In Brook's Influential Working Memory Task, Subjects Were Instructed to Hold

In Brook's influential working memory task, subjects were instructed to hold a visual image of a large "F" in mind. When asked to visually scan the image clockwise and report the location of the corners:

A) It was very difficult to verbally report the locations.
B) It was very difficult to locate the correct answer on a separate printed page.
C) Subjects found they were unable to visually scan the image, regardless of the secondary task.
D) Subjects could easily report the locations of the task regardless of what else they were doing.