Kohs Block Test

The Kohs block test, or Kohs block design test, is a cognitive spatial reasoning test originally designed for children or adults with a mental age between 3 and 19. It is mainly used to test persons with language or hearing handicaps, but also given to disadvantaged and non-English-speaking children. Subjects are tested on an individual basis; the test is not designed for administration to groups.

The test subject is shown a series of 17 cards with a variety of colored designs in order of increasing complexity and asked to reproduce them using a set of 16 colored cubes that measure an inch on all sides. Four sides of each cube are painted red, white, blue, or yellow, with the remaining two sides divided diagonally between red and white or blue and yellow. Scoring is based not just on the accuracy of the reproduction, but also on the number of moves the subject takes to complete the design. In addition, the examiner observes the subject's behavior during the test, including such factors as attention level, self criticism, and adaptive behavior (such as self-help, communication, and social skills).

The Kohs block test was widely used as a separate test up through the 1950s and 1960s, but by 2015 was more often included in such other tests as the Merrill-Palmer, Wechsler, and Arthur Performance scales. One reason is that the original version of the test is fairly time-consuming. Kohs' 1920 article specified time limits for each of the 17 designs, with 1.5 minutes for the first three tests up through 4 minutes each for the last four. It thus required a minimum of 45 minutes to administer the test and very often close to an hour. In 1942 a group of psychologists reported on a shorter version of the Kohs test suitable for use by the military in testing volunteers and draftees. The short form used a smaller number of Kohs' designs, but administered them in the order he had originally presented.

In the 1960s a version of the Kohs block test that could be used to test blind persons was devised by two psychologists working for the Vocational Rehabilitation Administration of what was then the federal Department of Health, Education, and Welfare. Known as the Stanford-Ohwaki-Kohs test, this version was rarely used as of 2015. A newer use of the Kohs block test is in evaluating the level of cognitive function in elderly adults or in patients recuperating from brain surgery; most of this research is conducted in Japan. Although the full Kohs block test is used less often than it was when it was first introduced, test kits and score cards for the test are still manufactured and distributed by the Stoelting Company in Illinois. The cost for the complete kit as of 2015 was $140.00.

See also Intelligence testing; Terman, Lewis.