Studies in Perception and Action V M. A. Grealy &
J. A. Thomson (Eds.)
© 1999 Lawrence Erlbaum Associates, Inc.
Are Haptic Perceptions Independent? Megan M. CooperCESPA, University of Connecticut, Storrs, USAPrevious investigations of dynamic touch have suggested that, in
wielding an occluded rod, the nonvisible perceptions of whole rod length
and center of percussion are different functions of the inertial properties
of that object (
Turvey, in press). Rod length
has been shown to depend on the inertia tensor, Iij, and in particular on
the maximum eigenvalue (I1). Center of percussion (CP) depends on the
ratio of I1 to static moment. The implication that the perceptions are
independent covariants of these inertial properties was tested using the 3-
step procedure of Ashby and
Townsend ( 1986). The logic of the analysis
rests on the definition of certain key terms:
|• ||Perceptual independence exists if the perception of one dimension of a
given stimulus, A (e.g. I1), in no way interacts with or is contingent upon
the perception of another, B (e.g. CP).|
|• ||Decisional separability exists if the decision to report a particular
perception of dimension A does not depend on the level of B.|
|• ||Perceptual separability exists provided the perceptual effects of
dimension A do not depend on the level of B.|
A logical test for perceptual independence cannot proceed
without first satisfying that conditions of separability hold. Step 1 is a
global test of separability, the test of partial contingent uncertainties (see Garner &
Morton, 1969). If these values do not differ significantly from
zero, then separability holds. Step 2 is a local test of separability, the test
of marginal response invariance (see Ashby &
Townsend, 1986). If the
perceived values of A do not vary with the level of B, then the local test of
separability passes. Step 3 is the test for perceptual independence, termed
sampling independence (see Ashby &
Townsend, 1986). If the joint
probability of making a particular response (P(ai, bj)) equals the product
Questia, a part of Gale, Cengage Learning. www.questia.com
Book title: Studies in Perception and Action V:Tenth International Conference on Perception and Action: Aug. 8-13, 1999, Edinburgh, Scotland.
Contributors: Madeleine A. Grealy - Editor, James A. Thomson - Editor, International Conference on Perception and Action - OrganizationName.
Publisher: Lawrence Erlbaum Associates.
Place of publication: Mahwah, NJ.
Publication year: 1999.
Page number: 81.
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