The Wiesen Test of Mechanical Aptitude is a 60-question, 30-minute test of how easily you learn to use and maintain machines. See format, scoring, and prep.
Dr. Russell T. WarneChief Scientist
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The Wiesen Test of Mechanical Aptitude (WTMA) is a 60-question, 30-minute multiple-choice test that measures a person's ability to learn to use and maintain equipment and machinery. It was developed by Joel P. Wiesen, PhD, is published in paper form by Psychological Assessment Resources (PAR), and has been offered online by Criteria Corp since 2007. Its signature feature is the item content: pictures of everyday objects, written at a sixth-grade reading level, chosen deliberately to reduce gender and ethnic bias relative to older mechanical tests. This article covers what the WTMA measures, its format and scoring, the bias-reduction design, and how to prepare.
What the WTMA measures
Criteria describes the WTMA as measuring "mechanical aptitude, or ability to learn to use and maintain equipment and machinery," and as predicting performance in occupations that involve operating, maintaining, and servicing tools, equipment, and machinery. It is one of the three big names in the format, alongside the Bennett and the Ramsay MAT; our guide to what a mechanical aptitude test is covers the family as a whole.
The content spans broad physical concepts: basic machines, movement, gravity and center of gravity, basic electricity and electronics, heat transfer, and basic physical properties, all asked through common physical objects, tools, and devices. A published sample item shows two pitchers of ice water and asks, "Which pitcher of water will stay colder longer?" with the options A, B, and "There is no difference." Everyday physics, no shop jargon. An item like that is easy to read and hard to fake: either you can reason about heat transfer from ordinary experience or you cannot.
Format, scoring, and administration
• Length and timing: 60 multiple-choice picture questions, with an estimated time of 30 minutes.
• Reading level: Written at a sixth-grade reading level; a Spanish version is available.
• Paper or online: PAR publishes the print WTMA PAR Edition for ages 18 to 65, administered with a stopwatch. Criteria Corp has offered the test online since licensing it from PAR in October 2007.
• Scoring: The online version reports a raw score (questions answered correctly) plus a "percentile rank," the share of test takers whose scores fall at or below yours, with instant score reports. In Criteria's worked example, a raw score of 45 corresponds to the 66th percentile.
A test designed to reduce bias
The WTMA's origin story is corrective: Criteria states it "was specifically developed to improve upon shortcomings of earlier mechanical aptitude tests." PAR states the test was "designed to minimize academic, gender, and ethnic bias," avoiding questions that require familiarity with objects or events found only in specific locales. Criteria likewise reports that the content was written to minimize gender and racial or ethnic bias, and that the test shows lower adverse impact than older mechanical aptitude tests.
The distributor publishes a head-to-head comparison. According to studies summarized by Criteria, four studies comparing the WTMA with the Bennett Mechanical Comprehension Test found the WTMA showed less adverse impact on women, with the average male-female score difference 0.31 standard deviation units smaller on the WTMA.
The nuance worth keeping is that the reduced-bias design changes the content vehicle, swapping shop-specific hardware for everyday objects, while the underlying construct stays put. That is why the WTMA still correlates .70 to .80 with the older mechanical tests it was built to improve on.
How the WTMA relates to IQ
Criteria reports construct validity correlations of .70 to .80 with comparable mechanical tests, and Ramsay Corporation independently reports a correlation of .72 between the WTMA and its own Ramsay Mechanical Aptitude Test. For prediction of actual work, Criteria cites a criterion validity coefficient of .24 in a carpet-manufacturing study, reports high reliability for the test, and describes a machine-operator case study in which high scorers were much more likely to receive a high performance rating from a manager.
Mechanical aptitude is one narrow ability within the Cattell-Horn-Carroll model of intelligence, correlated with general cognitive ability but far from the whole profile. Selection research from Schmidt and Hunter through Sackett and colleagues finds cognitive ability among the strongest predictors of job and training performance, and a fuller battery samples more of it. The RIOT IQ test (the Reasoning and Intelligence Online Test) is built on that model and measures six indices (Fluid Reasoning, Verbal Reasoning, Spatial Ability, Working Memory, Processing Speed, and Reaction Time); the versions are compared at riotiq.com/assessments.
Who uses it, and how to prepare
Criteria lists its top positions for the WTMA as machine operators, electricians, construction workers, field service technicians, and mechanics. The test is used in employment selection and training programs in manufacturing and industrial settings, and PAR also licenses it for academic research. Criteria offers the online version in every geography it serves except Asia-Pacific.
Preparation follows the general rule for cognitive tests. A meta-analysis of 107 samples and 134,436 participants found retesting raises scores by an adjusted average of .26 standard deviations, with larger gains from coaching or identical forms. For the WTMA specifically, the useful work looks like this.
• Refresh everyday physics: Heat transfer, center of gravity, simple machines, and basic circuits cover most of the conceptual territory.
• Practice the pace: 60 items in about 30 minutes leaves roughly 30 seconds per question, so keep moving and return to hard items at the end.
• Skip the vocabulary drills: Because items use household situations at a sixth-grade reading level, preparation is less about words and more about physical reasoning.
A WTMA score describes how readily you learn to work with machines. To see that ability in the context of a full cognitive profile, the RIOT IQ test at riotiq.com measures six indices and publishes a margin of error for every version.
Frequently asked questions
How many questions are on the Wiesen test?
The WTMA has 60 multiple-choice picture questions with an estimated time of 30 minutes, available on paper through PAR or online through Criteria Corp.
Do I need trade experience to take the WTMA?
No. Items use common household objects rather than trade-specific hardware and are written at a sixth-grade reading level, so candidates without shop backgrounds are not penalized.
How is the WTMA different from the Bennett?
The WTMA was built specifically to improve on older mechanical aptitude tests, and distributor-summarized studies report smaller male-female score gaps than the Bennett. The two still correlate strongly, so they measure much the same underlying ability.
Where do you take the WTMA?
Through an employer or program that administers it: PAR's paper edition is given in person with a stopwatch, and Criteria's online version delivers instant score reports.
References
1. Criteria Corp. (n.d.). Wiesen Test of Mechanical Aptitude (WTMA) [product page]. criteriacorp.com
2. Criteria Corp. (2023). WTMA: Wiesen Test of Mechanical Aptitude [overview]. criteriacorp.com
3. Criteria Corp. (2007, October 18). Criteria adds WTMA, leading mechanical aptitude test, to HireSelect [press release]. criteriacorp.com
4. Hausknecht, J. P., Halpert, J. A., Di Paolo, N. T., & Moriarty Gerrard, M. O. (2007). Retesting in selection: A meta-analysis of coaching and practice effects for tests of cognitive ability. Journal of Applied Psychology, 92(2), 373-385. doi.org/10.1037/0021-9010.92.2.373
5. Psychological Assessment Resources. (n.d.). Wiesen Test of Mechanical Aptitude PAR Edition. parinc.com
6. Sackett, P. R., Zhang, C., Berry, C. M., & Lievens, F. (2022). Revisiting meta-analytic estimates of validity in personnel selection. Journal of Applied Psychology, 107(11), 2040-2068. doi.org/10.1037/apl0000994
7. Schmidt, F. L., & Hunter, J. E. (1998). The validity and utility of selection methods in personnel psychology: Practical and theoretical implications of 85 years of research findings. Psychological Bulletin, 124(2), 262-274. doi.org/10.1037/0033-2909.124.2.262
