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Intellectual Disability

The Intelligence Quotient (IQ) was first introduced by a French psychologist in an attempt to identify children with intellectual disabilities so that timely assistance could be provided. An IQ below 70 is now regarded as one of the diagnostic criteria for intellectual disability. The other defining characteristic of the condition is the demonstration of maladaptive behavior in everyday life. The disability may or may not be associated with a syndromal disorder, which can potentially be detected before birth. Screening for Down syndrome has thus become part of the standard antenatal care in a large number of countries. The screening offers women and/or their partners an opportunity to decide whether they should hold on to the pregnancy in the face of heavy odds of giving birth to highly dependent children. 

Mild intellectual disability may have subtle signs which only become apparent in adolescence whereas moderate or severe cases many a time manifest as developmental delays in early childhood. Child assessments conducted by professionals can pick up early issues, such as a failure to achieve milestones in motor skills and language development. Parents are also often able to notice that their kids have difficulty coping with activities of daily living, for instance, dressing, toileting, and feeding. Furthermore, it is hard for them to engage in meaningful social situations or ordinary school curricula. It is of paramount importance to seek timely help from experts since a whole lot of conditions can mimic the presentation of intellectual disability and each of them warrants different interventions. A common differential diagnosis is autism spectrum disorder, which sometimes coexists with intellectual disability.

There are innumerable organizations devoted to provision of specialized aids and services to the intellectually disabled. The condition is potentially amenable to therapies which adopt psychological, social, behavioral, cognitive, and family approaches. It is shown that better outcomes are usually observed in cases where interventions are prescribed early. A wide range of social enterprises aim to employ the more sociable individuals so that they can interact with people from all walks of life in relatively safe environments, thereby alleviating stigma. Those who are less able to adapt to changes can still find job opportunities in workshops. Rehabilitative programs are in place to equip them with the skills to take care of themselves. Staffed residences are available for those who need constant attendance in order to prevent bodily harm to themselves or others. Family members can also benefit from dedicated support as it could be stressful to empower dependents to live to the fullest.

High IQ Societies

Mensa is the high Intelligence Quotient (IQ) society that has the longest history and most members. An individual must be among the top 2% of a population as evidenced by a recognized intelligence assessment in order to be eligible for joining the society, which is governed by nearly 50 domestic divisions. Approximately 200 testing tools have been accredited by the division in the United States but the tests have to be conducted in regulated environments where no online systems are permitted. The 5th edition of the Stanford-Binet Intelligence Scale and the 4th edition of Wechsler Adult Intelligence Scale, which are discussed in other entries of this blog, are notably two of the tests that satisfy Mensa requirements. 

A high IQ is the sole eligibility criterion so diverse demographics in terms of age, gender, ethnicity, occupation and social status are treated in the same manner, hence the Latin name Mensa, which literally means a round table. The members can interact with each other on formal as well as informal occasions for the common good and for directing efforts towards promotion of intelligence on both personal and societal levels. One might be surprised by the fact that IQ can be completely independent of academic achievements; failures at schools should therefore never stop anybody from taking an IQ test. Every member can have a voice in virtually all topics but there is no need for a consensus – it is in fact barely possible to reach one given the often strong opinions. 

It might be difficult to convince ordinary people that Mensa’s popularity is in part due to the relatively lenient cutoff IQ for eligibility. The Mega Society, in stark contrast to Mensa, genuinely targets the cream of the crop – the top millionth of a population with regard to intelligence – whilst only 26 individuals have been granted membership to date. The Titan Test is currently the only assessment tool accepted by the Mega Society as former test materials have been leaked for illicit purposes. In spite of the exceptionally difficult access to the society, journal articles have been irregularly issued so that the general public can have a better idea about the elites’ perspectives. 

A handful of entities lie between Mensa and the Mega Society in terms of size and cutoff IQ. In theory, one in every 30,000 people is entitled to the membership of the Prometheus Society, which is named after the Greek mythical hero known for his intelligence. The journal is exclusive to the members and subscribers so it is arguably less transparent than the Mega Society’s. The Triple Nine Society is named as such since it recruits individuals who fall within the top 99.9th percentile. It encourages exchanges of information among the members by means of online platforms. 

The Wechsler Model

David Wechsler, an American psychologist, defined intelligence as the ability to carry out rational mental processes, to perform actions on purpose, and to interact with surroundings logically. Keeping the elements in mind, he was able to pinpoint a number of drawbacks of Alfred Binet’s Intelligence Quotient (IQ) test, which was the prototype for similar assessment tools. He made respective modifications and published the first version of Wechsler Adult Intelligence Scale (WAIS) in 1955. He appreciated the factors which were irrelevant to intelligence but could potentially affect the examination results, such as a test taker’s nervousness and reading speed. The test assessed separate aspects of intelligence and then generated overall scores, in contrast with Binet’s single score, by taking interdependence into account.

WAIS has evolved over time and the fourth edition has become the most widely recognized and administered instrument for measuring an individual’s IQ, in spite of criticisms about the deviations from Wechsler’s original ideations. There are a total of four test domains, which consist of a certain number of core and supplemental tests as shown below. 

Verbal Comprehension

  • Similarities – The subject has to point out in what way a word can be likened to another.
  • Vocabulary – The nominal capacity is evaluated by showing illustrations to the subject.
  • Information – Knowledge which is perceived to be commonly accepted is tested.
  • Comprehension – Social scenarios which are frequently encountered in everyday life are simulated. 

Perceptual Reasoning

  • Block Design – The subject is asked to reconstruct and mimic an illustration or model as closely as possible by making use of blocks.
  • Matrix Reasoning – The subject is presented with a matrix and the task is to extend the sequence in a sensible manner.
  • Visual Puzzles – The subject has to pick one among three choices so that the presented puzzle can be reproduced. 
  • Figure Weights – A weight has to be chosen in an attempt to balance a scale. 
  • Picture Completion – The subject has to deduce the omitted component(s) within an illustration(s).

Working Memory

  • Digit Span – A series of numbers are enunciated and the subject has to repeat them in a forward or backward order with or without further arrangements as instructed.
  • Arithmetic – The subject has to tackle mathematical questions by means of unvoiced calculations.
  • Letter-Number Sequencing – A sequence of characters and digits are enunciated and the subject has to repeat them in alphabetical or ascending order.

Processing Speed

  • Coding – Given a printed key, the subject has to replicate symbols which correspond to assigned numerals. 
  • Symbol Search – Having been presented with a collection of symbols, the subject is asked to determine if any of the symbols in the second collection is duplicated. 
  • Cancellation – The subject has to cross out specific shapes out of a set. 

An average person is expected to score 100 points on WAIS.

The development of Intelligence Quotient

As education became compulsory in France in the early 20th century, the Intelligence Quotient (IQ) was invented by Alfred Binet, a native psychologist, in an attempt to stratify students and to offer extra assistance to the disadvantaged. Some believed that they might benefit from interventions early in their lives so they could be spared settlement in asylums. The IQ test was composed of questions which assessed a variety of skill sets, for instance, attention, memory, and problem-solving. These were not conventionally taught at schools but were perceived to be the most accurate methods of anticipating the pupils’ achievements. According to Binet’s model, intelligence would change with age rather than remain static since birth. In addition to chronological age, he therefore introduced the principle of mental age, by which individual abilities were compared with the average scores of specific age groups. Nonetheless, he was still critical of his own testing system, which failed to take plenty of confounding variables into consideration or to address the multifactorial nature of intelligence, hence compromised generalizability.

Numerous examination tools have been developed since Binet’s endeavor. In 1916, Lewis Terman, a psychologist at Stanford University, modified Binet’s IQ test by studying a number of Americans and issued a version that corrected the original flaws and was widely recognized across the nation. The resultant Stanford-Binet IQ test has been able to spot the intellectually advanced instead of solely focusing on the lower end of the spectrum, and has further gained popularity with subsequent revisions and validations. The United States Armed Forces made use of the Army Alpha and Beta tests, which were created by another psychologist Robert Yerkes, for better appointments with regard to the capacities of the newly joined during World War I. The former was a written test, whereas the latter was devised to overcome the effects of illiteracy and language barriers. The high scorers were trained as officers while their low counterparts were discharged from the military. It was a milestone as the application of IQ measurement went beyond academic reasons. 

In the middle of the last century, David Wechsler presented the novel and prominent Wechsler Adult Intelligence Scale (WAIS) to the world by making improvements to Binet’s prototype. Besides WAIS, the Wechsler Intelligence Scale for Children (WISC) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) were specially designed for young persons. The Wechsler scales have become the most frequently used assessment tools to date and the bases on which several other testing systems have been developed.