Titles of transparencies used in the talk: 1. Spans of Mental Activities 2. Measures of Absolute Judgement 3. Measures of Span of Immediate Recall 4. Elementary Digraph 5. Elementary Digraph with Associations 6. Digraph with Five Vertices 7. Lattice of Partitions on a 3-element Set 8. Lattice of Subsets of a 3-element Set 9. Levels in the Lattice of Subsets 10. Selected Values of PI (n, k) 11. Selected Values of PI (n, k) (same as transparency # 10, except bigger scale and better, clearer figures, easier to read). 12a. Inner Cycle of 19 Members for Pascal Syntax 12b. Inner Cycle of 19 Members for Pascal Syntax (same as transparency # 12a, except bigger scale and better, clearer figures, easier to read). Please click here “The Magical Number Three--Plus or Minus Zero.” for a link to the article for which these transparencies were displayed.