ArticlePDF Available

Abstract and Figures

Research on the processing of sexual stimuli has proved that such material has high priority in human cognition. Yet, although sex differences in response to sexual stimuli were extensively discussed in the literature, sexual orientation was given relatively little consideration, and material suitable for relevant research is difficult to come by. With this in mind, we present a collection of 200 erotic images, accompanied by their self-report ratings of emotional valence and arousal by homo- and heterosexual males and females (n = 80, divided into four equal-sized subsamples). The collection complements the Nencki Affective Picture System (NAPS) and is intended to be used as stimulus material in experimental research. The erotic images are divided into five categories, depending on their content: opposite-sex couple (50), male couple (50), female couple (50), male (25) and female (25). Additional 100 control images from the NAPS depicting people in a non-erotic context were also used in the study. We showed that recipient sex and sexual orientation strongly influenced the evaluation of erotic content. Thus, comparisons of valence and arousal ratings in different subject groups will help researchers select stimuli set for the purpose of various experimental designs. To facilitate the use of the dataset, we provide an on-line tool, which allows the user to browse the images interactively and select proper stimuli on the basis of several parameters. The NAPS ERO image collection together with the data are available to the scientific community for non-commercial use at
Content may be subject to copyright.
published: 10 September 2015
doi: 10.3389/fpsyg.2015.01336
Frontiers in Psychology | 1 S
eptember 2015 | Volume 6 | Article 1336
Edited by:
Luiz Pessoa,
University of Maryland, USA
Reviewed by:
Jan Van Den Stock,
KU Leuven, Belgium
Desmond Jay Oathes,
Stanford University, USA
Małgorzata Wierzba and Artur
Laboratory of Brain Imaging,
Neurobiology Centre, Nencki Institute
of Experimental Biology, 3 Pasteura
Street, Warsaw 02-093, Poland;
Specialty section:
This article was submitted to
Emotion Science,
a section of the journal
Frontiers in Psychology
Received: 27 March 2015
Accepted: 19 August 2015
Published: 10 September 2015
Wierzba M, Riegel M, Pucz A,
sniewska Z, Dragan WŁ, Gola M,
Jednoróg K and Marchewka A (2015)
Erotic subset for the Nencki Affective
Picture System (NAPS ERO):
cross-sexual comparison study.
Front. Psychol. 6:1336.
doi: 10.3389/fpsyg.2015.01336
Erotic subset for the Nencki Affective
Picture System (NAPS ERO):
cross-sexual comparison study
Małgorzata Wierzba
, Monika Riegel
, Anna Pucz
, Zuzanna Le
Wojciech Ł. Dragan
, Mateusz Gola
3, 4
, Katarzyna Jednoróg
and Artur Marchewka
Laboratory of Brain Imaging, Neurobiology Centre, Nencki Institute of Experimental Biology, Warsaw, Poland,
Faculty of
Psychology, University of Warsaw, Warsaw, Poland,
Institute of Psychology, Polish Academy of Sciences, Warsaw, Poland,
Swartz Center for Computational Neuroscience, Institute for Neural Computations, University of California, San Diego,
San Diego, CA, USA,
Laboratory of Psychophysiology, Department of N europhysiology, Nencki Institute of Experimental
Biology, Warsaw, Poland
Research on the processing of sexual stimuli has proved that such material has high
priority in human cognition. Yet, although sex differences in response to sexual stimuli
were extensively discussed in the literature, sexual orientation was given relatively little
consideration, and material suitable for relevant research is difficult to come by. With this
in mind, we present a collection of 200 erotic images, accompanied by their self-report
ratings of emotional valence and arousal by homo- and heterosexual males and females
(n = 80, divided into four equal-sized subsamples). The collection complements the
Nencki Affective Picture System (NAPS) and is intended to be used as stimulus material
in experimental research. The erotic images are divided into five categories, depending
on their content: opposite-sex couple (50), male couple (50), female couple (50), male
(25) and female (25). Additional 100 control images from the NAPS depicting people in a
non-erotic context were also used in the study. We showed that recipient sex and sexual
orientation strongly influenced the evaluation of erotic content. Thus, comparisons of
valence and arousal ratings in different subject groups will help researchers select stimuli
set for the purpose of various experimental designs. To facilitate the use of the dataset,
we provide an on-line tool, which allows the user to browse the images interactively and
select proper stimuli on the basis of several parameters. The NAPS ERO image collection
together with the data are available to the scientific community for non-commercial use
Keywords: emotion, erotic stimuli, homosexual, heterosexual, sexual orientation, Nencki Affective Picture System
Sex is one of the most important driving forces in human life, yet very little has been uncovered
about its mysteries (Georgiadis and Kringelb ach, 2012). Undoubtedly, sexual behavior is crucial for
reproduction and thus may be viewed as the primary and fundamental mechanism of survival of
the species (Costumero et al., 2013). This, however, constitutes only a small part—perhaps even the
least interesting one—of what there is to explore about sex. With all its diverse manifestations,
human sexual behavior abounds in practices that do not serve reproduction (Georgiadis and
ringelbach, 2012) and there is hardly any sexual activity, no matter how elabora
te or bizarre, that
Wierzba et al. NAPS ERO: erotic pictures database
could not be considered a potential source of sexual pleasure
(Lewontin, 2000). The complexity of human sexuality is a
classic example of the interplay of nature and nurture, whereby
inherited, biologic ally determined mechanisms interact with
cultural and environmental factors (
LeVay, 1993; Georgiadis and
Kringelbach, 2012).
With this conceptual framework, many manifestations of
sexual arousal—defined as physical or psychological readiness
to engage in sexual behavior (Stoléru et al., 2012; Costumero
et al., 2013)—may be proposed: from vague and intangible sexual
desire or attraction to observable, physiological genital response.
Classically, this ambiguity was overcome in research on sexuality
by simultaneously measuring subjective sexua l experience (self-
report) and using penile or vaginal photoplethysmography
techniques (Freund, 1963; Rieger et al., 2015). Both methods
were criticized for serious limitations they impose on research.
Whereas self-report measures of sexual behavior were frequently
considered unreliable and prone to inaccuracy and deception
Lewontin, 2000), peripheral response measurements such as
photoplethysmography were regarded as relatively intrusive and
largely ineffective (Ponseti et al., 2009).
More recently, sexuality became the subject of neuroimaging
research (for a review see: Georgiadis and Kringelbach, 2012;
Stoléru et al., 2012). As psychophysiological response to
sexual stimulation begins in the brain, neuroimaging methods
could emerge as the most effective in exploring sexual
arousal. In fact, it has been shown that the human brain is
involved in all phases of the human sexual response cycle:
from evoking arousal through consummation and orgasm to
satiation (Georgiadis and Kringelb ach, 201 2). To date a number
of neural structures underlying different aspects of sexual
response have been identified, among which the following were
mentioned: amygdala, midbrain, hippocampus, orbitofrontal
cortex, nucleus accumbens, subcallosal cortex, ventral anterior
cingulate, mediodorsal thalamic nucleus, hypothalamus and
visual cortex (Safron et al., 2007; Stoléru et al., 2012; Sylva et al.,
2013). The implication of this vast network of structures is still
being explored and different functional roles were proposed to
explain their contribution to sexual behavior (Sylva et al., 2013).
Yet, it remains uncertain whether there is anything unique and
exceptional about functional neuroanatomy of sex t hat would
differentiate it from other pleasures (
Georgiadis and Kringelbach,
Most obviously, the idea of sexual pleasure that would be
the same to everyone irrespective of individual differences is
quite abstract (Georgiadis and Kringelbach, 2012). Indeed, in
various kinds of sexual responses, significant differences between
men and women were observed (Rupp and Wallen, 2008,
2009; Stoléru et al., 2012; Sylva et al., 2013). In particular,
as demonstrated by subjective self-report and genital response
measurements (Chivers et al., 2004; Bailey, 2009; Rupp and
Wallen, 2009), as well as in neuroimaging research (Safron et al.,
2007; Sylva et al., 2013), male sexual arousal patterns are category
specific, i.e., men experience sexual arousal when exposed to
preferred-sex stimuli and little or no arousal to other sexual
stimuli. By contrast, women’s sexual arousal patterns are less
differentiated, as t h ey tend to show similar response to sexual
stimuli irrespective of the preferred-sex or non-preferred-sex
Research on sexual arousal largely focused on male
participants, which is especially evident in the neuroscientific
domain (
Stoléru et al., 2012; Sylva et al., 2013). Relatively few
attempts were made to compare female and male participants by
means of neuroimaging and t he findings were rather ambiguous
(Gizewski et al., 2006; Sylva et al., 2013). Although there is
evidence that t he patterns of neural activation in men and
women are similar, differences in the intensity of neural response
were shown to exist. In particular, women revealed relatively
less activation in some brain regions involved in sexual arousal,
including amygdala a nd hypothalamus (Karama et al., 2002;
Hamann et al., 2004).
Only recently neuroimaging studies have begun to examine
sexual response in the context of sexual orientation (Savic
et al., 2005; Berglund et al., 2006; Kranz and Ishai, 2006;
Ponseti et al., 2006, 2009; Safron et al., 2007; Hu et al., 2008,
2011; Paul et al., 2008; Savic and Lindström, 2008; Zhang
et al., 2 011; Sylva et al., 2013
). Most evidence collected so
far points to similarities between homosexual a nd heterosexual
response patterns to sexual stimulation. In particular, category
specificity in arousal is characteristic of men irrespective of
their sexual orientation. When sexual stimuli matched the
participant’s stated preference, increased activity across multiple
brain regions was observed that generally did not differ with
sexual orientation (Safron et a l., 2007; Sylva et al., 2013).
Although differences in several brain regions were reported,
including: amygdala (
Safron et al., 2007), nucleus accumbens,
extrastriate, hypothalamus, and thalamus (Sylva et al., 2013),
these differences were mostly marginally significant and did not
survive controlling for multiple comparisons. On the other hand,
Ponseti et al. (2006) reported brain activation driven by sexual
preference, independent of either subject’s sex or the stimulus.
Moreover, it was demonstrated that brain response patterns to
sexual stimuli contained sufficient information to predict sexual
preference with high accuracy (Ponseti et al., 2009).
Interpretation of differences due to sex and sexual orientation
remains a challenge, especially if the stimuli used in experimental
research are not properly controlled (Rupp and Wallen, 2009). It
is uncertain whether t h e observed differences represent different
ways of arousal processing or merely different levels of arousal
associated with the stimuli (
Safron et al., 2007). As previous
findings suggested, men and women’s interest in and response
to visual sexual stimuli may be dependent upon the activities
and situations depicted (Rupp and Wallen, 2009). Thus, in
order to dissociate the influence of sex from that of sexual
orientation it is necessary to perform counter-balanced studies
involving different t ypes of experiment al material that appeals to
different groups of subjects—male and female, homosexual, and
heterosexual—at a comparable level.
To date, different modalities of stimuli were used to trig ger
sexual response. The most common included visual cues, usually
either still images or films (for an extensive review see: Stoléru
et al., 2012
). Attempts were also made to use other types of
stimuli: verbal (e.g., Stevenson et al., 2011), auditory, i.e., erotic
audio content or erotic prosody (e.g.,
Ethofer et al., 2007),
Frontiers in Psychology | 2 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
olfactory, i.e., (artificial) pheromones (e.g., Savic et al., 2005;
Berglund et al., 2006, 2008; Savic and Lindström, 2008), or
somatosensory, i.e., penile or clitoral stimulation (e.g., Holstege
et al., 2003; Georgiadis and Holstege, 2005; Georgiadis et al., 2006,
Different strategies were applied to the selection of stimuli and
the description of thi s process was usually relatively imprecise.
The stimuli used in sexual research most often included the
depictions of opposite-sex intercourse or interactions, as well as
male and female nudes (Stoléru et al., 2012). Limited number
of studies used same-sex intercourse or interactions as sexual
stimuli (e.g., Safron et al., 2007; Paul et al., 2 008; Hu et al.,
2008, 2011; Zhang et al., 2011; Sylva et al., 2013). Usually the
stimuli were preselected to elicit comparable levels of perceived
sexual arousal or sexual attractiveness (Stoléru et al., 2012). Other
subjective measures controlled for included: emotional valence
and emotional arousal (e.g.,
Ponseti et al., 2006; Jacob et al., 2011),
emotional intensity (e.g., Walter et al., 2008), pleasantness (e.g.,
Savic et al., 2005; Berglund et al., 2006), or perceived erection
(e.g., Arnow et al., 2002; Moulier et al., 2006; Mouras et al.,
2008). However, the validity of these subjective measures was—
with some notable exceptions—mostly based on the author’s a
priori evaluation or the opinions of a very small number of
independent judges. In fact, e ven in the most recent research
the selection of sexual stimuli was constrained by the lack of
adequately validated experimental material (e.g., Sescousse et al.,
2010, 2013; Demos et al., 2012; Kühn and Gallinat, 2014; Voon
et al., 2014). Finally, efforts to provide arousing sexual stimuli for
use by other researchers were rather limited (
Lang et al., 2008;
Rupp and Wallen, 2009; Jacob et al., 2011).
One of the most commonly recognized sources of
standardized visual affective stimuli is the I nternational Affective
Picture System (IAPS; Lang et al., 2008). This database provides
pictorial material from a wide range of content categories,
including a limited number of sexual stimuli. However, since the
original IAPS pictures were collected several decades ago, the
sexual stimuli in this dataset are now considered obsolete and
inadequate for experimental research (Jacob et al., 2011).
Recently, Jacob et al. (2011) introduced a set of 100 erotic
pictures to complement the IAPS database. In this study ratings
of 20 erotic stimuli from IAPS and 100 new erotic stimuli were
collected and made available to rese a rchers. Since the set was
intended for research with female subjects, two different picture
categories were defined: heterosexual couples in intimate or
erotic interaction (not sexually explicit); attractive single males
(not sexually explicit, i.e., no genitals were depicted). Similarly
to the IAPS, the stimuli colle ct ed by
Jacob et al. (2011) were
rated with regard to valence, arousal and dominance using Self-
Assessment Manikin (SAM, Bradley and Lang, 1994) scales.
The authors, however, focused on non-explicit sexual scenes,
considered suitable for research on intimacy and attachment.
Moreover, the set was only validated on heterosexual females,
which significantly limits its usefulness for research on other
Another set of stimuli was introduced by
Rupp and Wallen
(2009). In this study, a set of 216 sexually explicit photographs
of heterosexual couples was viewed and rated with regard to
sexual attractiveness by heterosexual subjects (men, women
not using hormonal contraception, women using hormonal
contraception). The set was divided into several categories
depicting different sexual activities (oral sex to male, oral sex
to female, female dominant intercourse facing male partner,
female dominant intercourse facing away from male partner,
male dominant intercourse from front of female partner, male
dominant intercourse from behind female partner). Although it
was not the primary aim of
Rupp and Wallen (2009) to create a
standardized database of stimuli, the pictures used in their study,
together with attractiveness ratings, are available on request. This
material, however, is suitable only for research on heterosexuals.
As outlined above, sexual stimuli currently used in research
vary substantially and attempts to provide suitable standardized
material were unsatisfactory. Moreover, since the vast majority
of research on the processing of sexual stimuli investigated sex
differences in heterosexual subjects, no stimuli appropriate for
studying sexual responses of non-heterosexuals (homosexuals,
bisexuals, etc.) have been provided and validated. Finally, images
used as sexual stimuli are often not fully specified and their
technical parameters are not controlled in experimental setting.
Such technical features are known to influence the processing
of images and hence should be considered in the process of
stimuli selection (
Knebel et al., 2008; Willenbockel et al., 2010).
Controlling for low-level features of an image was pointed out
as an important issue in a variety of me asuring methods, such
as eye-tracking, functional magnetic resonance imaging (fMRI),
magnetoencephalography (MEG), and electroencephalography
(EEG) (Willenbockel et al., 2010).
The erotic subset of the Nencki Affective Picture System
(NAPS ERO) is designed to address some of these limitations.
This collection of images was selected to represent a wide
range of content applicable in research on subjects of different
sex and sexual orientation. In the process of selecting erotic
images, we were primarily interested in images derived from non-
professional collections, depicting sexual content in a natural
manner. The subset contains images depicting same-sex and
opposite-sex couples engaged in different kinds of sexual contact,
as well as individuals sexually appealing to recipients of different
sexual orientati on.
The NAPS ERO dataset consists of standardized sexual
images, as well as commonly used normative ratings of valence
and arous a l. Additionally, several image characteristics were
computed to provide meta-data (width, height, luminance,
contrast, complexity, entropy, and color composition) allowing
for the sele ct ion of physically matching stimuli. The subjects
invited to rate the images (males and females) were selected to
represent extreme orientation toward either homosexuality or
heterosexuality, to best distinguish the stimuli that specifically
appeal to t he respective groups.
The following issues will be explored: (1) Overv iew of the
NAPS ERO set: A broad characteristics of the distribution of
the NAPS ERO ratings is provided, together with meta-data
(physical properties of the images); (2) Influence of sex and
sexual orientation on the preferred category of sexual stimuli:
Normative ratings corresponding to respective content categories
were compared and preferred categories for each group of
Frontiers in Psychology | 3 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
subjects: homosexual males (HoM), homosexual females (HoF ),
heterosexual males (HeM) and heterosexual females (HeF) were
identified; (3) Influence of sex and sexual orientation on individual
image evaluations: Stimuli that best differentiate between the
HoM, HoF, HeM, and HeF groups are identified by means of
statistical tests performed on ratings of individual images; this
provides additional guidance for the use of the NAPS ERO
We hypot hesized that NAPS ERO ratings would allow to
differentiate stimuli perceived as preferable (i.e., positive in
valence and highly arousing) to each of the compared groups. In
particular, we expected that HoM would find images depicting
males and male couples as most appealing. HoF were expected
to prefer pictures of females and female couples. We predicted
that images of females, female couples and opposite-sex couples
would be sexually appealing to HeM. As for HeF, we assumed
that most preferable images would be t h ose depicting males and
opposite-sex couples.
The NAPS ERO dataset is freely available for research
community, so as to ensure a certain level of standardization
across studies using sexual visual stimuli and facilitate
experimental research.
Materials and Methods
The NAPS ERO subset consists of 200 erotic images initially
divided into the following content categories: Opposite-sex
Couple (50 pictures), Male Couple (50), Female Couple
(50), Male (25), and Female (25). The Opposite-sex Couple,
Male Couple and Female Couple categories contain images
of opposite-sex, male same-sex and female same-sex couples
respectively, explicitly engaged in sexual intercourse or sexual
interaction. The Male category contains photographs depicting
male individuals, and the Female category—female individuals
in an erotic, sexual setting. Examples of erotic pictures from each
category are presented in Figure 1.
The erotic pictures were obtained from Flickr (https://www., an image hosting Internet service. From the initial
pool of nearly 1000 images, 200 were selected to represent a
diversity of sexual content. Six independent judges (3 females, 3
males) participated in the selection process by assigning images to
above-mentioned content categories. The judges were provided
with a brief summary of the purpose of the selection process,
as well as t h e description of the categories. Only pictures for
which full agreement of the judges was reached were included in
the set. Selected pictures were either under a Creative Commons
license ( or used with
a written permission of the authors.
The selected images were colorful photographs, resized to
match the resolution of 1600 × 1200 (landscape) or 1200 × 1600
(portrait) pixels. All th e images were inspected with regard to
technical parameters (e.g., resolution, color, contrast, brightness)
and adjusted if necessary. Images containing visible commercial
logotypes or inscriptions were edited.
For each image we computed its technical parameters using
the Python Image Library (PIL, version 1.1.7; Python version
2.7.3). Similarly to other NAPS images, the following parameters
are provided: width, heig h t , luminance, contrast, complexity
(JPEG compression rate), entropy, and color composition (CIE
Additionally, 100 control images depicting people in non-
erotic context were selected from the NAPS People (50 pictures)
and Faces (50 pictures) categories. The control stimuli were
chosen to evenly represent the valence-arousal affective space
based on the normative ratings from the NAPS (
Marchewka et al.,
Sexual Orientation Questionnaires
The sexual orientation of t h e subjects was assessed with the
Kinsey Scale (
Kinsey et al., 1948/1998) and the Sell Assessment
of Sexual Orientation (Sell, 2007) questionnaire. Although the
Kinsey Scale is the most widely used instrument, it only
allows for a very general des cription of sexual identity. Several
shortcomings related to the use of the Kinsey Scale have
been pointed out (Sell, 2007). The Sell Assessment of Sexual
Orientation, on the other hand, provides much more precise
information on sexual preferences and behaviors, enabling the
determination of several aspects of sexual orientation (Sell,
2007). Since the questionnaires were not available in Polish,
the Kinsey Scale, the Sell Assessment of Sexual Orientation and
the Kinsey-type measures of sexual attractions, sexual contact
and sexual orientation identity were translated into Polish (3
FIGURE 1 | A sample image from each category. All images were obtained from Flickr and were published under a Creative Commons license. Credits
(from left to right): Charles Roffey, CC BY-N C- SA 2.0; David Shankbone, CC BY 2.0; Georgie Pauwels, CC BY 2.0; Charles Roffey, CC BY-NC-SA 2.0; Lies
Thru a Lens, CC BY 2.0. For license terms see: CC BY 2.0 (; C C BY-NC-SA 2.0 (
Frontiers in Psychology | 4 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
independent translators) and back-translated (1 translator) to
confirm the accuracy of the translation. The Polish versions of
the questionnaires can be found in the Supplementary Materials.
A total of 80 subjects aged 18–35: 40 homosexual (20 F, 2 0
M; age: M = 23.7, SD = 4.0) and 40 heterosexual (20 F,
20 M; age: M = 22.3, SD = 2.3) were invited to rate the
images. Most of the participants were college students or young
graduates from various faculties and departments (including
management, social sciences, philology, biology, medicine, as
well as technical faculties) of several universities and schools in
Warsaw. Several recruitment channels were used, including mass
mailings arranged by student unions, non-profit organizations
supporting non-heterosexual minorities, as well as social media
and personal communication.
Before they participated in the study, subjects completed
a short on-line screening questionnaire to assess their sexual
orientation wit h the Kinsey-type measures (
Sell, 2007). Only
individuals who manifested extreme orientation toward either
homosexuality (i.e., exclusively homosexual or predominately
homosexual, only incidentally heterosexual) or heterosexuality
(i.e., exclusively heterosexual or predominate ly heterosexual, only
incidentally homosexual) with respect to sexual attractions, sexual
contact and sexual orientation identity were invited to participate
in the study. After the rating procedure, the initial assignment to
particular experimental groups was further confirmed with the
Kinsey Scale (Kinsey et al., 1948/1998) and the Sell Assessment
of Sexual Orientation (
Sell, 2007) questionnaires. The above
inclusion criteria were imposed by the primary aim of the present
study, i.e., to provide a standardized set of sexual stimuli for use
in experimental research and to facilitate the selection of stimuli
with the desired effect on subjects of a given sex and sexual
Subjects received a financial gratification for their
participation in the amount of PLN 30 (approximately EUR 7).
The local research ethics committee of the University of Warsaw
approved the experimental protocol of the study. A written
consent was obtained from each participant and the possibility
to quit the experiment at any point without stating reasons was
During the assessment procedure each subje c t worked on a
separate computer station equipped wit h a standard mouse. A
web application running on a local server was used to collect the
normative ratings. No time constraints to complete the task were
introduced, but an obligatory short break was scheduled. Each
session lasted approximately 60 min.
Each participant was presented with each of the 300 pictures.
The stimuli were divided and randomized within equal-sized
(50 images each) categories: Opposite-sex Couple, Male Couple,
Female Couple, Male + Female, Faces, and People. Then the
stimuli were grouped into blocks consisting of exactly one picture
from each of the six categories. The order of the pictures within
the block was randomized, while ensuring that no consecutive
stimuli belonged to the same content category.
The assessment task was preceded by brief instructions.
Subjects were able to return to the instruction screen or ask
for assistance when in doubt. The full text of the instructions
in Polish and its English translation are enclosed in the
Supplementary Materials.
The images were assessed one at a time. A single picture in
full-screen mode was displayed for 3 s, and then presented in a
smaller size in the left part of the screen along with the valence
and arousal 9-point SAM (
Bradley and Lang, 1994) rating scales.
Additionally, semantic labels describing the scales were used. The
valence scale ranged from 1—this picture elicits very negative
emotions in me, to 9—this picture elicits very positive emotions
in me. The arousal scale ranged from 1—I feel weak emotions, I
am not emotionally aroused, to 9—I feel strong emotions, I am
emotionally aroused. Subjects were encouraged to indicate their
immediate, spontaneous reaction to images. As soon as an image
was rat ed on both scales, the next screen with the subsequent
image was displayed.
Overview of the NAPS ERO Set
Each picture in the NAPS ERO set was rated by 80
subjects, subdivided into equal-sized samples: homosexual males
(HoM), homosexual females (HoF), heterosexual males (HeM),
heterosexual females (HeF). Mean (M) and standard deviation
(SD) of valence and arousal ratings were calculated for each image
and each sample separately. The complete listing of subjective
ratings and technical parameters (width, height, luminance,
contrast, complexity, entropy, and color composition) of
all NAPS ERO stimuli can be found in Supplementary
The distribution of the mean ratings of the NAPS ERO images
in the valence-arousal affective space is presented in Figure 2.
For each group of subjects, a similar curviline a r pattern of
distribution emerged, i.e., stimuli rated as extreme in valence
were a t the same time rated as highly arousing, whereas neutral
stimuli were rated as unarousing.
Erotic content was mostly rated as positive by all the groups
of subjects, except HeM. The latter identified many of the
erotic pictures as negative, especially those depicting males
and male couples. For the members of each group of subjects
preferable (i.e., positive in valence and highly arousing) erotic
stimuli were identified. Most of the pictures preferred by HoM
turned out to represent males or male couples. HoF, on the
other hand, preferred photographs depic ting females and female
couples. HeM also gave high ratings to many photographs
depicting females and female couples, as well as to opposite-
sex couples. HeF singled out pictures of opposite-sex couples
as particularly positive and arousing. However, HeF preference
for any specific type of erotic content appeared to be least
Sex and Sexual Orientation Differences: Image
As outlined in the previous section, members of each group
found some type of erotic content to be preferable in terms of
Frontiers in Psychology | 5 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
FIGURE 2 | Distribution of the mean ratings obtained for 200 erotic images from NAPS ERO and 100 control non-erotic images from NAPS in the
affective space of valence and arousal. Each plot represents mean ratings obtained from a different group of participants.
valence and arousa l. Figure 2 shows that for each group such
preferred sexual stimuli belonged mostly to one or two content
categories. To test the statistical significance of this category
preference, we examined whether the initially defined subsets of
the NAPS ERO collection differed significantly in terms of the
way the pictures were rated by the members of different groups:
Frontiers in Psychology | 6 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
TABLE 1 | Descriptive statistics (M—mean, SD—standard deviation) in the NAPS ERO calculated for valence (Val) and arousal (Aro) in homosexual
females (HoF), homosexual males (HoM), heterosexual females (HeF), and heterosexual males (HeM) for each content category.
Category HoF HoM HeF HeM
Val Aro Val Aro Val Aro Val Aro
Non-erotic (n = 100) M 4.13 3.79 4.48 3.97 4.49 4.61 4.63 4.13
SD 1.85 1.10 1.73 1.31 1.98 1.18 1.47 1.02
Opposite-sex couple (n = 50) M 5.26 3.17 6.21 3.57 6.55 4.86 5.96 4.40
SD 0.75 0.57 0.53 0.66 0.66 0.61 0.60 0.78
Male couple (n = 50) M 5.13 3.27 6.88 4.84 4.77 4.20 3.47 4.10
SD 0.84 0.52 0.69 0.91 0.64 0.62 0.64 0.84
Female couple (n = 50) M 6.73 4.64 5.75 3.17 5.09 3.97 5.56 4.26
SD 0.79 0.75 0.70 0.51 0.68 0.60 0.80 0.96
Male (n = 25) M 4.39 2.72 6.88 4.96 5.64 4.56 3.91 3.58
SD 0.66 0.53 0.64 0.92 0.71 0.55 0.58 0.68
Female (n = 25) M 6.80 4.96 5.27 2.98 5.46 4.13 6.96 5.48
SD 0.90 0.67 0.54 0.67 0.55 0.54 0.34 0.51
HoM, HoF, HeM, and HeF. The mean ra tings for each picture
category are summarized in Table 1.
First, for each subject we obtained me an valence and
arousal ratings of pictures representing each content category.
Using those mean category ratings, we performed ANOVA
for valence and arousal ratings separately, with group as a
between-subject factor (four levels: HoM, HoF, HeM, HeF) and
content category as a within-subject factor (six levels: Non-
erotic, Opposite-sex Couple, Male Couple, Female Couple, Male,
Female). Since we analyzed the mean category ratings, the
normality assumption was satisfied by the laws of the central limit
With regard to valence ratings, we observed the main effect
of group F
(3, 76)
= 4.22, p < 0.008, η
= 0.14, the main
effect of content category F
(3.84, 292.15)
= 69.70, p < 0.001,
= 0.48, as well as the interaction between these two factors
(11.53, 292.15)
= 38.19, p < 0.000, η
= 0.60. The analysis of
post hoc Bonferroni corrected pairwise comparisons revealed a
significant difference (p = 0.04) in the valence ratings of non-
erotic pictures between HeM (M = 4.63, SD = 1.47) and HoF
(M = 4.13, SD = 1.85). No significant differences in the valence
ratings of non-erotic pictures were observed between other
compared groups. In contrast, valence ratings of erotic pictures
depended strongly on group. The detailed results can be found in
Figure 3.
The main effect of group on arousal ratings was not significant
(3, 76)
= 1.24, p = 0.30, η
= 0.05. Still, arousal ratings
were shown to depend on picture content, with th e main
effect of picture category F
(3.53, 268.57)
= 4.53, p < 0.002,
= 0.06. The interaction effe ct of group and cate gory was
also significant F
(10.60, 268.57)
= 29.46, p < 0.001, η
0.54. The post hoc tests revealed no significant differences in
arousal ratings for non-erotic pictures. Arousal ratings of erotic
pictures depended significa ntly on whether the subject belonged
to HoM, HoF, HeM, or HeF, but these differences appeared
to be less pronounced than those for valence, as indicated in
Figure 3.
Sex and Sexual Orientation Differences:
Individual Images
In the previous section we identified differences in the category
mean ratings suggesting a strong preference for a particular
category of sexual stimuli as dependent on group. However,
the strength of this preference depends essentially on many
characteristics of the given erotic image. In particular, images
rated signific antly different by different groups are potentially
valuable as stimuli in experimental designs focused on sex and
sexual orientati on differences.
To facilitate the use of the mean ratings provided with the
NAPS ERO dataset, we investigated sex and sexual orientation
differences in erotic content evaluations of e ach individual
image. We identified stimuli marked by significant differences
(as shown by ANOVAs and t-tests) and provided the results
of this analysis along with the effect sizes as another set of
indexing parameters, in addition to mean ratings (i.e., Ms and
SDs). It should be noted that the normality assumption was
not met for the tests of individual ratings. Since violations of
the normality assumption generally have rather small effect on
the summary score distribution (e.g.,
Loftus and Loftus, 1988;
Howell, 2013), we present the results obtained from the statistical
tests as approximate parameters to guide the selection process of
the sti muli.
To this end, Two-Way (sex × sexual orientation) ANOVAs
were performed for valence and arousal for each picture
separately to identify those with significant main effect s and
interaction effects on affective evaluation. For both affective
Frontiers in Psychology | 7 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
FIGURE 3 | Pairwise comparisons of image ratings averaged over all subjects in a given group and over all images in a given category. Each comparison
is done separately for valence and arousal. Significant differences (p < 0.05) are marked with an asterisk. Notation: HoM, homosexual males; HoF, homosexual
females; HeM, heterosexual males; HeF, heterosexual females; N, Non-erotic; OC, Opposite-sex Couple; MC, Male Couple; FC, Female Couple; M, Male; F, Female.
dimensions the η
and p-value were provided for each effect:
sex, sexual orientation and sex × sexual orientation interaction.
Moreover, a series of t-tests were performed to distinguish
images that best differentiate between each of the possible
pairs of groups: HoM—HeM, HoM—HoF, HoM—HeF, HeM—
HoF, HeM—HeF, HoF—HeF. The difference of means, Cohen’s
d and p-value were obtained for each variable (valence and
arousal) and each picture in each comparison. Differences in
the means between the respective groups are presented in
Figure 4.
The complete ratings along with the ANOVAs a nd t-tests c an
be accessed online at as an interactive
data browser.
In the present work we introduce the NAPS ERO—a database of
200 erotic images of broad applicability to experimental research
in a wide range of disciplines. The collection includes images
suitable for studies on subjects differing in terms of sex or sexual
orientation. To date, few attempts have been made to standardize
or validate sexual stimuli, the results of which were rather
unsatisfactory for reasons such as obsolescence and paucity of
stimuli (
Lang et al., 2008) or validity confirmed only for specific
populations (
Lang et al., 200 8; Rupp and Wallen, 2009; Jacob
et al., 2011). As a rule, stimuli used to trigger sexual responses
were selected on a priori basis and their properties were rarely
controlled or a dequately described. This variety of experimental
material may have accounted for some of the inconsistencies
between the findings in previous studies, as they might have used
stimuli of unequal interest to the compared groups. Substantial
discrepancies between effect sizes in comparisons of groups
differing in sex or sexual orientation reported in research may be
due to the use of uncontrolled, dissimilar experimental material
(Rupp and Wallen, 2009).
The NAPS ERO dataset provides erotic images together with
their normative ratings of valence and arousal, as well as technical
parameters of the images. Erotic images included in the database
differ in the explicitness of sexual content, providing both
nuanced and highly explicit scenes. Thus, valence and arousal
ratings can be treated as parameters guiding the selection of
stimuli according to the requirements of a given experiment a l
design. Additionally, the NAPS ERO images are divided into
several categories, as such classification has proven useful in
Frontiers in Psychology | 8 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
FIGURE 4 | Differences in the mean ratings between the respective samples (HoM—HeM, HoM—HoF, HoM—HeF, HeM—HoF, HeM—HeF, HoF—HeF)
as obtained for each of the NAPS ERO images (200 erotic, 100 non-erotic), for valence and arousal separately. Each bin represents a difference in the
mean ratings of a given image. Significant differences (p < 0.05) are marked by a darkening of a bin. Bins are sorted according to the size of a difference in mean
ratings. Images rated higher by one group in a given comparison are aggregated on both sides of the plot, whereas images for which no difference was obtained can
be found around the middle of the plot.
Frontiers in Psychology | 9 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
previous research. Since categorizations of sexual stimuli usually
differentiated opposite-sex and same-sex sc enes, as well as male
and female nudes (Stoléru et al., 2012), we decided to adopt
similar labeling and divide the NAPS ERO collection into
Opposite-sex Couple, Male Couple, Female Couple, Male, and
Female content categories.
Another advantage of the NAPS ERO is the possibility of
choosing stimuli according to both sex and sexual orientation
of the subjects. Since previous studies focused mainly on
heterosexual male participants, valid a ted stimuli suitable for
the exploration of sexual mechanisms in different groups are
hard t o come by. Thus, in the NAPS ERO we provide ratings
obtained from four distinct samples strictly controlled for sexual
orientation (
Kinsey et al., 1948/1998; Sell, 2007): h omosexual
males, homosexual females, heterosexual males and heterosexual
females. Our decision to collect ratings only from subjects
manifesting extreme orientation toward either homosexuality or
heterosexuality was imposed by the primary aim of the present
study, i.e., to provide a standardized set of sexual stimuli for
use in experimental research and to most reliably detect those
features of the stimuli t hat differentiate populations with respect
to sexual response. In this way, stimuli could well be used in
an empirical study on subjects of ambiguous sexual identity or
sexual orientation (e.g., transgender, bisexual) by interpolation
of their preferences for erotic stimuli from the initial measures
we provide. Since considerable evidence was provided for the
influence of sexual orientation on the perception and processing
of sexual stimuli (e.g.,
Ponseti et al., 2006, 2009), it appears to be
an important direct ion of future research.
The comparison of ratings obt ained from different groups of
subjects revealed that the evaluation of erotic content depended
substantially on sex and sexual orientation of the subjects,
showing that it is necessary to control for these two factors when
choosing experimental material. In line with previous research
on category specificity in sexual arousal patterns (
Chivers et al.,
2004; Safron et al., 2007; Bailey, 2009; Rupp and Wallen, 2009;
Sylva et al., 2013), our results provide evidence for the claim
that both h omosexuals and heterosexuals prefer speci fic erotic
content. Congruent with previous findings (e.g., Ba iley, 2009),
the sexual arous al pattern for heterosexual females appeared to
be less differentiated. Substantial variability of ratings within
the predefined content categories, however, indicates that no
strict categorization can be recognized as appropriate. Since the
strength of the preference for a particular type of sexual stimuli
depends essentially on many characteristics of an image, stimuli
intended to be especially appealing to a given group should
be chosen on the basis of mean ratings (e.g., valence, arousal).
This highlights the need for a more data-driven approach,
rather than the reliance on oversimplified a priori categories of
preferred vs. non-preferred stimuli. The interpretation of the
group differences was previously raised as an important issue.
As the stimuli used in research are not controlled for their
emotional impact, it is unresolved whether the observed group
differences result from different ways of arousal processing or
different level of arousal associated with the stimuli (
Safron et al.,
2007; Rupp and Wallen, 2009). The NAPS ERO provides such an
opportunity, allowing researchers to choose stimuli according to
the mean ratings of valence and arousal, as well as to control for
their technical parameters. Apart from mean ratings, we provide
pairwise comparisons between the mean ratings of different
groups. The statistical tests performed for individual stimuli,
along with t he effect sizes are approximate measures intended
to provide additional guidance in t h e selection process of the
experimental material. Such differential measures may be of
interest to researchers concerned with sex and sexual orientation
differences. The NAPS ERO images, as well as the normative
data are freely available from:, upon the
completion of the registration form. Moreover, the normative
data (ratings and statistical parameters) can be accessed in the
form of an interactive data browser (registration required).
Limitations and Future Directions
As pointed out in the previous sections, sexual stimuli were
referred to with t h e use of variety of subjective measures,
among which perceived sexual arousal was most frequently
mentioned (
Stoléru et al., 2012). Although simultaneous control
for emotional valence and emotional arousal possibly allows
distinguishing sti muli recognized as sexually arousing, it is
important not to confuse these two approaches. Additionally,
apart from the subjective ratings aimed to approximate the
level of sexual arousal experienced by the subjects differing in
terms of sex and sexual orientation, experimental material
provided with NAPS ERO should be further validated
with the use of more objective methods of measurement,
such as photoplethysmography, EDA, eye-tracking
or fMRI.
Another important issue concerns the methods to control
for t h e sexuality of the subjects. Since NAPS ERO ratings have
been collected from individuals manifesting extreme orientation
toward either homosexuality or heterosexuality, furthe r research
should validate the present material on other populations.
Moreover, although most of the previous studies roughly
identified their subjects’ sexuality with self-report methods,
such as Kinsey scale (Kinsey et al., 1948/1998), they certainly
are perceived as imprecise and prone to inaccuracy. Recently,
evidence was provided for the necessity to control for hormone
level in the research on sexual arousal, since the motivation for
and response to erotic content may be strongly influenced by
both the prenatal hormone level, as well as hormonal fluctuations
due to menstrual cycle (e.g.,
Gizewski et al., 2006; Rupp and
Wallen, 2009). Thus, group differences in the NAPS ERO
ratings should be further verified with the control of hormone
We appreciate the help of Paweł Turnau in preparing the web
application for the purpose of ratings collection, as well as in
developing the interactive data browser (
pl). We are also grateful to Maciej Skorko and the VR Lab
( for the possibility of using GEx platform
to collect the questionnaire data. Finally, we would like to
thank Maksymilian Bielecki for his helpful recommendations
regarding statistical analysis. This s tudy was supported by: the
Frontiers in Psychology | 10 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
Polish Ministry of Science and Higher Education, Iuventus Plus
Grant No. IP 2012 042072 (A. Marchewka); the National Science
Centre, PRELUDIUM grant, number 2013/11/N/HS6/0178 6 (M.
Wierzba); and by the BST grant from the University of Warsaw
(W. Dragan).
Supplementary Material
The Supplementary Material for this article can be found
online at:
Arnow, B. A., Desmond, J. E., Banner, L. L., Glover, G. H., Solomon, A., Polan,
M. L., et al. (2002). Brain activation and sexual arousal in healthy, heterosexual
males. Brain 125, 1014–1023. doi: 10.109 3/b rain/awf108
Bailey, J. M. (2009). “What is sexual orientation and do women have one?, in
Contemporary Perspectives on Lesbian, Gay, and Bisexual Identities. Nebraska
Symposium on Motivation, ed D. A. Hope (New York, NY: Springer), 43–63.
doi: 10.1007/978-0-387 - 09 55 6 -1 _3
Berglund, H., Lindström, P., Dhejne-Helmy, C., and Savic, I. (2008). Male-to-
female transsexuals show sex-atypical hypothalamus activation when smelling
odorous steroids. Cereb. Cortex 18, 1900–1908. doi: 10.1093/cercor/bhm216
Berglund, H., Lindström, P., and Savic, I. (2006). Brain response to put ative
pheromones in lesbian women. Proc. Natl. Acad. Sci. U.S.A. 10 3, 8269–8274.
doi: 10.1073/pnas.0600331103
Bradley, M. M., and Lang, P. J. (1994). Measuring emotion: the self-assessment
manikin and the semantic differential. J. Behav. Ther. Exp. Psychiatry 25, 49–59.
doi: 10.1016/0005-791 6(94 )90 0 63 -9
Chivers, M. L., Rieger, G., Latty, E., and Bailey, J. M. (2004). A sex difference in
the specificity of sexual arousal. Psychol. Sci. 15, 736–744. doi: 10.1111/j.0956-
Costumero, V., Barrós-Loscertales, A., Bustamante, J. C., Ventura-Campos, N.,
Fuentes, P., Rosell-Neg re, P., et al. (2013). Reward sensitivity is associated
with brain activity during erotic stimulus processing. PLoS ONE 8:e66940. doi:
Demos, K. E., Heatherton, T. F., and Kelley, W. M. (2012). Individual differences in
nucleus accumbens activity to food and sexual images predict weight gain and
sexual behavior. J. Neurosci. 32, 5549–5552. doi: 10.1523/JNEUROSCI.5958-
Ethofer, T., Wiethoff, S., Anders, S., Kreifelts, B., Grodd, W., and Wildgruber,
D. (2007 ). The voices of seduction: cross-gender effects in processing of
erotic prosody. Soc. Cogn. Affect. Neurosci. 2, 334–337. doi: 10.1093/scan/
Freund, K. (1963). A laboratory method for diagnosing predominance of homo-
or hetero-erotic interest in male. Behav. Res. Ther. 1, 85–93. doi: 10.1016/0005-
Georgiadis, J. R., Farrell, M. J., Boessen, R., Denton, D. A., Gavrilescu, M.,
Kortekaas, R., et al. (2010). Dynamic subcortical blood flow during male
sexual activity with ecological validity: a perfusion fMRI study. Neuroimage 50,
208–216. doi: 10.1016/j.neuroimage.2009.12.034
Georgiadis, J. R., and Holstege, G. (20 0 5). Human brain activation during sexual
stimulation of the penis. J. Comp. Neurol. 493, 33–38. doi: 10.100 2/ cne.207 35
Georgiadis, J. R., Kortekaas, R., Kuipers, R., Nieuwenburg, A., Pruim, J., Reinders,
A. A., et al. (2006). Regional cerebral blood flow changes associated with
clitorally induced orgasm in healthy women. Eur. J. Neurosci. 24, 3305 –3 31 6.
doi: 10.1111/j.1460-956 8.2 00 6.0 52 06 .x
Georgiadis, J. R., and Kringelbach, M. L. (2012). The human sexual response cycle:
brain imaging evidence linking sex to other pleasures. Prog. Neurobiol. 98,
49–81. doi: 10.1016/j.pneurobio.2012.05.004
Gizewski, E. R., Krause, E., Karama, S., Baars, A., Senf, W., and Forsting, M.
(2006). There are differences in cerebral activation between females in distinct
menstrual phases during viewing of erotic stimuli: a fMRI study. Exp. Brain Res.
174, 101–108. doi: 10.1007/s00221-006-0429-3
Hamann, S., Herman, R. A., Nolan, C. L., and Wallen, K. (2004). Men and women
differ in amygdala response to visual sexual stimuli. Nat. Neurosci. 7, 411–416.
doi: 10.1038/nn1208
Holstege, G., Georgiadis, J. R., Paans, A. M., Meiners, L. C., van der Graaf, F. H.,
Reinders, A. A., et al. (2003). Brain activation during human male ejaculation.
J. Neurosci. 23, 9185–9193. Available online at:
Howell, D. C. (2013). Statistical Methods for Psychology, 8th Edn. Belmont, CA:
Wadsworth, Cengage Learning.
Hu, S. H., Wang, Q. D., Xu, Y., Liao, Z. L., Xu, L. J., Liao, Z. L., et al.
(2011). Haemodynamic brain response to visual sexual stimuli is different
between homosexual and heterosexual men. J. Int. Med. Res. 3 9 , 199–211. doi:
Hu, S. H., Wei, N., Wang, Q. D., Yan, L. Q., Wei, E. Q., Zhang, M. M., et al.
(2008). Patterns of brain activation during visually evoked sexual arousal differ
between homosexual and heterosexual men. Am. J. Neuroradiol. 29, 1890–1896.
doi: 10.3174/ajnr.A1260
Jacob, G. A., Arnt z , A., Domes, G., Reiss, N., and Siep, N. (2011). Positive erotic
picture stimuli for emotion research in heterosexual females. Psychiatry Res.
190, 348–351. doi: 10.1016/j.psychres.2011.05.044
Karama, S., Lecours, A. R., Leroux, J. M., Bourgouin, P., Beaudoin, G., Joubert, S.,
et al. (2002). Areas of brain activation in males and females during viewing of
erotic film excerpts. Hum. Brain Mapp. 16, 1–13. doi: 10.1002/hbm.10014
Kinsey, A. C., Pomeroy, W. R., and Martin, C. E. (1948/1998). Sexual Behavior
in the Human Male. Philadelphia; Bloomington: W.B. Saunders; Indiana
University Press.
Knebel, J. F., Toepel, U., Hudry, J., le Coutre, J., and Murray, M. M. (2008).
Generating controlled image sets in cognitive neuroscience research. Brain
Topogr. 20, 284–289. doi: 10.1007/s10548-008-0046-5
Kranz, F., and Ishai, A. (2006). Face perception is modulated by sexual preference.
Curr. Biol. 16, 63–68. doi: 10.1016/j.cub.2005.10.070
Kühn, S., and Gallinat, J. (2014). Brain structure and functional connectivity
associated with pornography consumption: the brain on porn. JAMA Psychiatry
71, 827–834. doi: 10.1001/jamapsychiatry.2014.93
Lang, P. J., Bradley, M. M., and Cuthbert, B. N. (2008). International Affective
Picture System (iaps): Affective Ratings of Pictures and Instruction Manual.
Technical Report A-8, University of Florida, Gainesville, FL.
LeVay, S. (1993). The Sexual Brain. Cambridge: MIT Press
Lewontin, R. C. (2000). “Sex, lies and social sciences, in It Ain’t Necessarily So:
The Dream of the Human Genome and Other Illusions, ed R. C. Lewontin (New
York, NY: New York Review of Books), 237–279.
Loftus, G. R., and Loftus, E. F. (1988). Essence of Statistics, 2nd Edn. New York, NY:
Alfred A. Knopf Series in Psychology.
Marchewka, A.,
Zurawski, Ł., Jednoróg, K., and Grabowska, A. (2014). The Nencki
Affective Picture System (NAPS): introduction to a novel, standardized, wide-
range, high-quality, realistic picture database. Behav. Res. Methods 46, 596–610.
doi: 10.3758/s13428-01 3 -0 37 9- 1
Moulier, V., Mouras, H., Pélégrini-Issac, M ., Glutron, D., Rouxel, R., Grandjean,
B., et al. (2006). Neuroanatomical correlates of penile erection evoked
by photographic stimuli in human males. Neuroimage 33, 689–699. doi:
Mouras, H., Stoléru, S., Moulier, V., Pélégrini-Issac, M., Rouxel, R., Grandjean, B.,
et al. (2008). Activation of mirror-neuron system by erotic video clips predicts
degree of induced erection: an fMRI study. Neuroimage 42, 1142–1150. doi:
Paul, T., Schiffer, B., Zwarg, T., Krüger, T. H., Karama, S., Schedlowski, M., et al.
(2008). Brain response to visual sexual stimuli in heterosexual and homosexual
males. Hum. Brain Mapp. 29, 726–735. doi: 10.1002/hbm.20435
Ponseti, J., Bosinski, H. A., Wolff, S., Peller, M., Jansen, O., Mehdorn, H. M.,
et al. (2006). A functional endophenotype for sexual orientation in humans.
Neuroimage 33, 825–833. doi: 10.1016/j.neuroimage.2006.08.002
Ponseti, J., Granert, O., Jansen, O., Wolff, S., Mehdorn, H., Bosinski, H.,
et al. (2009). Assessment of sexual orientation using the hemodynamic brain
Frontiers in Psychology | 11 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
response to visual sexual stimuli. J. Sex. Med. 6, 1628–1634. doi: 10.1111/j.1743-
Rieger, G., Cash, B. M., Merrill, S. M., Jones-Rounds, J., Dharmavaram, S. M., and
Savin-Williams, R. C. (2015). Sexual arousal: the correspondence of eyes and
genitals. Biol. Psychol. 104, 56–64. doi: 10.1016/ j.biopsycho.2014.11.009
Rupp, H. A., and Wallen, K. (2008). Sex differences in response to visual sexual
stimuli: a review. Arch. Sex. Behav. 37, 206–218. doi: 10.1007/s10508-007-
Rupp, H. A., and Wallen, K. (2009). Sex-specific content preferences for visual
sexual stimuli. Arch. Sex. Behav. 38, 417–426. doi: 10 .10 07 /s1 0 50 8- 0 08 -9 4 02 -5
Safron, A., Barch, B., Bailey, J. M., Gitelman, D. R., Parrish, T. B., and Reber, P.
J. (2007). Neural correlates of sexual arousal in homosexual and heterosexual
men. Behav. Neurosci. 121, 237–248. doi: 10.1037/0735-7044.121.2.237
Savic, I., Berglund, H., and Lindström, P. (2005). Brain response to put ative
pheromones in homosexual men. Proc. Natl. Acad. Sci. U.S.A. 102, 7356–7361.
doi: 10.1073/pnas.0407998102
Savic, I., and Lindström, P. (2008). PET and MRI show differences in
cerebral asymmetry and functional connectivity between homo- and
heterosexual subjects. Proc. Natl. Acad. Sci. U.S.A. 105, 9403–9408. doi:
Sell, R. L. (2007). “Defining and measuring sexual orientation for research,
in The Health of Sexual Minorities, eds I. H. Meyer and M. E. Northridge
(New York, NY: Springer), 355–374. doi: 10.1007/978-0-387-31334-4_14
Sescousse, G., Barbalat, G., Domenech, P., and Dreher, J.-C. (2013). Imbalance in
the sensitivity to different types of rewards in pathological gambling. Brain 136,
2527–2538. doi: 10.1093/brain/awt126
Sescousse, G., Redouté, J., and Dreher, J.-C. (2010). The architecture of reward
value coding in the human orbitofrontal cortex. J. Neurosci. 30, 13095–13104.
doi: 10.1523/JNEUROSCI.3501-10 .20 10
Stevenson, R. A., Stevenson, L. D., Rupp, H. A., Kim, S., Janssen, E., and James, T.
W. (2011). Incorporating emotions specific to the sexual response into theories
of emotion using the Indiana sexual and affective word set. Arch. Sex. Behav.
40, 59–78. doi: 10.1007/s10508-010-9669-1
Stoléru, S., Fonteille, V., Cornélis, C., Joyal, C., and Moulier, V. (2012). Functional
neuroimaging studies of sexual arousal and orgasm in healthy men and women:
a review and meta-analysis. Neurosci. Biobehav. Rev. 36, 1481–1509. doi:
Sylva, D., Safron, A., Rosenthal, A. M., Reber, P. J., Parrish, T. B., and Bailey, J.
M. (2013). Neural correlates of sexual arousal in heterosexual and homosexual
women and men. Horm. Behav. 64, 673–684. doi: 10.1016/j.yhbeh.2013.08.003
Voon, V., Mole, T. B., Banca, P., Porter, L., Morris, L., Mitchell, S., et al.
(2014). Neu ral correlates of sexual cue reactivity in individuals with
and without compulsive sexual behaviours. PLoS ONE 9:e102419. doi:
Walter, M., Stadler, J., Tempelmann, C., Speck, O., and Northoff, G. (2008). High
resolution fMRI of sub cortic al regions during visual erotic stimulation at 7 T.
Magn. Reson. Mater Phys. 21, 103–111. doi: 10.1007/s10334-007-0103-1
Willenbockel, V., Sadr, J., Fiset, D., Horne, G. O., Gosselin, F., and Tanaka, J. W.
(2010). Controlling low-level image properties: the SHINE toolbox. Behav. Res.
Methods 42, 671–684. doi: 10.3758/BRM.4 2.3 .671
Zhang, M., Hu, S., Xu, L., Wang, Q., Xu, X., Wei, E., et al. (2011). Neural
circuits of disg ust induced by sexual stimuli in homosexual and heterosexual
men: an fMRI study. Eur. J. Radiol. 80, 418–42 5. doi: 10.1016/j.ejrad.2010.
Conflict of Interest Statement: The authors declare that the research was
conducted in the absence of any commercial or financial relationships that could
be construed as a potential conflict of interest.
Copyright © 2015 Wierzba, Riegel, Pucz, Le
sniewska, Dragan, Gola, Jednoróg and
Marchewka. This is an open-access article distributed under the terms of the Creative
Commons Attribution License (CC BY). The use, di stri bution or reproduction in
other forums is permitted, provided the original author(s) or licensor are credited
and that the original publication in this journal is cited, in accordance with accepted
academic practice. No use, distribution or reproduction is permitted which does not
comply with these terms.
Frontiers in Psychology | 12 September 2015 | Volume 6 | Article 1336
Wierzba et al. NAPS ERO: erotic pictures database
Description of the database
ID Name identifying each of the images; the name contains
the information on the content c at e gory name, the ordinal
number and the subscript referring to the image orientation
(h horizontal, v vertical)
Category Name of the erotic content category, i.e. Opposite-
sex Couple, Male Couple, Female Couple, Male, Female
Nr Ordinal number of the image, as counted separately for
each of the content category
V/H Denotes image orientation: h horizont al, v - vertical
val_M_HoF - Mean (M) of valence ratings in the homosexual
female group, ranging from 1 to 9, where: 1 very negative
emotions, to 9 - very positive emotions
val_SD_HoF - Standard de via tion (SD) of valence ratings in the
homosexual female group
val_M_HoM - Mean (M) of valence ratings in the homosexual
male group, ranging from 1 to 9, where: 1 very negative
emotions, to 9 - very positive emotions
val_SD_HoM - Standard deviation (SD) of valence ratings in the
homosexual male group
val_M_HeF - Mean (M) of valence ratings in the heterosexual
female group, ranging from 1 to 9, where: 1 very negative
emotions, to 9 - very positive emotions
val_SD_HeF - Standard devia tion (SD) of valence ratings in the
heterosexual female group
val_M_HeM - Mean (M) of valence ratings in t h e heterosexual
male group, ranging from 1 to 9, where: 1 very negative
emotions, to 9 - very positive emotions
val_SD_HeM - Sta nd ard deviation (SD) of valence ratings in the
heterosexual male group
aro_M_HoF - Mean (M) of arousal ratings in the homosexual
female group, ranging from 1 to 9, where: 1 weak emotions,
being emotionally unaroused, to 9 - strong emotions, being
emotionally aroused
aro_SD_HoF - Stand a rd deviation (SD) of arousal ratings in the
homosexual female group
aro_M_HoM - Mean (M) of arousal ratings in the homosexual
male group, ranging from 1 to 9, where: 1 weak emotions, being
emotionally unaroused, to 9 - strong emotions, being emotionally
aro_SD_HoM - Standard deviation (SD) of arousal ratings in
the h omosexual male group
aro_M_HeF - Mean (M) of arousal ratings in the heterosexual
female group, ranging from 1 to 9, where: 1 weak emotions,
being emotionally unaroused, to 9 - strong emotions, being
emotionally aroused
aro_SD_HeF - Standard deviation (SD) of arousal ratings in the
heterosexual female group
aro_M_HeM - Mean (M) of arousal ratings in the heterosexual
male group, ranging from 1 to 9, where: 1 weak emotions,
being emotionally unaroused, to 9 - strong emotions, being
emotionally aroused
aro_SD_HeM - Standard deviation (SD) of arousal ratings in the
heterosexual male group
Width Image width in pixels
Height Image height in pixels
Luminance - Average pixel values of grayscaled image (PI L
library, ver. 1.1.7)
Contrast - Standard deviation of pixel values of grayscaled image
(PIL library, ver. 1.1.7)
JPEG_size80 JPEG size as an index of overall complexity of
an image. JPEG size was determined for color image with a
compression quality setting of 80 on a scale from 1 to 100 (PIL
library, ver. 1.1.7). The bigger the JPEG size, the more complex
an image
LABL Average luminance (L
) in the CIE L
color space
= 0 for black and L
= 100 for white pixels) (PIL library,
ver. 1.1.7)
LABA - Average a
value in the CIE L
color space
= 100 for green and a
= 100 for red pixels) (PIL library,
ver. 1.1.7)
LABB - Average b
value in the CIE L
color space
= 100 for blue and b
= 100 for yellow pixels) (PIL library,
ver. 1.1.7)
Entropy - Entropy (H) of gray scaled image, computed from the
histogram of 8-bit gray-level intensity values x: H = 6p(x)log
p(x), where p represents t he frequency of intensity x (PIL
library, ver. 1.1.7). The higher the entropy, the more random
the image
Frontiers in Psychology | 13 September 2015 | Volume 6 | Article 1336
... The emotional stimuli used in this study were largely based on the emotional stimuli used in Gomez et al.'s [93] study, which examined young and old participants, and were taken from the International Affective Picture System (IAPS) [94] and the Nencki Affective Picture System (NAPS) [95][96][97][98] [94] and NAPS [95]. The 7 positive sets included content such as stimulating desserts, heterosexual couple love, babies, happy children, pleasant nature, pets, and sports scenes. ...
Full-text available
Emotion regulation in old age was found to be more efficient; seniors seem to focus less on the negative aspects of experiences. Here, we ask, do older individuals regulate their emotions more efficiently or are they numb to the physiological changes that modulate these emotions? Interoception, the perception of physical feelings, influences a person’s mood, emotions, and sense of well-being, and was hardly tested among older adults. We examined the awareness of physiological changes (physiological arousal—blood pressure and heart rate) of 47 older adults, compared to 18 young adults, and their subjective reports of emotional experiences while viewing emotional stimuli. Interoception was decreased in old age. Blood pressure medications had a partial role in this reduction. Moreover, interoception mediated emotional experience, such that low interoception led to lower experiences of changes in physiological arousal. These findings may account for the emotional changes in old age, suggesting a decline in sensitivity with age, which leads to a positive interpretation of information.
... As previously recommended and reported (Ruiz-Padial et al., 2021;Wierzba et al., 2015), the internal consistency of participant assessments was estimated by calculating split-half reliability scores. To this end, participants were numbered according to their order of participation. ...
Full-text available
A large number of publications have focused on the study of pain expressions. Despite the growing knowledge, the availability of pain-related face databases is still very scarce compared with other emotional facial expressions. The Pain E-Motion Faces Database (PEMF) is a new open-access database currently consisting of 272 micro-clips of 68 different identities. Each model displays one neutral expression and three pain-related facial expressions: posed, spontaneous-algometer and spontaneous-CO2 laser. Normative ratings of pain intensity, valence and arousal were provided by students of three different European universities. Six independent coders carried out a coding process on the facial stimuli based on the Facial Action Coding System (FACS), in which ratings of intensity of pain, valence and arousal were computed for each type of facial expression. Gender and age effects of models across each type of micro-clip were also analysed. Additionally, participants' ability to discriminate the veracity of pain-related facial expressions (i.e., spontaneous vs posed) was explored. Finally, a series of ANOVAs were carried out to test the presence of other basic emotions and common facial action unit (AU) patterns. The main results revealed that posed facial expressions received higher ratings of pain intensity, more negative valence and higher arousal compared with spontaneous pain-related and neutral faces. No differential effects of model gender were found. Participants were unable to accurately discriminate whether a given pain-related face represented spontaneous or posed pain. PEMF thus constitutes a large open-source and reliable set of dynamic pain expressions useful for designing experimental studies focused on pain processes.
... The dimensional picture ratings of NAPS were collected using Likert-scale questionnaires, while participants in the creation of NAPS BE provided their subjective ratings In later efforts to expand NAPS, an erotic subgroup was introduced for the Nencki Affective Picture System (NAPS ERO) with an additional 200 stimulus pictures that were provided with self-reported ratings of emotional valence and arousal by homosexual and heterosexual men and women (N = 80, divided into four equally sized subgroups) [43]. Finally, Children-Rated Subset is the most recent extension of NAPS and includes 1128 images from the original database that were rated as appropriate for children based on various criteria and expert judgment. ...
Full-text available
Digital documents created to evoke emotional responses are intentionally stored in special affective multimedia databases, along with metadata describing their semantics and emotional content. These databases are routinely used in multidisciplinary research on emotion, attention, and related phenomena. Affective dimensions and emotion norms are the most common emotion data models in the field of affective computing, but they are considered separable and not interchangeable. The goal of this study was to determine whether it is possible to statistically infer values of emotionally annotated pictures using the discrete emotion model when the values of the dimensional model are available and vice versa. A positive answer would greatly facilitate stimuli retrieval from affective multimedia databases and the integration of heterogeneous and differently structured affective data sources. In the experiment, we built a statistical model to describe dependencies between discrete and dimensional ratings using the affective picture databases NAPS and NAPS BE with standardized annotations for 1356 and 510 pictures, respectively. Our results show the following: (1) there is a statistically significant correlation between certain pairs of discrete and dimensional emotions in picture stimuli, and (2) robust transformation of picture ratings from the discrete emotion space to well-defined clusters in the dimensional space is possible for some discrete-dimensional emotion pairs. Based on our findings, we conclude that a feasible recommender system for affective dataset retrieval can be developed. The software tool developed for the experiment and the results are freely available for scientific and non-commercial purposes.
... SD = 14.04). 90.3% of the sample declared being exclusively or predominantly heterosexual, while 6.4% reported being predominantly or exclusively homosexual (as assessed by the Polish version of the Kinsey Sexual Orientation Scale, Wierzba et al., 2015). 78.9% of participants declared being Catholic, 9.6%-atheist or agnostic, 3.6% declared being of other religious alignment, and 7.9% chose the "none of the above" response option. ...
Full-text available
Previous studies have shown that specific attitudes related to moral convictions can have an important role in the development and maintenance of problematic sexual behavior symptoms. However, although other types of attitudes, like sexual attitudes, are potentially highly relevant, they have not yet been studied in this role. We investigated how four dimensions of sexual attitudes: Permissiveness, Birth Control, Communion and Instrumentality, contribute to problematic pornography use (PPU) and hypersexual disorder (HD) symptoms, controlling for religiosity, sex, age and relationship status. The study was administered through an online questionnaire and based on a representative sample of n = 1036 (Mage = 43.28, SD = 14.21; 50.3% women) Polish adult citizens. When adjusting for other variables, higher sexual Permissiveness positively predicted HD and PPU among both men (HD: β = .26, p < .001; PPU: β = .22, p < .001) and women (HD: β = .44, p < .001; PPU: β = .26; p < .001). Sexual Instrumentality positively, although weakly, contributed to HD severity among men (β = .11, p < .05). Attitudes reflecting higher support for responsible sexuality (Birth Control subscale) negatively and weakly predicted HD among women (β = – .11, p < .05). Permissiveness was also the only sexual attitude dimension that consistently predicted a higher frequency of sexual activity among men and women. Based on the cutoff criteria proposed by the authors of the used screening instruments (≥ 53 points for the Hypersexual Behavior Inventory and ≥ 4 points for the Brief Pornography Screen), the prevalence of being at risk for HD was 10.0% (men: 11.4%, women: 8.7%) and for PPU was 17.8% (men: 26.8%, women: 9.1%). Our results point to a significant contribution of sexual attitudes to problematic sexual behavior symptoms, which was not encapsulated by the previously studied influence of religious beliefs, although most of the obtained relationships were relatively weak. Particularly, a consistent link between permissive attitudes and both HD and PPU among men and women may indicate that permissive attitudes can potentially contribute to the development and maintenance of problematic sexual behavior. The prevalence of being at risk for PPU (and to some degree HD) in the current representative sample was high. Such results raise questions about the appropriateness of the proposed cutoff criteria and the risk of overpathologizing normative sexual activity, if the cutoff thresholds are not tailored adequately. The results have implications for the assessment, diagnosis and theory of problematic sexual behavior.
... Sexual orientation was assessed via a Polish adaptation (Wierzba et al., 2015) of the Sell Assessment of Sexual Orientation (Sell, 1996). This tool measures three dimensions of sexual orientation: sexual attractions, sexual contact, and sexual identity. ...
Full-text available
The link between gender nonconformity and psychopathology may be due in part to negative childhood experiences resulting from other people's reactions to gender nonconformity. The aim of this study was to test whether recalled perceived levels of parental and peer acceptance of childhood gender nonconforming behaviors and play mediate the relationship of childhood gender nonconformity with depression and social anxiety in adulthood. We also tested whether this relationship was moderated by sexual orientation and, among gay men, whether internalized homophobia was an additional mediator. All variables were measured in a large sample of male participants using self-report (n = 449 gay men, age: M = 27.8 years, SD = 6.69; and n = 296 heterosexual men, age: M = 27.4 years, SD = 6.57) in Poland. Gay men reported more childhood gender nonconformity than heterosexual men. The relationship between gender nonconformity and depressive symptoms as well as social anxiety symptoms was significant in both gay and heterosexual men. Among gay men, this relationship was partially mediated by peer but not parental acceptance of the measured aspects of gender nonconformity and internalized homophobia. Among heterosexual men, recalled perceived parental acceptance of gender nonconformity partially mediated the relationship between gender nonconformity and depressive and social anxiety symptoms. Our findings were partially in line with those found in Western European and North American samples. Although the two groups differed in their recalled perceived gender nonconformity, they did not differ in their depression or social anxiety scores. Nevertheless, childhood gender nonconformity may be an indirect risk associated with mental health symptoms, irrespective of sexual orientation. Its higher prevalence among nonheterosexual individuals makes it a particular risk for this group.
The International Affective Picture System (IAPS) is used globally in emotion research. However, normative studies in diverse contexts do not consider the influence of education and socioeconomic status (SES) on picture ratings. We created the South African Affective Picture System (SA-APS) for use in low- and middle-income countries (LMICs) by replacing some original IAPS images with pictures featuring more diverse groups of people and culturally appropriate stimuli. Healthy South African adults from higher and lower education/SES backgrounds (n = 80; n = 70 respectively) provided valence and arousal ratings for 340 images from the original IAPS and 340 images from the new SA-APS. Overall, their ratings of SA-APS images were better aligned with the US normative standards than their ratings of IAPS images, particularly with regard to valence. Those with higher SES/education rated IAPS images differently from those with lower SES/education (e.g., valence ratings of the latter were similar to US normative standards, whereas those of the former were more negative). Regression modelling indicated that sex and SES significantly predicted the current sample’s IAPS and SA-APS ratings (e.g., women and higher-SES participants rated high-arousal images as being significantly more arousing than men and lower-SES participants); hence, we created regression-based norms for both picture sets. These norms are especially useful in emotion research, because few studies emerge from LMICs, and few instruments account for substantial sociodemographic diversity. Extending the reach of tools such as the IAPS to LMICs can help ensure a more globally representative body of research in this field.
Recent work has cast doubt on whether the strength of motivation (strength of avoidance or approach tendencies) experienced while viewing emotion-eliciting pictures is dissociable from felt valence (negative versus positive). The present study extended this work by testing specific discrete emotions (amusement, anger, awe, desire, sadness). Previous work has proposed separate motivational direction (avoid versus approach) from valence. In Study 1, participants (N = 60) rated the motivational direction or valence they experienced while viewing 100 pictures that each evoked one of the five discrete emotions. We found significant differences between average motivational direction and valence ratings for sadness, anger, and amusement. Critically, underlying these averages, we found that while valence responses were highly consistent, there was large variability in motivational direction, with some people indicating they wanted to approach and others indicating they wanted to avoid while viewing the same picture. Individual differences in motivational direction were largest for sadness, so in Study 2 (N = 100) we tested whether they were predicted by appraisals of the situation (e.g., ratings of how welcome or useful people believed their help would be). The three appraisals tested accounted for 64% of the variance in motivational direction, after which valence made a very small unique contribution. These findings highlight that motivational direction and valence can diverge. Given the variability in individuals' motivational direction responses, future studies designed to assess the effects of motivational direction on cognitive processes need to tailor stimuli for each participant to ensure they activate the intended motivational direction. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
Gender Role Conflict (GRC) yields intensive psychological discomfort due to restrictive gender roles. However, there is no visual stimuli database portraying GRC contexts/domains. The goal of this pilot study is to assemble stimuli (a) reflecting GRC contexts and (b) rate them on emotional dimensions (valence, arousal, uneasiness), for norming purposes. Initially, 53 photos were included from the Nencki Affective Picture System and the internet. Based on the four GRC domain definitions, we divided the photos into four categories. Straight and gay men (n = 22) rated each photo on (i) the extent to which it depicted a GRC domain, (ii) the three emotional dimensions. Photos rated above scale midpoint as depicting a GRC domain were classified accordingly and comprised the "Gender Role Affective Stimuli Pool" (GRASP) with 31 photos. Straight participants rated Restricted Emotionality (RE) and Restrictive Affectionate Behavior Between Men (RABBM) photos as less pleasant (low valence) than gay men. High GRC participants rated RE photos as more pleasant and arousing and RABBM ones as more uneasiness-inducing than low GRC participants. Men seem to differentiate their affective reaction to photos illustrating GRC domains; hence, GRASP may be useful to future experimental research examining cognitive and affective consequences of men's adherence to gender roles.
Background Compulsive Sexual Behavior Disorder (CSBD) was recently included in ICD-11 as a new impulse control disorder. While this certainly improved the diagnosis of CSBD, the underlying brain mechanisms of the disorder are still poorly understood. Better description of brain functional deficits is required. Aim Here we investigate patterns of resting-state brain functional connectivity (fc) in a group of CSBD patients compared to a group of healthy controls (HC). Methods A MATLAB toolbox named CONN functional connectivity toolbox was employed to study patterns of brain connectivity. Also correlation between fc and severity of CSBD symptoms and other psychological characteristics, assessed with questionnaires, were examined. Outcomes We collected resting-state functional magnetic resonance imaging data from 81 heterosexual males: 52 CSBD patients and 29 HC. Results We found increased fc between left inferior frontal gyrus and right planum temporale and polare, right and left insula, right Supplementary Motor Cortex (SMA), right parietal operculum, and also between left supramarginal gyrus and right planum polare, and between left orbitofrontal cortex and left insula when compared CSBD and HC. The decreased fc was observed between left middle temporal gyrus and bilateral insula and right parietal operculum. No significant correlations between psychological questionnaires assessing CSBD symptoms and resting-state functional connectivity were observed. Clinical Implications Results from our study extend the knowledge of brain mechanisms differentiating CSBD from HC. Strengths & Limitations The study was the first large sample study showing 5 distinct functional brain networks differentiating CSBD patients and HC. However, the sample was limited only to heterosexual men, in the future a greater diversity in studied sample and longitudinal studies are needed. Also, the present study examined functional connectivity at the level of regions of interest (ROIs). Future studies could verify these results by examining functional connectivity at the voxel level. Conclusion The identified functional brain networks differentiate CSBD from HC and provide some support for incentive sensitization as mechanism underlying CSBD symptoms. The correlation between psychological assessment (ie, severity of CSBD, depression and anxiety symptoms, level of impulsivity and compulsivity) and resting-state functional connectivity need further examination. Draps M, Adamus S, Wierzba M, et al. Functional Connectivity in Compulsive Sexual Behavior Disorder - Systematic Review of Literature and Study on Heterosexual Males. J Sex Med 2022;XX:XXX–XXX.
Full-text available
Although compulsive sexual behaviour (CSB) has been conceptualized as a "behavioural" addiction and common or overlapping neural circuits may govern the processing of natural and drug rewards, little is known regarding the responses to sexually explicit materials in individuals with and without CSB. Here, the processing of cues of varying sexual content was assessed in individuals with and without CSB, focusing on neural regions identified in prior studies of drug-cue reactivity. 19 CSB subjects and 19 healthy volunteers were assessed using functional MRI comparing sexually explicit videos with non-sexual exciting videos. Ratings of sexual desire and liking were obtained. Relative to healthy volunteers, CSB subjects had greater desire but similar liking scores in response to the sexually explicit videos. Exposure to sexually explicit cues in CSB compared to non-CSB subjects was associated with activation of the dorsal anterior cingulate, ventral striatum and amygdala. Functional connectivity of the dorsal anterior cingulate-ventral striatum-amygdala network was associated with subjective sexual desire (but not liking) to a greater degree in CSB relative to non-CSB subjects. The dissociation between desire or wanting and liking is consistent with theories of incentive motivation underlying CSB as in drug addictions. Neural differences in the processing of sexual-cue reactivity were identified in CSB subjects in regions previously implicated in drug-cue reactivity studies. The greater engagement of corticostriatal limbic circuitry in CSB following exposure to sexual cues suggests neural mechanisms underlying CSB and potential biological targets for interventions.
Full-text available
Selecting appropriate stimuli to induce emotional states is essential in affective research. Only a few standardized affective stimulus databases have been created for auditory, language, and visual materials. Numerous studies have extensively employed these databases using both behavioral and neuroimaging methods. However, some limitations of the existing databases have recently been reported, including limited numbers of stimuli in specific categories or poor picture quality of the visual stimuli. In the present article, we introduce the Nencki Affective Picture System (NAPS), which consists of 1,356 realistic, high-quality photographs that are divided into five categories (people, faces, animals, objects, and landscapes). Affective ratings were collected from 204 mostly European participants. The pictures were rated according to the valence, arousal, and approach–avoidance dimensions using computerized bipolar semantic slider scales. Normative ratings for the categories are presented for each dimension. Validation of the ratings was obtained by comparing them to ratings generated using the Self-Assessment Manikin and the International Affective Picture System. In addition, the physical properties of the photographs are reported, including luminance, contrast, and entropy. The new database, with accompanying ratings and image parameters, allows researchers to select a variety of visual stimulus materials specific to their experimental questions of interest. The NAPS system is freely accessible to the scientific community for noncommercial use by request at Electronic supplementary material The online version of this article (doi:10.3758/s13428-013-0379-1) contains supplementary material, which is available to authorized users.
Full-text available
The behavioral approach system (BAS) from Gray's reinforcement sensitivity theory is a neurobehavioral system involved in the processing of rewarding stimuli that has been related to dopaminergic brain areas. Gray's theory hypothesizes that the functioning of reward brain areas is modulated by BAS-related traits. To test this hypothesis, we performed an fMRI study where participants viewed erotic and neutral pictures, and cues that predicted their appearance. Forty-five heterosexual men completed the Sensitivity to Reward scale (from the Sensitivity to Punishment and Sensitivity to Reward Questionnaire) to measure BAS-related traits. Results showed that Sensitivity to Reward scores correlated positively with brain activity during reactivity to erotic pictures in the left orbitofrontal cortex, left insula, and right ventral striatum. These results demonstrated a relationship between the BAS and reward sensitivity during the processing of erotic stimuli, filling the gap of previous reports that identified the dopaminergic system as a neural substrate for the BAS during the processing of other rewarding stimuli such as money and food.
Importance Since pornography appeared on the Internet, the accessibility, affordability, and anonymity of consuming visual sexual stimuli have increased and attracted millions of users. Based on the assumption that pornography consumption bears resemblance with reward-seeking behavior, novelty-seeking behavior, and addictive behavior, we hypothesized alterations of the frontostriatal network in frequent users.Objective To determine whether frequent pornography consumption is associated with the frontostriatal network.Design, Setting, and Participants In a study conducted at the Max Planck Institute for Human Development in Berlin, Germany, 64 healthy male adults covering a wide range of pornography consumption reported hours of pornography consumption per week. Pornography consumption was associated with neural structure, task-related activation, and functional resting-state connectivity.Main Outcomes and Measures Gray matter volume of the brain was measured by voxel-based morphometry and resting state functional connectivity was measured on 3-T magnetic resonance imaging scans.Results We found a significant negative association between reported pornography hours per week and gray matter volume in the right caudate (P < .001, corrected for multiple comparisons) as well as with functional activity during a sexual cue–reactivity paradigm in the left putamen (P < .001). Functional connectivity of the right caudate to the left dorsolateral prefrontal cortex was negatively associated with hours of pornography consumption.Conclusions and Relevance The negative association of self-reported pornography consumption with the right striatum (caudate) volume, left striatum (putamen) activation during cue reactivity, and lower functional connectivity of the right caudate to the left dorsolateral prefrontal cortex could reflect change in neural plasticity as a consequence of an intense stimulation of the reward system, together with a lower top-down modulation of prefrontal cortical areas. Alternatively, it could be a precondition that makes pornography consumption more rewarding.
INTRODUCTION: The assessment of sexual orientation is of importance to the diagnosis and treatment of sex offenders and paraphilic disorders. Phallometry is considered gold standard in objectifying sexual orientation, yet this measurement has been criticized because of its intrusiveness and limited reliability. AIM: To evaluate whether the spatial response pattern to sexual stimuli as revealed by a change in blood oxygen level-dependent (BOLD) signal can be used for individual classification of sexual orientation. METHODS: We used a preexisting functional MRI (fMRI) data set that had been acquired in a nonclinical sample of 12 heterosexual men and 14 homosexual men. During fMRI, participants were briefly exposed to pictures of same-sex and opposite-sex genitals. Data analysis involved four steps: (i) differences in the BOLD response to female and male sexual stimuli were calculated for each subject; (ii) these contrast images were entered into a group analysis to calculate whole-brain difference maps between homosexual and heterosexual participants; (iii) a single expression value was computed for each subject expressing its correspondence to the group result; and (iv) based on these expression values, Fisher's linear discriminant analysis and the kappa-nearest neighbor classification method were used to predict the sexual orientation of each subject. MEAN OUTCOME MEASURE: Sensitivity and specificity of the two classification methods in predicting individual sexual orientation. RESULTS: Both classification methods performed well in predicting individual sexual orientation with a mean accuracy of >85% (Fisher's linear discriminant analysis: 92% sensitivity, 85% specificity; kappa-nearest neighbor classification: 88% sensitivity, 92% specificity). CONCLUSION: Despite the small sample size, the functional response patterns of the brain to sexual stimuli contained sufficient information to predict individual sexual orientation with high accuracy. These results suggest that fMRI-based classification methods hold promise for the diagnosis of paraphilic disorders (e.g., pedophilia).
Most men have a category-specific pattern of genital and subjective sexual arousal, responding much more strongly to erotic stimuli depicting their preferred sex than to erotic stimuli depicting their nonpreferred sex. In contrast, women tend to have a less specific arousal pattern. To better understand this sex difference, we used neuroimaging to explore its neural correlates. Heterosexual and homosexual women viewed erotic photographs of either men or women. Evoked neural activity was monitored via fMRI and compared with responses to the same stimuli in heterosexual and homosexual men. Overall, a network of limbic (as well as the anterior cingulate) and visual processing regions showed significantly less category-specific activity in women than men. This was primarily driven by weaker overall activations to preferred-sex stimuli in women, though there was also some evidence of stronger limbic activations to nonpreferred-sex stimuli in women. Primary results were similar for heterosexual and homosexual participants. Women did show some evidence of category-specific responses in the visual processing regions, although even in these regions they exhibited less differential activity than men. In the anterior cingulate, a region with high concentrations of sex-hormone receptors, subjective and neural category specificity measures correlated positively for women but negatively for men, suggesting a possible sex difference in the role of the anterior cingulate. Overall, results suggest that men tend to show more differentiated neural responses than do women to erotic photographs of one sex compared to the other sex, though women may not be entirely indifferent to which sex is depicted.