Spatial visualization: running visualization for empty squares

A technique is reported in which an oral description of empty squares had to be visualized. A tone signaled completion, and a response was made whether the last square had touched a previous square. The chain lengths varied from 10 to 19 squares at closure. Local closure sizes consisted of 4 to 10 squares. Closures up to 6 squares produced the least errors. There were biases in response as a function of response type and chain length. The technique could be useful for monitoring continuous spatial visualization.