S1 (FriAM 1-65) - The Psychonomic Society

Saturday Morning Papers 165–171
University of Virginia—Traditionally, researchers in perception and
cognition have overlooked the fact that brains exist within bodies. Recent
research, however, suggests that the body helps to define how
people see and understand the outside world. The goal of this symposium
is to provide an integrated overview of state of the art research
on embodied perception and cognition. The speakers represent a diversity
of approaches and techniques directed at the study of how having
a body and moving that body changes the way people perceive,
represent, and understand their physical and social environments. The
central topics in this symposium include perception–action coupling,
spatial perception, attention, motion perception, action understanding,
and representational momentum. The presentations will be designed
for a wide audience, and thus, will be of interest to experts and nonexperts
alike.
10:00–10:15 (165)
The Perception of Action-Scaled Affordances. BRETT FAJEN,
Rensselaer Polytechnic Institute—What kinds of theoretical ideas are
needed to do justice to the inextricable link between perception and
action that is characteristic of so many routine and skilled behaviors?
I will argue that the tight linkage between perception and action is
neatly captured by the theory of affordances, according to which
movements are guided by perceiving possibilities for action. My focus
will be on action-scaled affordances—that is, possibilities for action
that are constrained by limitations on actors’ ability to move, such as
how fast one can run, how sharply one can turn, and how hard one can
decelerate. To perceive action-scaled affordances is to perceive the
world in units that are directly related to one’s action capabilities. I
will show how the perception of action-scaled affordances plays a fundamental
role in performing tasks such as steering, braking, and intercepting,
for which information in optic flow and movement are
tightly coupled.
10:20–10:35 (166)
How Motor Constraints and Experience Influence Perception.
GÜNTHER KNOBLICH, Rutgers University, Newark—Do our action
capabilities influence how we perceive our own actions and those of
others? Cognitive psychologists and neuroscientists have long assumed
that perception and action are clearly separated. Contrary to this supposition,
I will defend the view that perception and action are closely
linked. I will present two recent studies supporting this view. The first
study demonstrates that Fitts’s law does not only constrain how we
move ourselves but that it also constrains what we perceive as doable
for others. The second study addressed the role of expertise in perception.
It demonstrates that keyboard actions affect pitch perception
in pianists but not in novices. Such results strongly support the assumption
that the motor system plays a crucial role in perception.
10:40–10:55 (167)
The Bio-Energetic Scaling of Perceived Space. DENNIS PROF-
FITT, University of Virginia—The visual perception of spatial layout
relates people’s body and goals to the opportunities and bio-energetic
costs of acting in the environment. Spatial perceptions are influenced,
not only by optical and ocular-motor information, but also by people’s
purposes and physiological state. For example, under constant viewing
conditions, the apparent incline of hills increases when people are
tired or encumbered by wearing a heavy backpack. Hills also appear
steeper to people who are experiencing blood glucose depletion, are
in poor physical condition, or are elderly and in declining health, compared
with those who are young, healthy, and fit. Apparent distances
are similarly influenced by the bio-energetic state of the body; reduced
bio-energetic potential results in an increase in apparent distances.
In essence, the perceptual system scales spatial layout to the
bio-energetic costs of intended actions.
11:00–11:15 (168)
Influences of the Body on Spatial Attention. CATHERINE L. REED
& JOHN P. GARZA, University of Denver—The study of spatial at-
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tention traditionally focuses on how it is influenced by the location of
objects within the visual environment. However, a primary function
of spatial attention is to plan physical actions. When events occur in
the world, we need to integrate visual information with our current
body position to help us prepare effective responses to these events.
Furthermore, our current actions can subsequently influence further
deployments of attention. Thus, spatial attention must be considered
within the context of the body. In this talk, we will present research
demonstrating that one’s own body can influence spatial attention
mechanisms: Hand position, function, and action are shown to be important
influences on the prioritization of functional space near the
body and the direction of attention. Together this work emphasizes a
need for an embodied theory of spatial attention.
11:20–11:35 (169)
Seeing Yourself in Others. MAGGIE SHIFFRAR, Rutgers University,
Newark—Effective social behavior requires the accurate and rapid
perception of other people’s actions. When a nearby person moves toward
you, your visual system analyzes that movement so that you can
determine whether that person is reaching out to shake your hand, to
fix your tie, or to punch you. Psychophysical studies of the perception
of human movement indicate that observers use their own bodily
experience to interpret the actions of other people. For example, observers
demonstrate greater visual sensitivity to point-light depictions
of their own actions than to the actions of other people. This sensitivity
enhancement is independent of visual experience. Indeed, enhanced
visual sensitivity to self-generated motion occurs even when
the observer’s past actions appear on someone else’s body. Finally, a
study of hand perception by individuals born without hands further
supports the hypothesis that observers use internal representations of
their own body to perceive movement.
11:40–11:55 (170)
Predicting Movements That Are Hard to Perform: Biomechanics
and Representational Momentum. MARGARET WILSON &
JESSY LANCASTER, University of California, Santa Cruz—Human
bodies are perceived differently than other stimuli—specifically, biomechanical
knowledge of one’s own body is recruited in perceiving
others’ bodies (e.g., Kourtzi & Shiffrar, 1999). Wilson and Knoblich
(2005) propose more specifically that motor knowledge is used for
perceptual prediction, to cast forward into the immediate future and
simulate probable outcomes of others’ movements. We support this
claim using the phenomenon of representational momentum (RM), by
showing that observers are sensitive to biomechanical constraints in
generating these simulations. RM of human bodies is maximized for
downward movements, and movements shown in the direction that
they were originally filmed. In contrast, upward and backward movements
exert a “drag” on the forward projection of RM. All the shown
movements are biomechanically possible, but some are more natural
and easy than others. This appears to affect observers’ ability to generate
robust simulations of these movements.
12:00–12:15 (171)
Tool Use and Intention Affect Perceived Distance. JESSICA WITT,
Purdue University—Near space is defined relative to the extent of
arm’s reach, and thus, near space is scaled by reachability distance.
Tool use extends reaching extent, and in so doing, it rescales spatial
perceptions within near space. Compared to when no tool is held, objects
that are beyond arm’s reach appear closer when people intend to
reach with a tool that allows the objects to be touched. This is one of
several examples demonstrating that behavioral potential affects perception.
Little is known, however, about what underlying mechanisms
might be responsible for such action-specific influences on perception.
Experiments are presented that implicate motor simulation as a
mediator of these effects. When people view a surface with an intention
to act, people perform a motor simulation of the intended action,
and thereby, scale perceived space in terms of the simulated action and
its outcome.