112 Understanding Rational Decision Making
rate, but they were able to recognize 93% at a two-second exposure rate.^67 Recognition of more
complex pictures requires even longer exposure rates.^68 Such longer exposure rates increase image
recognition and recall independently of the viewer’s opportunity to verbally label the picture.^69
After a one-year delay, just two exposures enabled the viewers in one study to recognize 72% of
the images they viewed.^70 However, more than two exposures do not add signifi cantly to viewers’
recognition rates.^71
Audiences perceive graphs in much the same way they perceive pictures—by fi xating manytimes on the graph’s different regions and elements. In an eye-tracking study of viewers inter-
preting line graphs, viewers perceived the graphs by making numerous fi xations on different
regions of them.^72 In addition to fi xating on the trend lines, viewers frequently fi xated on the
variable names, variable values, and the X and Y axes. In other words, audiences viewing a chart
or graph repeatedly fi xate on those elements that are most relevant to evaluating its content.
The viewers in the study also spent a large portion of their time fi xating on the graphs’ captions
and legends as well as on the values of the variables. Not surprisingly, the viewers made more
fi xations when viewing complex graphs as opposed to simple ones.
In a follow-up eye-tracking study, for relatively simple graphs, such as the line graph in Fig-ure 3.8 , viewers averaged 29 fi xations and spent an average of 33 seconds viewing each graph. For
the more complex graphs in the study, viewers averaged 40.5 fi xations and spent an average of 40.6
seconds viewing each graph.^73
FIGURE 3.8 A Viewer’s Eye-Fixation Pattern Interpreting a Line Chart
Source: Carpenter and Shah (1998, p. 86)