Visualization From Projected Slides
Elton Watkins · JAMA · 1972
To the Editor.— I was delighted to read the scientific explanation by Packer and Robertson (221:1163,1972) concerning the visual acuity required to read projected slides. Many lecturers still seem to think that tabular data, suitable only for publication, can be used interchangeably as slide material. Some slides I have seen must have required definition in fractions of a minute of arc. The data might be discernible using high-powered binoculars in the front row if one had the time to assimilate all of it. Lecturers should recognize the entirely different requirements for comprehension of slide material contrasted to published tables. I hope that increasing use will be made of columns in various colors to code tabular data on simple slides. I have found a black background useful in this application. The difficulty with a white background relates to the quality of most of the electrical pointers made available to lecturers. They