This test measures the non-verbal memory span, as an approach to the visuospatial short-term memory (Milner, 1971). On the screen standard 9 green squares (version for adults) or rounds (version for children) can be seen. An increasing number of squares (starting with 2 squares) will turn into a blue color in succession. The aim is to click or tap the sequence in the same order. There are two trials of a certain series length. If at least one of the trials of a series length is correct, the series length of the next two trials becomes one element longer. This continues until the error criterion is reached, or until the maximum score (9 squares) has been reached. The block span is then defined as the series length that was still reproduced correctly. A “total score” is also calculated: the block span x the total number of correct reproductions. The green circles in the children’s version represent lily leaves in the water according to the adapted instruction. A frog jumps from one leave to the other and the child has to reproduce the route by clicking the leaves.
Other possible adjustments include the number of elements on the screen (max. 9) and the positions on the screen (random or fixed pattern). You can also choose from different fixed configurations of series, or have the series assembled randomly. Furthermore, the temporal aspects of a trial can also be adjusted (“flash time” and interval time), and the test can be set in such a way that 2 series of the same length must be correct (instead of 1) before the series becomes longer. There are 2 standard subtasks: A: block span forward, and B: block span backward.
In addition, there is an optional supraspan task. This last task consists of a number of trials with series length: Spanne score (forward) + 1, which was achieved in sub-task A. Also the first series is repeated in every 3rd trial. Scores are the total number of correct trials, and the number of correct trials of the repetitions. This last score is an extra measurement of working memory.
There are norms from healthy volunteers, as well as from left hemi sphere and right hemisphere patients (subtest A based on the original face-to-face test). In addition, there are norms from adolescents (subtest A and B, PC version), and from people with mild cognitive impairment.
An English language version is available.
Milner,B. (1971). Interhemispheric differences in the localization of psychological processes in man. British Medical bulletin, 27,272-277.