Adaptive behavior

Adaptive behaviors include life skills such as grooming, dressing, safety, food handling, working, money management, cleaning, making friends, social skills, and the personal responsibility expected of their age, social group and wealth group. These skills are typically split into three categories: conceptual, social and practical.^[1]

Adaptive behavior can be understood at both proximate and ultimate levels of explanation. At the ultimate level, it is thought to have evolved through natural selection, with major evolutionary approaches agreeing that humans possess psychological mechanisms that produce adaptive responses to environmental demands. ^[7] At the proximate level, adaptive behavior depends on intact cognitive processes, with research demonstrating that developmental changes in cognition are positively associated with changes in adaptive behavior in individuals with intellectual disability.^[8]

The term 'adaptive behavior' emerged in the 1800s in connection to defining intellectual disability (ID). It was sidelined with the use of IQ testing to determine ID, until the first half of the 20th century when it began to be incorporated into the definition of ID. In 1936 Doll developed the first assessment of the construct of adaptive behavior, the Vineland Social Maturity Scale (VSMS), and in 1941 he proposed that the definition of mental disability be revised to include measures of ability in the form of estimates of adaptive behavior, termed social competence.^[9][10]

This resulted in the American Association on Intellectual and Developmental Disabilities (AAIDD), formally including adaptive behavior deficits in their definition of ID in 1959, so that the definition then focused on both intellectual functioning and adaptive behavior, defined in 1961 as:

• The ability of an individual to maintain themselves independently
• The degree to which they meet the culturally imposed demand of personal and social responsibility^[10]

The concept of adaptive behavior is now widely used in the classification of developmental and intellectual disorder. It is one of the three criteria that must be met for a formal diagnosis of ID (alongside significant limitations in intellectual functioning and an onset before adulthood), as stated in the Diagnostic and Statistical Manual of Mental Disorders—Fifth Edition (DSM-5).^[10][11]

It is important to assess adaptive behavior not only because it can serve as a useful diagnostic tool but also because it provides information on how well an individual functions in daily life. It highlights both their strengths and weaknesses, enabling support plans to be created for individuals with intellectual disability, focusing on the areas where they need support.^[12]

In the past century a variety of scales intending to measure adaptive behavior have been developed, building on the VSMS. Some of the most notable ones (many of which have been revised at least once and are used often today) include:

• Vineland Adaptive Behavior Scale (Vineland ABS) (which built directly on the VSMS)^[10]
• American Association of Mental Deficiency-Adaptive Behavior Scale (AAMD-ABS)^[10]
• Adaptive Behavior Assessment System (ABAS)^[10]
• Diagnostic Adaptive Behavior Scale (DABS)^[13]

The different scales aim to measure different conceptual, social and practical skills, focusing on different domains depending on their context, target and purpose.^[12][13]

One problem with assessments of adaptive behavior is that a behavior that appears adaptive in the short run can be maladaptive in the long run and vice versa. For example, in the case of a group with rules that insist on drinking harmful amounts of alcohol both abstinence and moderate drinking (moderate as defined by actual health effects, not by socially constructed rules) may seem maladaptive if assessments are strictly short term, but an assessment that focuses on long-term survival would instead find that it was adaptive and that it was obedience under the drinking rule that was maladaptive. Such differences between short term effects and long-term effects in the context of harmful consequences of short-term compliance with destructive rules are argued by some researchers to show that assessments of adaptive behavior are not as unproblematic as is often assumed by psychiatry.^[14]

Adaptive behaviors can be learned and interventions can help increase the quality of life for those with intellectual disability, since adaptive behavior has been shown to be the main determinant of quality of life for individuals with intellectual disability.^[15] It is for this reason that training in adaptive behavior, whilst it is a key component of any educational program, is critically important for children with special needs. Interventions such as Early Intensive Behavioral Interventions (EIBI) which involve personalised teaching based on applied behavior analysis (ABA) have been shown to be successful in increasing adaptive behavior in individuals with autism spectrum disorder (ASD).^[16]

However, there are some difficulties when it comes to teaching adaptive behavior. Firstly there is significant heterogeneity within different intellectual disabilities, like ASD, but investigated interventions often focus on group-level effects, making it difficult to know which approach would best suit a specific individual's needs when it comes to teaching adaptive behavior.^[17] Additionally, studies have shown that parental attitudes, including an excessive reliance on assistants to perform tasks for their children, can act as significant barriers to teaching adaptive behavior.^[18]