acquisition and IQ (above or below 80). While these terms are used in clinical practice, many families find them unspecific and prefer not to use them. While there is no official definition, generally, individuals with “low-functioning” ASCs are (compared to those with “high-functioning ASCs) unable to complete daily tasks without assistance, less likely to speak, more likely to have epilepsy, more likely to have memory problems, more likely to engage in repetitive behavior, and generally have IQs under 80. Many of these qualities are both complicated and subjective, and it is often difficult to classify people based on the criteria-- this is why, as mentioned above, most families prefer to refer to specific qualities (such as speech or IQ) rather than grouping a complicated web of scaled criteria into “high-functioning” or “low-functioning.”


Further Reading:

Terminology guide (learning disabilities)

New terminology criteria


Complex Care Definitions