# Attention and Iconic Memory **Opening (not a real abstract):** The extent of our “span of our apprehension” is one of the oldest questions in philosophical psychology, with roots going back to antiquity.1 As experimental psychology flourished toward the end of the 19th century, investigators sought to gain experimental purchase on the question. Thus, in 1886, Cattell conducted a pioneering investigation which he took to settle the matter (under the relevant experimental conditions). Cattell (1886) employed a “gravity chronometer” to present subjects with a series of letters for about 1 ms. After presentation, observers were able to recall at most three to five letters from such displays, irrespective of how many characters were presented, a finding later confirmed by Sperling (1960). Unfortunately, Cattell’s experiment did not settle the matter.2 His experiment speaks directly only to the following question: (1) How much **Authors:** [[Philosophical and Psychological Essays]]