Implicit memory tests seem to tap a very different set of memory processes than do explicit memory tests. In a 1992 experiment, subjects were shown a series of words and asked to pay attention either to the words’ physical appearance (letter shapes) or to their meaning. In a later task, the subjects were asked to complete word stems (such as ele_____). Some subjects believed the task was unrelated to the previously studied words and were told to complete the fragment with the first word that came to mind. Others knew that the fragments were clues from the previously studied words. Surprisingly, whether people paid attention to the words' appearance or meaning—a variable that greatly influenced people's explicit memory test performance—had no effect on implicit memory test performance.