Biomedical Engineering Reference
In-Depth Information
target
interceptable
not interceptable
Fig. 4.7
Top-down
view of an observer intercepting a moving target. The gradient illustrates how
the speed needed to intercept the target varies with direction of locomotion. The
dashed line
indicates
the direction in which the observer would need to move to intercept the target as quickly as possible.
This line also partitions the space into directions in which the target is interceptable and directions
in which the target is not interceptable due to limits on how fast the observer can move
guided interception remains unknown. Further experiments in VEs are needed to
investigate the information and control strategies used to coordinate steering and
speed during interception.
To summarize, continuously controlled visually guided actions such as intercept-
ing a moving target on foot, require actors to guide their movements in ways that
take their locomotor capabilities into account. This means that affordance percep-
tion may play a role not only in the selection of appropriate actions but also in the
continuous guidance of locomotion. In this section, I described how information that
specifies affordances for action selection (i.e., passability) may also be used to guide
locomotion during interception.
4.9 Conclusions
Virtual environments have already proven to be a powerful tool for studying many
aspects of perception and action [
39
]. In this chapter, I illustrated how VEs have also
been used to study the perception of affordances and their role in the control of loco-
motion. This research has provided insights into the means by which people select
actions and guide movements in ways that take their body dimensions and locomotor
capabilities into account. The findings build upon previous research inspired by the
ecological approach and contribute to a more general, affordance-based approach to
visually guided locomotion.
Given the well-documented differences in perception and motor control in virtual
versus real environments (e.g., [
12
,
16
,
17
,
31
]), it is reasonable to ask whether
