Theoretical Foundations of Information Visualization - Information Visualization: Human-Centered Issues and Perspectives - page 59

Fig. 1. Topics in a Formalized Information Visualization Course. Dark grey topics are based
upon formal foundations in other disciplines; light grey topics are yet-to-be-developed visuali-
zation-specific formal foundations.

4.2 A Move to Visualization Formalisms: The Two Models

There have been several recent calls for an establishment of a “theory” and “science”
behind visualization [24,25]; this need can be partially addressed via formal scientific
models. If we accept that information visualization needs a formal foundation, the
question remains whether the existing models from perceptual psychology and cogni-
tive science are sufficient. The problem with these formalisms is they do not address
the specific problems of visualization. While they provide general guidelines, models
from non-visualization fields do not consider the context of the visualization envi-
ronment - the user and the computer. What is needed is a set of formal foundations
that bridges the gap between the general human experience and the visualization do-
main (Figure 1). We propose two models for this purpose: an exploration model that
incorporates the user's interaction with the visualization and the dynamic aspects of
their analysis, and a transform design model which encapsulates the depiction and
constructive aspects of the visualization. These models would abstract fundamental
principles of visualization science and design, and thus proscribe (via their predictive
power) empirically driven practices.

4.3 Visualization Exploration Model

Visualization exploration is a goal-driven task incorporating visual search and infor-
mation seeking. It is an iterative process - a user creates a visualization result, evalu-
ates its worth, and then manipulates the visual parameters (e.g. color maps, selection
regions) creating new results until satisfied. Thus, any formal model of computer-
mediated visual exploration must capture the cognitive operations and how those
realized actions manipulate the visualization. Cognitive operations are the domain of
cognitive science, and several methods exist to model the human analysis process
[26]. To bridge this work to visualization, two additional levels are needed: first, a
description of the visual information search process and how it affects human cogni-
tion; second, a model of how the visualization session evolves due to human interac-
tion. Visual sensemaking models such as the information foraging work of Pirolli and
Card [27] begin to address the first need. Formalisms that capture the range of human-
visualization interactions are targeted at the second [28,29,30].