The General Intelligence Assessment (GIA) provides an accurate prediction of the time it will take someone to get to grips with a new role/regime. By gauging their capabilities, you will be able to keep your people engaged in their work and your organisation with appropriate challenges suited to their strengths. The GIA will also enable you to identify potential leaders, those that can think on their feet and the people better suited to methodical problem solving.

OverviewThe Science

Assess: Aptitude and ability
Type: Normative psychometric assessment
Time: 50 minutes

GIA gives you a prediction of a person's potential to grasp a new role or respond to training. It will help you to identify your high flyers and future leaders and give you the tools to understand how to develop them through training.


Use GIA to:

  • Measure mental capacity, including problem solving and adaptability
  • Understand how to develop through training
  • Identify potential leaders who have the skills to drive change
  • Ensure a person is sufficiently challenged

Want to see it in action? Check out our Opus Energy testimonial.

Test author: Professor Sidney Irvine
Year of construction: 1992

Background and theory:

Professor Sidney Irvine graduated with an MA Medicine from Aberdeen University. His Ph.D. was supervised by Professor Alec Rodger, the Head of Occupational Psychology at Birkbeck College. As Professor of Differential Psychology from 1979 at the University of Plymouth, he established the Human Assessment Laboratory. With his colleagues in the unit he devised The British Army Recruit Battery (BARB). Later on the BARB was developed into The Navy Personnel Series (NPS).

The General Intelligence Assessment (GIA) was based on the NPS because the Navy tests were all paper-and-pencil based and had undergone a comprehensive and exhaustive research validation programme. The TST is a measure of the fluid intelligence component of cognitive ability as measured by five constituent test elements: Reasoning, Perceptual Speed, Number Speed and Accuracy, Spatial Visualisation and Working Memory. Thomas integrated the GIA into its product suite in 1993.

Intelligence has been defined as having fluid and crystallised components (Horn & Cattell, 1966):

  • Fluid Intelligence (pure processing speed) – basic intellectual processes of manipulating abstract concepts, generalisations and logical relationships (Carroll, 1993). Fluid intelligence is used to solve new problems, use logic in new situations and identify patterns.
  • Crystallised Intelligence (learnt factors) –verbal, mechanical, and numerical ability etc. Crystallised intelligence is the ability to use learned knowledge and experience

The GIA looks at an individual's speed of processing information and ability to learn and develop new skills. The assessment is used for a variety of purposes: recruitment, retention, development, management, identifying training needs, career guidance, succession planning and benchmarking.


The Thomas GIA is a timed, paper-and-pencil, multiple-choice aptitude assessment. There is a time limit and maximum number of items for each test: Reasoning – 50 items, time allowed: 4 minutes; Perceptual Speed – 60 items, time allowed: 3 minutes; Number Speed and Accuracy – 60 items, time allowed: 4 minutes; Spatial Visualisation – 60 items, time allowed: 5 minutes; Working Memory – 72 items, time allowed: 4 minutes.

The GIA is a normative assessment. Individuals are presented with their results compared to that of a comparison population. Although the overall score measures ‘trainability’, each of the five tests measures a specific cognitive function (detailed below):

Perceptual Speed: This test measures the perception of inaccuracies in written material, numbers and diagrams, the ability to ignore irrelevant information, the ability to recognise similarities and differences, and error checking. It tests the speed of semantic encoding and comparison.

Reasoning: This test measures the ability to make inferences, the ability to reason from information provided and to draw the correct conclusions. This test assesses the ability of an individual to hold information in their short-term memory and solve problems.

Number Speed and Accuracy: This is a test of numerical manipulation and a measure of basic numerical reasoning ability. It measures the degree to which an individual can work comfortably with quantitative concepts.

Spatial Visualisation: This test measures the ability to create and manipulate mental images of objects. This test correlates with tests of mechanical reasoning, and assesses an individual’s ability to use mental visualisation skills to compare shapes. It relates to the ability to work in environments where visualisation skills are required to understand and execute tasks.

Working Memory: This test measures the ability to hold information that has been previously processed, while simultaneously process and assimilating incoming information. It is a test that makes demands on reconstructive memory processes.

Reliability and validity:

The GIA was rigorously validated within the BARB and NPS development phases and has been shown to be a reliable and valid measure of cognitive ability. For more information on validity and reliability studies, please see Collis, J.M. and Irvine, S.H. (2006). GIA Series. The General Intelligence Assessment . Technical Handbook, Thomas International Ltd., Marlow.