Biomedical Engineering Reference
In-Depth Information
Chapter 4
Affordance Perception and the Visual
Control of Locomotion
Brett R. Fajen
Abstract
When people navigate through complex, dynamic environments, they
select actions and guide locomotion in ways that take into account not only the envi-
ronment but also their body dimensions and locomotor capabilities. For example,
when stepping off a curb, a pedestrian may need to decide whether to go now ahead
of an approaching vehicle or wait until it passes. Similarly, a child playing a game of
tag may need to decide whether to go to the left or right around a stationary obstacle
to intercept another player. In such situations, the possible actions (i.e., affordances)
are partly determined by the person's body dimensions and locomotor capabilities.
From an ecological perspective, the ability to take these factors into account begins
with the perception of affordances. The aim of this chapter is to review recent theo-
retical developments and empirical research on affordance perception and its role in
the visual control of locomotion, including basic locomotor tasks such as avoiding
stationary and moving obstacles, walking to targets, and selecting routes through
complex scenes. The focus will be on studies conducted in virtual environments,
which have created new and exciting opportunities to investigate how people per-
ceive affordances, guide locomotion, and adapt to changes in body dimensions and
locomotor capabilities.
4.1 Introduction
To successfully interact with one's environment (real or virtual), it is necessary to
select actions and guide movements in ways that take one's body dimensions and
movement capabilities into account. To illustrate this point, consider what would
happen if the designer of a virtual environment (VE) were to dramatically alter the
dimensions or dynamics of the user's virtual body. In a VE, one's virtual body could
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Department of Cognitive Science, Rensselaer Polytechnic Institute,
Troy, NY, USA
e-mail: fajenb@rpi.edu
B. R. Fajen
