=Paper=
{{Paper
|id=Vol-1419/paper0015
|storemode=property
|title=Exploring Body Holistic Processing Investigated with Composite Illusion
|pdfUrl=https://ceur-ws.org/Vol-1419/paper0015.pdf
|volume=Vol-1419
|dblpUrl=https://dblp.org/rec/conf/eapcogsci/SzatmariL15
}}
==Exploring Body Holistic Processing Investigated with Composite Illusion==
https://ceur-ws.org/Vol-1419/paper0015.pdf
Exploring body holistic processing investigated with composite illusion
Dora E. Szatmári (szatmari.dora@pte.hu)
University of Pécs, Institute of Psychology Ifjúság Street 6.
Pécs, 7624 Hungary
Beatrix Lábadi (labadi.beatrixt@pte.hu)
University of Pécs, Institute of Psychology Ifjúság Street 6.
Pécs, 7624 Hungary
Abstract
information, which refers to the spatial position of the
The aim of the present study was to explore the holistic
processing of the human body shape. Composite illusion is individual features of parts. The first-order relational
used as a marker to demonstrate face holistic processing. information means the relative positions of the individual
Previous studies showed that adults find it difficult to name elements, such as the nose is above the mouth. Using this
the top half of a familiar face when it has been aligned with information, we are able to identify a stimulus as a face, a
the bottom half of a different face compared with misaligned house, or a car. Second-order relational information refers to
condition. The current study aimed to explore body shape the spatial and metric relations between the internal
processing using composite effect. In our study body stimuli
were generated by a computer program. Body shapes varied
elements (e.g. distance between the eyes). Based on this
by BMI having a thinner and a fatter version as well. Face information we can recognize the individual exemplars. The
composite illusion was also investigated as a control. first-order relational information helps us to recognize that
Composite illusion was observed for faces as reaction time we perceive a face, whereas the second-order relational
was significantly faster and performance was better for information helps us to identify whose face we perceive
misaligned faces compared to aligned faces. For human body (Reed et al., 2006).
shapes composite illusion was observed nevertheless merely The conception of first- and second-order relational
inverted bodies. Participants performed superiorly for
inverted misaligned bodies compared with inverted aligned information comes from Maurer, Le Grand and Mondloch
bodies. (2002). Contrary to the continuum theory, their hypothesis
consists of three types of processing; the first-and second-
Keywords: composite illusion; holistic processing; body order relational information, and the third one is the holistic
perception; face perception; configural processing
processing, which derives from the first-order relational
information. When the first-order relations are detected, it is
Face and body shape processing harder to collect individual features, thus we tend to process
Compared to face perception processing, body shape the stimulus as a Gestalt. We perceive faces as a unique
perception is a less studied area, although perception of face Gestalt instead of the combination of single features.
and body share many processes. Both have abstract The specific marker of the holistic processing is the
configural properties, as bodies and faces consist of parts composite face effect which was demonstrated by Young,
(eye, mouth, arm, leg, etc.), which characterize all faces and Hellawell and Hay (1987). This perceptual illusion was
bodies. The configural processing involves spatial positions originally described as naming the top half of a familiar face
of individual parts, which are permanent to distinguish is more difficult when it is aligned with the bottom part of
individual bodies and faces (Slaughter, Stone and Reed, another face than when the two face parts are misaligned
2004). On the other hand, people perceive both stimuli (the face cut halved horizontally under the eyes).
together and quite frequently, so they become experts in Performance on the same trials is poorer in the aligned
face and body processing. In the literature configural and condition than in the misaligned condition, with longer
holistic processing are usually considered as synonymous response times and worse accuracy. In upright aligned
terms, whereas these two processing types can be well condition the face is processed holistically, thus the
distinguished. However, there is no consensus about the identification of the top half becomes problematic compared
definition of holistic and configural processing, and how we with misaligned condition. When faces are inverted, the
can distinguish them based on their functions. The composite effect either disappears or is decreased. The
configural processing continuum is from feature-based to composite face illusion can be observed even with faces that
holistic processing. According to the feature-based are not biologically possible and whose first-order relations
processing, objects are recognized via local feature were disrupted (de Heering, Wallis and Maurer, 2012;
information, such as houses. Objects recognized holistically Rossion and Boremanse, 2008).
as undifferentiated wholes such as faces, are on the other
end of the continuum called holistic processing (Reed et al., Inversion effect
2006). The configural processing can be divided into two
Inversion effect was first studied for faces, but then it was
mechanisms using first- and second-order relational
extended to bodies. The inverted picture of a body or a face
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impaired the recognition with increasing the reaction time posture configuration is processed in a holistic way. In the
compared to the upright presented stimuli (Tanaka and present study we intended to use the same experiment
Farah, 1993; Reed et al., 2003; Reed et al., 2006). These design as Soria Bauser, Suchan and Daum (2011). Our aim
findings have been supported by brain imaging studies was to explore body shape processing using composite
(Reed et al., 2003). Additionally, the effect was supported effect. Previous identity-based studies (Soria Bauser,
for several body postures, but only for biomechanically Suchan and Daum, 2011; Robbins and Coltheart, 2012)
possible poses. Some studies found that the body inversion where the stimuli were pictures of humans wore more or
effect appears merely for the whole body, whereas no less the same clothes. Their hairstyle differentiated (Soria
inversion effect occurs for isolated body parts and for Bauser, Suchan and Daum, 2011), thus it could affect the
horizontally cut half bodies (Reed et al, 2006). Findings results, because participant had to tell whether the top half
suggest better performance for body part recognition in the of the first and second pictures were identical or different.
context of the whole body than when they are in isolation. However in the study of Robbins and Coltheart (2012), the
five individuals were clothed in the same garments with a
Body holistic processing swimming cap. Additionally, there were other effects which
A previous study (Soria Bauser, Suchan and Daum, 2011) could have affected the results, like wearing clothes or the
intended to explore whether body shape is processed lengths of the t-shirts. In summary, it can be stated that it
holistically, like faces or feature-based processing. The was not only the shape of the body that affected the
human body and face have similarities (Reed et al., 2006), processing of the body shapes, but also the appearance. The
but it is still unclear which type of processing is involved in aim of our experiment was to create stimuli which are
body shape perception. Face holistic processing is studied controlled and where merely the shape of the body affects
by inversion effect (Tanaka and Farah, 1993; Reed et al., the participants’ responses. Our experiment is a revised
2003; Reed et al., 2006) and composite illusion (Hellawell identity-based study, where the related stimulus bodies have
and Hay, 1987; de Heering, Wallis and Maurer, 2012; the same identity, but different body shape. The computer-
Rossion and Boremanse, 2008). Inversion effect was also generated model makes it possible to create the same
tested for body shapes (Reed et al., 2003; Reed et al., 2006), identity with a different body shape. We used only the
but composite illusion has been so far used once to classic horizontal composite effect because, previous
investigate body holistic processing (Soria Bauser, Suchan identity-based body composite effect studies (Soria Bauser,
and Daum, 2011). In this study black and white photographs Suchan and Daum, 2011; Robbins and Coltheart, 2012),
of 15 women and 15 men were used, with the faces masked have mixed results. Our aim was to clarify whether body is
and same clothes being worn in each picture. However, the processed holistically like faces. Furthermore, we used body
T-shirts were the same in all photographs and the jeans were stimuli with heads, because body processing uses first-order
different with all with all the models. All the stimuli were configural information, so it is clear, that heads are above
halved horizontally and were presented aligned, or shoulders, thus bodies without heads would be an unnatural
misaligned, upright, or inverted. The same procedure was stimulus.
used for faces. The pictures were presented in same-
different task. Reaction times, accuracy and efficiency Method
scores were examined. The study revealed composite
illusion in face, because the participants were faster, more Participants Altogether 41 persons participated in the
accurate, and more efficient in misaligned faces compared experiment, 10 men and 32 women, all of them were right
to aligned faces, but no composite illusion was found in handed. Mean age was 23.7 years SD=5.1, the age range
bodies. This means face process is holistic; we could not varied from 20 to 49 years old. Four subjects were excluded
perceive it as separate parts, but according to these findings, from the experiment because their error rate was greater
bodies show no integration between top (waist up) and than 50% or the RTs were 3 SD greater than the mean of
bottom (waist down) halves as a whole. A recent study other subjects, thus there were 37 participants.
(Robbins and Coltheart; 2012) used the same-different
version of composite illusion method for body but not only Stimuli
with horizontal but also vertical body split. They found
The bodies that we used in our experiment were generated
body composite effect, but it was stronger for left and right
by an internet based program (www.modelmydiet.com/).
halves compared to top and bottom halves, and the effects
The program allows generating all kinds of bodies, with
were weaker than for faces. Instead of using identity-based
different gender, face, clothes, hair style, and BMI, thus
approach toward body processing, posture-based approach
each part of the body could have been under control.
was conducted in another study (Willems et al., 2014) to
Varying the BMI allow us to create models with different
investigate human body perception. In contrast to the
shapes. We created ten identities with different hairstyle,
studies mentioned above, (Soria Bauser, Suchan and Daum,
and bikinis. Only female bodies were made. Their faces
2011; Robbins and Coltheart, 2012), computer-generated
were masked and they wore bikinis thus clothes did not
model was used with the same identity, but with different
affect the participant perception. By using this program
postures. Results suggest the evidence that human body
there was a chance to generate models, and varying their
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BMI thus the body shape was the merely variable that could Design and Procedure
affected the participants’ responses. Each identity had a
Subjects were participated in a computer assisted
thinner (BMI 19) and fatter (BMI 26) version. Altogether 20
experiment. They were seated in front of a 20" monitor, and
bodies were made. The same identity model different
they could give their response by using two keyboard
versions (thinner or fatter) were paired together; either the
bottoms. The program was designed with DmDx. The
fatter version was on the top, or the thinner one. Taking
subjects participated in four trials in random order; body
together 40 body stimulus were made, which were all
upright, body inverted, face upright, face inverted. They
aligned and upright. The aligned version of the body was
were instructed to use the central as a fixation point. Halved
made by cutting it half horizontally across the waist by a
bodies or a faces were seen for 400ms, after a scrambled
white thin line. The misaligned version of the body was
mask for 200ms, and following a halved body or face. The
made by shifting the lower part of the body right. All the
participants’ task was to response whether the two pictures’
aligned version stimuli had a misaligned version. Plus all
top halves were same or different. If it was same they
the aligned and misaligned stimulus had an inverted version,
pressed L, if it was different they pressed A. The procedure
thus 120 body stimulus were made (Fig. 1). Upright and
could be seen in Fig. 3.
inverted conditions were separated.
The faces were chosen from the University of Pécs
Institute of Psychology computer's database 10 faces were
used, which ones were cut over therefore merely the inner
parts of the face could be seen. Similar like Soria Bauser,
Suchan and Daum (2011) study, the faces were not cut half,
but under the nose. The aligned faces were created by
separating the lower face halves by a white line from the
upper face halves. The misaligned version of the faces
created by shifting the lower part of the face right. The faces
were presented aligned or misaligned, upright or inverted.
Upright and inverted conditions were separated.
All stimuli were presented either upright aligned, upright
misaligned, inverted aligned, inverted misaligned, together
120 body, and 120 face stimuli were made. The stimuli were
gray-scaled. (See Fig. 1. and Fig. 2.) Figure 2: Illustration of the face stimuli
Figure 3: Experiment design
Results
In line with the other studies (e.g. Reed et al, 2003; Soria
Bauser, Suchan, Daum, 2011), we analysed the performance
differences for the orientation and alignment, in the same
condition. Only correct response reaction times were used,
and the median of the reaction times (RTs) were calculated.
Furthermore, the mean proportions of correct responses
were calculated for each condition. Using the previous
approaches (Soria Bauser, Suchan and Daum, 2011),
efficiency scores were also calculated to obtain an
integrated performance score (mean RT divided by the
proportion of correct responses). Low efficiency scores
indicated better performance. For RT data, we analysed only
Figure 1: Illustration of the body stimuli trials for which the response was correct. Separate repeated
measures of ANOVA were conducted (using Greenhouse-
Geisser corrections) on median RTs data, proportion of
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correct responses and efficiency scores with two stimuli Discussion
category (Body vs. Face) for 2 Orientation: upright vs.
In this study we explored holistic processing for bodies and
inverted) x 2 Alignment (Aligned vs. Misaligned) in
for faces using composite effect. The evidence for body
accordance with previous studies (Soria Bauser, Suchan and
holistic processing is coming from inversion effect (Tanaka
Daum, 2011; Robbins and Coltheart, 2012; Willems et al.,
and Farah, 1993; Reed et al., 2003; Reed et al., 2006).
2014; McKone et al., 2013). The results are presented in
Findings of previous studies using composite effect to
Fig. 4.
explore body holistic processing are mixed (Soria Bauser,
Suchan and Daum, 2011; Robbins and Coltheart, 2012). The
Face stimuli
holistic processing occurs when performance is better for
Repeated measures ANOVA for reaction time yielded main misaligned stimuli, since in aligned condition it became
effect of Alignment (F(1, 36)=7.58 p<.01). Reaction time difficult to separate the top half from the bottom half. In
was significantly faster for misaligned faces compared to case of faces the result are clear; subjects are slower and less
aligned faces. There was interaction between Alignment and accurate in recognizing the top half of the face when it is
Orientation (F(1,36)=7.88 p<.01), which means participants aligned compared to misaligned condition when the bottom
were faster in case of upright misaligned faces, compared to half of the face is created by shifting the lower part of the
upright aligned faces, whereas in case of inverted faces, this face right, thus faces perception is holistic (de Heering,
difference cannot be observed. Wallis and Maurer, 2012; Rossion and Boremanse, 2008).
Analysis of accuracy yielded interaction of Alignment We meet faces and bodies frequently, therefore we become
and Orientation (F(1, 36)=6.6 p <.05). Performance was experts in body and face processing, and additionally we
better for misaligned faces compared to aligned faces when perceive them together (Reed et al., 2003). The aim was to
they were presented upright, while there was no difference investigate whether human body shape perception shares the
in performance for inverted faces (aligned-misaligned). same process used for face perception.
Significant main effect of Alignment (F(1,36)=3.8 p<.05) Consistent with previous results (Young, Hellawell and
was observed for efficiency scores, which means Hay, 1987; Rossion and Boremanse, 2008; Soria Bauser,
performance was better for misaligned faces compared with Suchan and Daum, 2011; McKone et al., 2013), we
aligned faces. Additionally, there was interaction between observed composite illusion for faces as reaction time was
Alignment and Orientation (F(1,36)= 7,46 p<.01), significantly faster for upright misaligned faces compared to
suggesting that participants were more efficient for upright upright aligned faces. Also performance was better and
misaligned faces, compared to aligned faces, although this more efficient for upright misaligned faces compared to
difference disappears with inverted faces. None of the other upright aligned faces. In the case of inverted faces, there
analyses reached significance for faces stimuli. was no difference between misaligned and aligned stimuli.
Our results confirm holistic processing for faces; we process
Body stimuli face stimuli as a gestalt, thus for participants it was hard to
Repeated measures ANOVA for reaction time yielded main name whose faces they saw when the top and the bottom
effect of Alignment (F(1, 36)=13.6; p<.01), and Orientation half of the face were aligned. Nevertheless, misalignment
(F(1,36)=4.25; p<.05). Participants were faster in made them faster and their performance better and more
misaligned bodies compared to aligned bodies. efficient. No composite effect was observed for inverted
Additionally, the effect was stronger for inverted bodies stimuli.
compared to upright bodies. In a typical inverted face perception condition reaction
Analysis of accuracy yielded main effect of Alignment time increases and performance decreases, which indicate
(F(1, 36) = 6.02; p<.05). Performance was more accurate for the inversion effect (Tanaka and Farah, 1993; Reed et al.,
misaligned bodies compared to aligned bodies. Furthermore, 2003; Reed et al., 2006). In our experiment, participants
we found significant interaction for Orientation and showed similar tendency, as they were slower when inverted
Alignment (F(1, 36)= 5.7 p<.05). Participants performed faces were presented, but the effect could not be observed in
better for inverted misaligned bodies than inverted aligned their performance and efficiency scores.
bodies, whereas there was no difference in performance for Our results seem affirmative for body composite effect,
upright aligned and upright misaligned bodies. however merely inverted. Participants were faster and had
Efficiency scores analysis revealed main effect of better performance and were more efficient for inverted
Alignment (F(1, 36)= 10.7 p<.01). Performance was more misaligned bodies compared to inverted aligned bodies,
accurate for misaligned bodies compared to aligned bodies. which reveals composite illusion. In the case of upright
Furthermore, significant interaction for Orientation x bodies no composite illusion could be observed, since there
Alignment (F(1, 36)= 6.65 p<.05) appeared. Performance was no difference in performance between upright aligned
was better for inverted misaligned bodies compared to bodies and upright misaligned bodies. Results are contrary
inverted aligned bodies, whereas there was no difference in to Soria Bauser, Suchan and Daum (2011) findings, because
performance for upright misaligned bodies compared with they could not be observed difference between aligned and
upright aligned bodies. None of the other analyses reached misaligned conditions. Our findings partly confirm Robbins
significance for faces stimuli. and Coltheart’s (2012) results, but they did not demonstrate
120
Figure 4: Results
composite effect inverted, when bodies were halved their reaction times were slower for inverted bodies
horizontally, although left and right halves showed inverted compared to upright bodies. Results support that inversion
composite effect. did not affect the performance, which reveals that the
Two explanations could be interpreted, for inverted body configural spatial relations were not disrupted by the
composite effect, which are related to each other. One is that inversion and the alignment. Thus, subjects performed
body processing is based on first-order relational significantly better for inverted misaligned condition
information, which provides a spatial map among body compared to inverted aligned condition, which reveals
parts and supported by inversion effect for several body composite illusion for inverted body shapes. The other
postures (Reed et al, 2006). As seen in Fig. 1 in upright possible explanation for inverted body composite effect is
misaligned condition, the first-order relational information that we have learned how bodies look like because we meet
of the body is not compounded. This could influence that them frequently, therefore we become experts (Reed et al.,
subjects performed the same for upright misaligned 2003). That is why in upright condition misalignment did
condition compared to upright aligned condition. In inverted not affect the result, because despite the gap between the
condition, the body’s configural spatial relations are two body halves and the misalignment, participants still
disrupted by the inversion (Reed et al, 2006). In our study perceived the stimuli holistically. The true composite effect
participants performed almost the same in accuracy and could be observed with respect to inverted images. This is
efficacy scores in inverted misaligned condition compared partly due to holistical processing and partly because of the
to upright aligned or misaligned conditions; additionally, fact that inversion disrupted perception; with both factors
121
leading to worse performance in inverted aligned body, S., Broughton, M., and Fernando, D. (2013) Importance
compared to inverted misaligned body. To support this of the inverted control in measuring holistic face
hypothesis more information is needed. We suggest processing with the composite effect and part-whole
conducting the same study with children participants, since effect. Frontiers in Psychology: PerceptionScience, 4
children may not be experts on body shapes, compared to (33), 1-21.
adults like adults do. Robbins, R. A., and Coltheart, M. (2012). Left-right holistic
This study is the first, as far as we are concerned, which integration of human bodies. Quarterly Journal of
investigated body composite effect using computer Experimental Psychology, 65, 1962-1974.
generalized bodies with different BMI. Previous studies Reed, C. L., Stone, V. E., Grubb, J. D., and McGoldrick, J.
used pictures of males or females (Soria Bauser, Suchan and E. (2006). Turning configural processing upside down:
Daum, 2011; Robbins and Coltheart, 2012) or Willems et Part and whole body postures. Journal of Experimental
al., (2014) used computer generalized bodies to investigate Psychology, Human Perceptual Perform, 32, 73–87.
whether there is a composite effect for body postures. Using Reed, C. L., Stone, V., Bozova, S., and Tanaka, J. (2003).
this method, perception was only affected by body shape, The body inversion effect. Psychological Science, 14,
because the models that had to be compared had the same 302–308.
identity, merely their BMI differentiated. Rossion, B., and Boremanse, A. (2008). Nonlinear
Taken together, the subjects perceived the face relationship between holistic processing of individual
holistically, that is why they were slower and less accurate faces and picture-plane rotation: Evidence from the face
and efficient in upright aligned condition. Furthermore, composite illusion. Journal of Vision, 8, 3-13.
inverted presentation affected the holistic processing, and Slaughter, V., Stone, V.E., Reed, C. (2004) Perception of
composite effect could not be observed for inverted faces. Faces and Bodies. American Psychological Society, 13
Body composite effect was revealed but merely for inverted (6), 219-223.
stimuli. In upright condition there was no difference Tanaka, J.W. and Farah, M.J. (1993) Parts and wholes in
between misaligned and aligned conditions. face recognition. The Quarterly Journal of Experimental
Psychology, 46a, 225–245.
Conclusion Young, A. W., Hellawell, D., and Hay, D. C. (1987).
In this study the aim was to explore body holistic processing Configurational information in face perception.
by composite illusion. There is little knowledge about Perception, 16, 747–759. Abstract retrieved from:
human body shape processing. Additionally, this research is PubMed Item: 3454432
the first that studies body processing with computer Willems, S., Vrancken, L., Germeys, F., and Verfaille, K.
generalized body shapes varying BMI. Body processing (2014). Holistic processing of human body postures:
looks similar to face processing, thus there are similarities evidence from the composite effect. Frontiers in
and differences as well (Slaughter, Stone and Reed, 2004). Psychology, 5, 1-9.
In our study composite illusion was supported for human
body forms, but merely when they were presented in an
invertedly. More research is needed in this field, because
previous results are mixed, and our study has brought up
even more questions.
Acknowledgments
This research was supported by OTKA (PD – 109597)
research grant.
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