Tourangeau, Roger, Mick P. Couper, and Frederick G. Conrad. 2004. "Spacing, Position, and Order - Interpretive Heuristics for Visual Features of Survey Questions." Public Opinion Quarterly, 68(3): 368-393.
We present the results of six experiments that demonstrate the impact of visual features of survey questions on the responses they elicit, the response process they initiate, or both. All six experiments were embedded in Web surveys. Experiments I and 2 investigate the effects of the placement of nonsubstantive response options (for example, "No opinion" and "Don't know" answer options) in relation to the substantive options. The results suggest that when these options are not differentiated visually (by a line or a space) from the substantive options, respondents may be misled about the midpoint of the scale; respondents seemed to use the visual rather than the conceptual midpoint of the scale as a reference point for responding. Experiment 3, which varied the spacing of the substantive options, showed a similar result. Responses were pushed in the direction of the visual midpoint when it fell to one side of the conceptual midpoint of the response scale. Experiment 4 examined the effects of varying whether the response options, which were arrayed vertically, followed a logical progression from top to bottom. Respondents answered more quickly when the options followed a logical order. Experiment 5 examined the effects of the placement of an unfamiliar item among a series of similar items. For example, one set of items asked respondents to say whether several makes and models of cars were expensive or not. The answers for the unfamiliar items depended on the items that were nearby on the list. Our last experiment varied whether a battery of related items was administered on a single screen, across two screen!, or with each item on its own screen. The intercorrelations among the items were highest when they were all on the same screen. Respondents seem to apply interpretive heuristics in assigning meaning to visual cues in questionnaires. They see the visual midpoint of a scale as representing the typical or middle response; they expect options to be arrayed in a progression beginning with the leftmost or topmost item; and they expect items that are physically close to be relata to each other conceptually.