Persuasive Advertising - J. Scott Armstrong [179]
9.4.3. Use columns for long informative text
Ivory Soap used two-column ads as far back as 1883. Long lines make it harder for readers, especially poor ones, to traverse back to the next line. Very short lines are inefficient as they do not allow readers to capture as many characters per eye fixation. The optimal length for reading a print ad is about 50 characters per line, and for computer screens about 55. This is not a firm rule as line lengths between 20 and 70 characters are acceptable.
When setting columns in a word processing program, it can be helpful to adjust character spacing.
Evidence on the effects of columns
Lab experiments—two for print and three for computer screens—supported the above optimal line lengths of 50 characters for print and 55 for on-screen (summarized in Dyson and Haselgrove 2001).
Our analysis of quasi-experimental data supports the use of columns:
Print ads using columns for long copy had higher recall. Our WAPB analysis found 25 pairs of ads with long copy (i.e., containing 100 or more words) in which one ad used columns, while the other ad did not. Recall for the ads using columns was 1.08 times better than for the other ads.
There is some uncertainty about the optimum width of columns. Eight studies of line lengths on computer screens concluded that reading ease, speed, and accuracy of subjects were better when length lines were approximately 70 characters per line (Bernard, Fernandez, and Hull 2002).
In Wheildon (1995, p. 125), 38 percent of his subjects said it was difficult to read body type in columns that were more than 60 characters wide. At the other extreme, 87 percent said it was difficult to read columns with fewer than 20 characters.
9.4.4. Consider blank line spacing between paragraphs for scannability
Benjamin Franklin was apparently the first printer to break up blocks of text with blank space (Goodrum and Dalrymple 1990). Prior to that, advertisers did not want to “waste” space.
White (or blank) space helps guide the eye to key parts of an ad. Put white space before and after key points to emphasize them.
Blank-line spacing between paragraphs makes the text easier to scan than with first-line indents. However, blank-line spacing is less relevant for high-involvement products with strong arguments because advertisers want to encourage readers to read rather than to scan. Blank lines might be disruptive to readers as if to alert them to a shift in topic.
Websites use blank-line spacing. In July 2006, we examined a sample of 100 popular websites and found that all used blank-line spacing. In contrast, to encourage reading rather than scanning, the vast majority of books use first-line indent rather than blank-line spacing.
In 2006, we examined 164 full-page (and two-page) ads in The Economist, Kiplinger’s Personal Finance, and Ladies Home Journal. Of these, 94 percent used blank-line spacing, while only 6 percent used first-line indents to begin a new paragraph. This represents a sharp contrast with advertising from the 1920s in the United States (Heimann 2004), where first line indents were common.
Evidence on the effects of blank-line spacing between paragraphs
In a lab experiment, approximately 500 Grade 6 and 7 schoolchildren were assigned to read either material with blank-line spacing between paragraphs (and no indent), or material with a first-line indent (and no line-space). In a task that involved retrieving information, the group with the blank-line spacing did about 6 percent better than those with first-line indents (Hartley, Burnhill, and Davis 1978).
Our quasi-experimental analysis suggests that first-line indents are better