**Corsi Blocks Tapping Test (testcode: CORSI)**

This test measures the nonverbal memory span, as an approximation of the visuospatial short-term memory (Milner, 1971). Standard nine green squares (adult version) or circles (version for children, see figure) can be seen on the screen. An increasing number of squares (starting with 2), in succession, is turned into a blue color for a short period. The intention is to click the sequence in the same order using the mouse. There are two (standard) presentations (trials) of a series of a certain length. If at least one of the trials of a series with a certain length is correct, the length of the next two series is 1 element longer. This continues until the error criterion is reached or until the maximum score is achieved. The resulting block span is the length of the longest series that has been correctly reproduced. Also, a “score” is calculated: the block span x the total number of correct reproductions. The green circles in the children’s version represent water lily leaves according to the modified instruction. A frog jumps from leaf to leaf and the child must click the leaves in the required order.

There are three possible sub-tasks: A. block span forward; B. block span backward; C. supra-span task. The final task consists of a series of trials with length: block span-forward + 1. Also, the first series is repeated at every third trial. Scores here are the total number of correct trials, and the number of correct trials on repetitions. The final score is another measure of working memory.

Other possible test parameters include among others the number of elements on the screen (max 9) and the positions on the screen (random or fixed pattern). One can also choose from different configurations of fixed sequences, or have the series put together randomly. Furthermore, the temporal aspects of trials can also be modified (“flash time” and interval time), and the test can be adapted such that two series of the same length should be correct (instead of 1) before the series length gets larger. Finally, for subtask C the number of trials can be adapted, and the pattern of repeated sequences (every third, every fourth, etc.). There are norms from healthy volunteers, as well as from patients with left and right hemisphere damage (subtest A, based on the original face-to-face test). There are also norms of adolescents (subtest A and B, pc version).

References:

Milner,B. (1971). Interhemispheric differences in the localization of psychological processes in man. *British Medical bulletin, 27,*272-277.