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Flashed Face Distortion Effect: Grotesque Faces from Relative Spaces

DOI:10.1068/p6968
Authors:
Jason Tangen at The University of Queensland
Jason Tangen
Sean Christopher Murphy at Voconiq
Sean Christopher Murphy
  • Voconiq
Matthew Thompson at Murdoch University
Matthew Thompson
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Abstract

We describe a novel face distortion effect resulting from the fast-paced presentation of eye-aligned faces. When cycling through the faces on a computer screen, each face seems to become a caricature of itself and some faces appear highly deformed, even grotesque. The degree of distortion is greatest for faces that deviate from the others in the set on a particular dimension (eg if a person has a large forehead, it looks particularly large). This new method of image presentation, based on alignment and speed, could provide a useful tool for investigating contrastive distortion effects and face adaptation.
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We discovered an interesting face distortion effect while preparing a set of face images
for an identification experiment. We obtained a set of faces from a Slovakian data-
base (SmartNet IBC, no date) and eye-aligned them using PsychoMorph (Tiddeman
et al 2001). To check the consistency of the eye alignment, we started skimming through
the images on the computer at a fast pace. After a while, we made a few remarks to one
another about the `aesthetically challenged' faces in the set. They began to appear highly
deformed and grotesque. But after inspecting the especially ugly faces individually, each
of them appeared normal or even attractive.
It seemed that, after continuously flipping through the eye-aligned faces at a steady
rate, each one began to appear as a caricature of itself. If a person had a large jaw,
it looked particularly large, almost ogre-like. If a person had a slender nose, then it
looked remarkably thin. Many of the distortions, however, were quite difficult to artic-
ulate. If we stopped the sequence and returned to these particular faces, however, they
quickly returned to normal. We entertained the idea that Slavic faces were inherently
bizarre, but we replicated the effect with faces from several other databases.
We standardised the presentation rate and found that roughly 4 ^ 5 faces per second
wasideal(seeMovie1intheSupplementaryOnlineMaterialathttp://dx.doi.org/10.1068/
p6968).Aftergazingatacontinuoussequenceforaminuteorso,manyofthefaceswill
appear highly distorted, even monstrous. The degree of distortion is greatest for faces
that deviate from the others in the set on a particular dimension. If one face has an
especially large or pronounced forehead compared to the others in the set, for example,
then it appears particularly bulbous.
Relative encoding seems to drive the effect. That is, forcing the observer to encode
each face in light of the others. By eye-aligning the faces, it becomes much easier to
compare their shape and the relative location of their features, so the differences between
them become more evident. The fast, steady presentation rate may also encourage this
relative encoding. If the faces are not eye-aligned or if they are presented too slowly or
quickly, then the effect lessens. Or, if we insert a brief gap in the sequence, the effect
almost completely disappears (see Movie 2).
This effect is most certainly related to work on adaptation, and the `face distortion
after effect' specifically (Webster and MacLin 1999). In the basic paradigm, participants
study a single artificially distorted face for a few seconds to several minutes followed
SHORT AND SWEET
Flashed face distortion effect: Grotesque faces
from relative spaces
Perception, 2011, volume 40, pages 628 ^ 63 0
Jason M Tangen, Sean C Murphy, Matthew B Thompson
School of Psychology, University of Queensland, St Lucia, QLD 4072, Australia;
e-mail: jtangen@psy.uq.edu.au
Received 24 March 2011, in revised form 26 May 2011; published online 6 July 2011
Abstract. We describe a novel face distortion effect resulting from the fast-paced presentation of
eye-aligned faces. When cycling through the faces on a computer screen, each face seems to become
a caricature of itself and some faces appear highly deformed, even grotesque. The degree of dis-
tortion is greatest for faces that deviate from the others in the set on a particular dimension (eg if a
person has a large forehead, it looks particularly large). This new method of image presentation,
based on alignment and speed, could provide a useful tool for investigating contrastive distortion
effects and face adaptation.
doi:10.1068/p6968
by an unaltered face that now appears distorted in the opposite direction to the adapting
face. Adaptation to a distorted face that is fat, happy, contracted, male, etc, causes
neutral faces to appear thin, sad, expanded, female, etc (see Hills et al 2010 for review).
Similar effects have been demonstrated for distortion effects of identity, ethnicity,
orientation, and attractiveness (Leopold et al 2001; Rhodes et al 2003, 2004; Webster
et al 2004).
There must, however, be some degree of homogeneity among the faces for the
outliers to stand out and for the effect to occur. The distortion effect, therefore, seems
to depend on the outlying dimensions among the images in the set, and these dimen-
sions do not seem to be limited to facial features or configurations. For example,
if a photograph is brightly lit compared to the others, then it appears overexposed.
Presumably, then, the effect relies on the same contrastive mechanism that gives rise
to shape-contrast effects. Suzuki and Cavanagh (1998), for example, demonstrated that
a briefly flashed line distorts a circle into an ellipse that appears elongated orthogo-
nally to the line orientation. Owing to the multidimensional nature of the faces in our
flashed face distortion effect, the resulting distortion is not on any single dimension,
but on every dimension along which the face images vary. In contrast, face distortion
after effects commonly result from prolonged exposure to one face with a single exagger-
ated dimension defined by the experimenter, such as the distance between the eyes.
The dimensions that can be caricatured in our effect, therefore, are not limited to those
that can be easily defined and modified by experimenters. For example, only Greeble
experts (Gauthier and Tarr 1997) could determine whether a Greeble's `belly horn' is
abnormally large or pointy (see Movie 3). Indeed, it becomes difficult to identify or label
the basis of the face distortions if the faces are rotated 1808(see Movie 4), much like the
Thatcher effect (Thompson 1980).
Traditionally, face adaptation effects have been interpreted within the framework
of Valentine's (1991) face-space model, in which faces are encoded by their positions in
a multidimensional space. A variety of similar metaphors have been used in conjunc-
tion with this model, such as a two-pool neural net and exemplar or prototype accounts
(Robbins et al 2007). While it is too early to know which model or theoretical framework
will be the most useful in defining this flashed face distortion effect, and predicting its
boundary conditions, face-space accounts or shape-contrast effects may serve as useful
starting points for investigating this interesting effect.
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ß 2 011 a Pion publication
630 J M Tangen, S C Murphy, M B Thompson
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Orientation-Contingent Face Aftereffects and Implications for Face-Coding Mechanisms
Article
Humans have an impressive ability to discriminate between faces despite their similarity as visual patterns. This expertise relies on configural coding of spatial relations between face features and/or holistic coding of overall facial structure. These expert face-coding mechanisms appear to be engaged most effectively by upright faces, with inverted faces engaging primarily feature-coding mechanisms. We show that opposite figural aftereffects can be induced simultaneously for upright and inverted faces, demonstrating that distinct neural populations code upright and inverted faces. This result also suggests that expert (upright) face-coding mechanisms can be selectively adapted. These aftereffects occur for judgments of face normality and face gender and are robust to changes in face size, ruling out adaptation of low-level, retinotopically organized coding mechanisms. Our results suggest a resolution of a paradox in the face recognition literature. Neuroimaging studies have found surprisingly little orientation selectivity in the fusiform face area (FFA) despite evidence that this region plays a role in expert face coding and that expert face-coding mechanisms are selectively engaged by upright faces. Our results, demonstrating orientation-contingent adaptation of face-coding mechanisms, suggest that the FFA's apparent lack of orientation selectivity may be an artifact of averaging across distinct populations within the FFA that respond to upright and inverted faces.
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