The Leiter-3 is a tool designed to assess non-verbal intelligence, nonverbal memory and attention.

The Leiter-3 includes:

• Cognitive Scales made up of five tests: Figure-Ground, Form Completion, Classification and Analogies, Sequential Order  and Matching/Repeated Patterns (an additional optional test);
• Attention and Memory Scales made up of another five tests: Attention Sustained, Memory Forward, Memory Reversed, Non-verbal Stroop Test  and Attention Divided (an additional optional test).

The Leiter-3 is based on the hierarchical theory of intelligence by Cattell, Horn and Carroll.

The Leiter-3 is the only test which is entirely nonverbal. The examination is carried out without words which makes the test applicable for children with whom verbal communication is difficult or impossible.

The Leiter-3 is a new version of Leiter Scale  already well known in Poland. Compared with the earlier version it allows to assess not only non-verbal intelligence but also attention and memory. It provides three composite indices: the Nonverbal Intelligence Quotient together with the Nonverbal Memory and Proceeding Speed Quotients. Subtest scores can also be interpreted which allow to evaluate reasoning abilities, eye perception, sustaining and dividing attention and also short term eye memory, working memory and ability to cope with interference.

Test scores together with the Nonverbal Intelligence and Nonverbal Memory Quotients may be expressed as Development Scores. The Leiter-3 is one few tests which allow to use Development Scores as well as to follow advances in cognitive abilities related to age or specific educational interventions. The Development Scores are susceptible of even minor changes which occur within the development process but which cannot affect the IQ. The Development Scores scale allows to evaluate effectiveness of therapy or development stimulating interventions as well as to observe development delays or regressive changes occuring with certain disorders or diseases.

The evident advantage of the Leiter-3 lies in the fact that it includes the Observation Scale. The scale was developped to detect non-typical behaviour features which can negatively affect child's functioning, that is, may create difficulties at school or in the sphere of social relations. The evaluation concerns the following dimensions: Attention, Impulse Organization and Control, Level of Activities, Gregariousness, Energy and Feelings, Self-regulation and Mood Regulation, Uneasiness and Sensual Reactivity.

In the standardization process the inferential norming procedure was applied based on the so-called continuous standardization method. The norms were developed for 44 groups from among general population (1 705 respondents) and for 40 groups from among the population of children with severe auditory impairement (576 respondents).

Calculated test scores are expressed on a 21-points scale where M  = 10 and SD  = 3. Composite scores are expressed on a scale of „Wechslerian” quotients where M  = 100 and SD  = 15. The range of the Nonverbal Intelligence Quotient is 30–170 and that of the Nonverbal Memory and Proceeding Speed Quotients is 45–155.

The complete set of materials includes the Polish version of a video presenting the Leiter-3 scale, its main features and examination procedures for all tests.

Materials: 

• The complete set (aids in a bag, 25 test booklets, 25 transcript sheets, 2 kinds of score sheets 25 copies each, 3 manuals)
• Original manual
• Manual for the Polish standardized version (age: 3–20)
• Tables of norms (age: 3–20)
• Manual Standardization for adults (age: 21–75+)*
• Test tools in a bag
• Test booklet (25 copies)
• Transcript sheets for both scales (25 copies)
• Transcript sheets Nonverbal Intelligence (25 copies)**
• Development score sheets for children with severe auditory impairment (25 copies)
• Development score sheets for general population (25 copies)