EURON and THEME joint PhD meeting

91
EURON and THEME joint meeting 2011
The influence of spatial distortion during body
perception: an event- related potential study
*M. E. Siwek 1,2 , B. Suchan 2 , D. Soria-Bauser 2 , I. Daum 2 .
1 Cell. and Systemic Neurophysiol., Federal Inst. For Drugs and Med. Devices (BfArM), Bonn, Germany;
2 Dept. of Neuropsychology, Inst. of Cognitive Neurosci., Bochum, Germany.
Like human faces, human bodies are indispensable for communication as well
as for perceiving another’s emotion correctly while providing information about
gender, age and intentions of other individuals becoming familiar with recurred
exposure over one’s lifetime. Concerning the high importance both stimuli classes
for our daily routine, the question arises, what kind of mechanisms are needed
in the human brain to ensure specialized visual and perceptual processing of
both, facial and bodily expressions. The current study was aimed to investigate
behavioral and electrophysiological influences of inversion (rotation around 180°)
as well as changes of body perception depending upon the degree of spatially
distorted stimuli referring to a possible disruption of configural processing
mechanism. Thereby, configural processing continuum distinguishes different
processing levels of human body shapes according to their spatial relations
among internal features.
In this case smoothed body images as one possible stimulus manipulation were
used in the current study. Spatial distortion or smoothing was done by Gaussian
filtering (low-pass filtering) of the original pictures with filter widths of 1, 3, 5
and 7 mm. Thereby, the reduction in high-frequency noise by using low- pass
filters is obtained at the cost of a loss of spatial resolution. Concerning this the
presentation of less information/ details containing within a stimuli caused by
different smoothing degrees might influence the encoding of basic features that
are necessary for the processing of body parts and individual representation
of the body as a whole. On the electrophysiological level body specific eventrelated
components, N170 and P100 were investigated. For both, N170 and P100
amplitudes, the inversion effect was replicated. On the behavioral level increasing
smoothing steps lead to higher error rates and efficiency scores. In case of
electrophysiological measures an effect of spatial distortion was obtained for the
P100 latency but not for the N170 component. Overall, the findings support that
the N170 being elicited by bodies is a robust phenomena concerning spatially
manipulated depictions of human bodies.