Minimizing Cognitive Load in Map-Based Navigation: The Role of Landmarks

Introduction

Reading maps can be tricky; in particular when this happens during driving. We would like to minimize any unnecessary effort that navigators experience in using maps to locate themselves in their environment or figure out a route to their destination. This motivates efforts to find the optimal way in which the information on display is represented. People's spontaneous sketches of environment they have experienced primarily through navigation are oriented as if they imagined themselves entering the environment from the bottom of the page (for example, Tversky, 1981). Navigators typically prefer maps that are oriented “heads up” that is, when the “up” direction in the map, the top of the page, corresponds to the direction the person is facing (for example, Levine, 1982). A map oriented this way is called aligned and preference for such maps is called the alignment effect.

Modern technology offers ways to present maps that are always aligned. This is typically done in on-board navigation systems based on Global Positioning. Such systems provide the current position indicated on the map; with the destination of the individual user known, the orientation of the display can therefore easily be adjusted to align the map. Maps that are placed on public display, however, will have to indicate possible destinations in several directions, making it impossible to present them in an aligned fashion. This raises a question, whether there are other ways to facilitate map usage and, if so, what is their relation with the alignment effect? Specifically, is there a natural way to annotate maps to decrease the cognitive effort required to mentally navigate, in particular, in misaligned conditions?

For meaningless shapes, salient “landmarks” are known to facilitate mental rotation (Hochberg and Gellman, 1977). Landmarks are a natural element in spontaneous sketch [Page 25]maps and in mental representations of environments (for example, Denis, 1997; Taylor and Tversky, 1992a, 1992b; Tversky and Lee, 1998, 1999). Properly placed and designed, landmarks might provide cues for making mental navigation decisions that facilitate map use.

The study of whether and when landmarks facilitate map reading has, besides practical, also more fundamental implications, as it allows us to investigate what type of mental processes are being used in navigation. Facilities to assist navigation may address either of two types of information processing. The first is referred to alternatively as mental rotation or reorientation (for example, Shepard and Metzler, 1971; Corballis and Nagourney, 1978; Eley, 1982, 1988; Evans and Pezdek, 1980; Aretz and Wickens, 1992) because it can be done in at least two ways: either by mentally rotating the map, or by reorienting one's own direction within the map. These two possibilities correspond, respectively, to two major ways of experiencing an environment; from a survey or overview perspective or from a route or embedded perspective (for example, Taylor and Tversky, 1992; Tversky, 1996; Zacks, et al., 2002). The present project does not attempt to distinguish the conditions inducing people to adopt each transformation, though other research has made efforts to do so (for example, Bryant and Tversky, 1999; Zacks, et al., 2002). We will, however, be able to determine whether an overview or embedded perspective is chosen in our experiments.

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