Abstracts 2005 - The Psychonomic Society

Posters 3001–3007 Friday Evening
POSTER SESSION III
Sheraton Hall, Friday Evening, 5:30–7:00
• TOUCH •
(3001)
Training Reduces the Crossed-Hands Deficit in Temporal Order
Judgments. JAMES C. CRAIG & ADRIENNE N. BELSER, Indiana
University—It has been shown that crossing the hands results in tactile
temporal order thresholds that may be more than three times larger
than those with uncrossed hands, a crossed-hands deficit (CHD).
These results suggest that with crossed hands, subjects have difficulty
remapping the tactile inputs to correspond with the spatial positions
of the hands. The effect of training on the CHD was examined. At the
beginning of training, the crossed threshold was 458 msec and the uncrossed
threshold was 65 msec, a CHD of 393 msec. At the end of training,
the comparable values were 111 and 50 msec, a CHD of 61 msec.
In another experiment, the CHD initially was 79 msec, dropping to
only 16 msec in the last session. Training did not eliminate but did
greatly reduce the CHD. The implication is that significant remapping
occurs with modest amounts of training.
(3002)
The Effects of Force and Conformance on Tactile Sensitivity. GREG-
ORY O. GIBSON & JAMES C. CRAIG, Indiana University (sponsored
by Gabriel P. Frommer)—The effects of force and conformance
on intensive and spatial processing were examined with several measures
of tactile sensitivity. Measures were made at two locations (fingerpad,
fingerbase) that differ in sensitivity and density of innervation.
Psychometric functions were generated for two measures of
spatial sensitivity and one measure of intensive sensitivity at two
forces (50 and 200 g). Results indicated that increasing force led to
improvement on the intensive task, but not on the spatial tasks. Skin
conformance measurements were made at both test sites. Conformance
was found to be a joint function of force and groove width. Furthermore,
performance on the intensive task could be predicted by
conformance. The results are consistent with the view that increasing
conformance increases neural activity in the afferent fibers; this increase
improves performance on intensive tasks but has little effect on
the quality of the spatial image.
(3003)
Haptic Concepts in the Blind. DONALD HOMA, KANAV KAHOL,
PRIYAMVADA TRIPATHI, LAURA BRATTON, & SETHURAMAN
PANCHANATHAN, Arizona State University—The acquisition of haptic
concepts by the blind was investigated. Each subject—either blind or
normally sighted—initially classified eight objects into two categories,
using a study/test format, followed by a recognition/classification test
involving old, new, and prototype forms. Each object varied along three
relevant dimensions—shape, size, and texture—with each dimension
having five values. The categories were linearly separable in three dimensions,
and no single dimension permitted 100% accurate classification.
The results revealed that blind subjects learned the categories
slightly more quickly than their sighted controls and performed at
least as well on the later memory tests. On the classification test, both
groups performed equivalently, with the category prototype classified
more accurately than the old or new stimuli. On the recognition test,
all subjects, including the blind, false alarmed to the category prototype
more than to any new pattern. These results are discussed in
terms of current views of categorization.
• MULTISENSORY INTEGRATION •
(3004)
Kinesthetic Egocenter Is Used in Visually Directed Manual Pointing.
KOICHI SHIMONO, Tokyo University of Marine Science and Technology,
& ATSUKI HIGASHIYAMA, Ritsumeikan University—We examined
the hypothesis (Howard, 1982; Shimono & Higashiyama, 2005)
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that if we point a target manually without viewing our hands, its direction
is judged from the kinesthetic egocenter, but not from the visual
egocenter. For each of 8 observers, we estimated locations of the
visual and the kinesthetic egocenters by using the Howard and Templeton
method and required them to point to a near or far target without
viewing their hands. The angle, which was formed by the sagittal
plane going through the egocenter (visual or kinesthetic), with the line
joining the egocenter and the pointed position, was determined for
each target. The angles for the near targets were better described as a
function of the angle for the far targets when they were represented
using the kinesthetic, rather than the visual, egocenter.
(3005)
Contrast Effects Between Concurrently Perceiving and Producing
Movement Directions. JAN ZWICKEL, MARC GROSJEAN, &
WOLFGANG PRINZ, Max Planck Institute for Human Cognitive and
Brain Sciences—Schubö, Aschersleben, and Prinz (2001) proposed a
model to account for the contrast effects (CEs) that arise during the
concurrent perception and production of feature-overlapping events. For
example, the model can explain why producing a medium-amplitude
movement while simultaneously watching a large-amplitude motion
leads to a reduction in size of the produced movement (i.e., a CE in
action) and to an increase in size of the perceived motion (i.e., a CE in
perception). Using movement direction as the overlapping perception–
action dimension, the present experiments sought to evaluate two
untested predictions of the model: (1) The size of the CEs in perception
and action should be monotonically related and (2) the size of the CEs
should depend on the angular proximity between perceived and produced
movements. In agreement with the model, CEs were found in
both perception and action; however, neither of these specific predictions
were confirmed.
(3006)
Cross-Modal Interactions in the Perception of Auditory Spatial Sequences.
SHARON E. GUTTMAN, LEE A. GILROY, & RANDOLPH
BLAKE, Vanderbilt University—To create meaningful descriptions of
reality, the perceptual system must combine inputs from multiple sensory
modalities. Previously, we have shown that one consequence of
multimodal integration is cross-modal encoding: Temporal information
presented through visual input automatically becomes represented
using an auditory code. Here, we investigate the converse and
ask whether spatial information presented through auditory input is
automatically represented using a visual code. Participants made
same/different judgments regarding two auditory sequences consisting
of white noise bursts presented serially at four distinct spatial locations.
Auditory/visual interactions suggested cross-modal encoding:
Incongruent visual–spatial information diminished task performance
relative to a baseline condition, whereas congruent visual–spatial information
improved performance. Further experimentation suggested that
this cross-modal interference is partially attributable to visual capture
of the auditory spatial information. Together, these results indicate
that the perceptual system employs multiple, situationally dependent
strategies to create unitary representations from multimodal input.
(3007)
Differentiable Effects of Size Change on Repetition Priming in Vision
and Haptics. ALAN C. SCOTT & RANDOLPH D. EASTON, Boston
College—Previous research has demonstrated that object identification
on repeated exposures is performed more quickly than initial
identification—a phenomenon referred to as priming (e.g., Cave &
Squire, 1992). Introducing a size change between study and test has
no effect on the facilitating effects of repeated exposures when items
are presented visually but does reduce facilitation when items are presented
haptically. In recent research, we have demonstrated haptic-tovisual
cross-modal priming with no effects of size change, thereby
suggesting the existence of bimodal object processing. It was believed
that if object processing was entirely bimodal in nature, increasing the
delay between study and test would eliminate the unique effects of