Nencki Affective Picture System Research Articles

The Impact of Light Conditions on Neural Affect Classification: A Deep Learning Approach

Understanding and detecting human emotions is crucial for enhancing mental health, cognitive performance and human–computer interactions. This field in affective computing is relatively unexplored, and gaining knowledge about which external factors impact emotions could enhance communication between users and machines. Furthermore, it could also help us to manage affective disorders or understand affective physiological responses to human spatial and digital environments. The main objective of the current study was to investigate the influence of external stimulation, specifically the influence of different light conditions, on brain activity while observing affect-eliciting pictures and their classification. In this context, a multichannel electroencephalography (EEG) was recorded in 30 participants as they observed images from the Nencki Affective Picture System (NAPS) database in an art-gallery-style Virtual Reality (VR) environment. The elicited affect states were classified into three affect classes within the two-dimensional valence–arousal plane. Valence (positive/negative) and arousal (high/low) values were reported by participants on continuous scales. The experiment was conducted in two experimental conditions: a warm light condition and a cold light condition. Thus, three classification tasks arose with regard to the recorded brain data: classification of an affect state within a warm-light condition, classification of an affect state within a cold light condition, and warm light vs. cold light classification during observation of affect-eliciting images. For all classification tasks, Linear Discriminant Analysis, a Spatial Filter Model, a Convolutional Neural Network, the EEGNet, and the SincNet were compared. The EEGNet architecture performed best in all tasks. It could significantly classify three affect states with 43.12% accuracy under the influence of warm light. Under the influence of cold light, no model could achieve significant results. The classification between visual stimulus with warm light vs. cold light could be classified significantly with 76.65% accuracy from the EEGNet, well above any other machine learning or deep learning model. No significant differences could be detected between affect recognition in different light conditions, but the results point towards the advantage of gradient-based learning methods for data-driven experimental designs for the problem of affect decoding from EEG, providing modern tools for affective computing in digital spaces. Moreover, the ability to discern externally driven affective states through deep learning not only advances our understanding of the human mind but also opens avenues for developing innovative therapeutic interventions and improving human–computer interaction.

Knowledge Graph Dataset for Semantic Enrichment of Picture Description in NAPS Database

This data description introduces a comprehensive knowledge graph (KG) dataset with detailed information about the relevant high-level semantics of visual stimuli used to induce emotional states stored in the Nencki Affective Picture System (NAPS) repository. The dataset contains 6808 systematically manually assigned annotations for 1356 NAPS pictures in 5 categories, linked to WordNet synsets and Suggested Upper Merged Ontology (SUMO) concepts presented in a tabular format. Both knowledge databases provide an extensive and supervised taxonomy glossary suitable for describing picture semantics. The annotation glossary consists of 935 WordNet and 513 SUMO entities. A description of the dataset and the specific processes used to collect, process, review, and publish the dataset as open data are also provided. This dataset is unique in that it captures complex objects, scenes, actions, and the overall context of emotional stimuli with knowledge taxonomies at a high level of quality. It provides a valuable resource for a variety of projects investigating emotion, attention, and related phenomena. In addition, researchers can use this dataset to explore the relationship between emotions and high-level semantics or to develop data-retrieval tools to generate personalized stimuli sequences. The dataset is freely available in common formats (Excel and CSV).

A Pilot Study Testing A New Visual Stimuli Database for Probing Men’s Gender Role Conflict: GRASP (Gender Role Affective Stimuli Pool)

ABSTRACTGender 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.

Exploring psychopathy traits on intertemporal decision-making, neurophysiological correlates, and emotions on time estimation in community adults

There are certain characteristics of psychopathy that may be related to changes in intertemporal choices. Specifically, traits such as impulsivity or lack of inhibitory control may be associated with a more pronounced discounting function in intertemporal choices (IC) and, in turn, this function may be based on changes in the basic mechanisms of time estimation (TE). Therefore, this study aimed to examine potential differences in neurophysiological correlates, specifically through N1, P3, and LPP measurements, which may be related to TE and IC, examining their modulation according to psychopathic traits, different emotional conditions, and different decision-making conditions. This experimental study included 67 adult participants (48 women) from the northern region of Portugal, who performed an intertemporal decision-making task and, of those, 19 participants (16 women), with a mean age of 25 years (SD = 5.41) and a mean of 16 years of schooling (SD = 3.37) performed the time estimation task. The instruments/measures applied were MoCA, used as a neurocognitive screening tool; the Triarchic Psychopathy Measure (TriPM), a self-report instrument with 58 items that map the core features of psychopathy along three facets – boldness, meanness, and disinhibition – and considers them continuously distributed among the general population; intertemporal decision-making and time estimation tasks – for the time estimation task, the stimuli consisted of 45 color images extracted from the Nencki Affective Picture System (NAPS). In the TE task, there was an almost significant effect of disinhibition on the values of θ, with higher values on this variable associated with greater values of θ in the unpleasant emotional condition. In the IC task, there were no significant effects of any psychopathy measure on the values of the gains and losses ratios. In addition, the analysis of the neurophysiological correlates of the IC task did not reveal a main effect of the decision-making condition, nor effects of any psychopathy measure on the N1 and P3 amplitudes. The analysis of the neurophysiological correlates of the TE task revealed that higher meanness values are associated with smaller N1 amplitude in the pleasant emotional condition, whereas higher disinhibition values are associated with greater N1 amplitude in the pleasant emotional condition. Still in this task, higher disinhibition values were associated with a smaller LPP amplitude in the unpleasant emotional condition. The increase in the distribution of attention resources towards time and/or the increase in activation states, including those originated by responses to emotional stimuli, may be the main factor that alters the way impulsive individuals and, presumably, individuals with high psychopathy, consider time when making decisions.

Assessing the Robustness of Cluster Solutions in Emotionally-Annotated Pictures Using Monte-Carlo Simulation Stabilized K-Means Algorithm

Clustering is a very popular machine-learning technique that is often used in data exploration of continuous variables. In general, there are two problems commonly encountered in clustering: (1) the selection of the optimal number of clusters, and (2) the undecidability of the affiliation of border data points to neighboring clusters. We address both problems and describe how to solve them in application to affective multimedia databases. In the experiment, we used the unsupervised learning algorithm k-means and the Nencki Affective Picture System (NAPS) dataset, which contains 1356 semantically and emotionally annotated pictures. The optimal number of centroids was estimated, using the empirical elbow and silhouette rules, and validated using the Monte-Carlo simulation approach. Clustering with k = 1–50 centroids is reported, along with dominant picture keywords and descriptive statistical parameters. Affective multimedia databases, such as the NAPS, have been specifically designed for emotion and attention experiments. By estimating the optimal cluster solutions, it was possible to gain deeper insight into affective features of visual stimuli. Finally, a custom software application was developed for study in the Python programming language. The tool uses the scikit-learn library for the implementation of machine-learning algorithms, data exploration and visualization. The tool is freely available for scientific and non-commercial purposes.

A Bottom-Up Validation of the IAPS, GAPED, and NAPS Affective Picture Databases: Differential Effects on Behavioral Performance.

The concept of emotion is a complex neural and psychological phenomenon, central to the organization of human social behavior. As the result of subjective experience, emotions involve bottom-up cognitive styles responsible for efficient adaptation of human behavior to the environment based on salient goals. Indeed, bottom-up cognitive processes are mandatory for clarifying emotion-cognition interactions. Accordingly, a huge number of studies and standardized affective stimuli databases have been developed (i.e., International Affective Picture System (IAPS), Geneva Affective Picture Database (GAPED), and Nencki Affective Picture System (NAPS)). However, these neither accurately reflect the complex neural system underlying emotional responses nor do they offer a comprehensive framework for researchers. The present article aims to provide an additional bottom-up validation of affective stimuli that are independent from cognitive processing and control mechanisms, related to the implicit relevance and evolutionistic significance of stimuli. A subset of 360 images from the original NAPS, GAPED, and IAPS datasets was selected in order to proportionally cover the whole dimensional affective space. Among these, using a two-step analysis strategy, we identified three clusters (“good performance”, “poor performance”, and “false alarm”) of stimuli with similar cognitive response profiles. Results showed that the three clusters differed in terms of arousal and database membership, but not in terms of valence. The new database, with accompanying ratings and image parameters, allows researchers to select visual stimuli independent from dimensional/discrete-categories, and provides information on the implicit effects triggered by such stimuli.

The Nencki Affective Picture System (NAPS): a Children-Rated Subset

Emotion research in children should make use of emotional stimuli ideally coming from children-rated databases. However, most of the works in this area use adult-rated stimuli databases or a collection of stimuli taken from the Internet or from unidentified sources without any standardization procedure or content control for children population. These issues result in an overall lack of control over the kind of emotion to be elicited, leading to limited results. Therefore, in this work, a children-rated picture subset taken from the adult-rated Nencki Affective Picture System (NAPS) set is proposed as a stimuli database for emotion research in children. The NAPS is a standardized set of 1356 realistic, high-quality photographs classified into five categories (people, faces, animals, objects, and landscapes), and up to now, normative ratings were only collected in an adult population. The proposed subset in this work contains 1128 pictures taken from the original database which are developmentally appropriate for children based on different criteria and an expert’s judgment procedure. Affective ratings were collected from a sample of 266 children 8–12 years old. With this work, both the availability and quality of affective stimuli for the study of emotion in children are directly improved.

From Abstract Symbols to Emotional (In-)Sights: An Eye Tracking Study on the Effects of Emotional Vignettes and Pictures.

Reading is known to be a highly complex, emotion-inducing process, usually involving connected and cohesive sequences of sentences and paragraphs. However, most empirical results, especially from studies using eye tracking, are either restricted to simple linguistic materials (e.g., isolated words, single sentences) or disregard valence-driven effects. The present study addressed the need for ecologically valid stimuli by examining the emotion potential of and reading behavior in emotional vignettes, often used in applied psychological contexts and discourse comprehension. To allow for a cross-domain comparison in the area of emotion induction, negatively and positively valenced vignettes were constructed based on pre-selected emotional pictures from the Nencki Affective Picture System (NAPS; Marchewka et al., 2014). We collected ratings of perceived valence and arousal for both material groups and recorded eye movements of 42 participants during reading and picture viewing. Linear mixed-effects models were performed to analyze effects of valence (i.e., valence category, valence rating) and stimulus domain (i.e., textual, pictorial) on ratings of perceived valence and arousal, eye movements in reading, and eye movements in picture viewing. Results supported the success of our experimental manipulation: emotionally positive stimuli (i.e., vignettes, pictures) were perceived more positively and less arousing than emotionally negative ones. The cross-domain comparison indicated that vignettes are able to induce stronger valence effects than their pictorial counterparts, no differences between vignettes and pictures regarding effects on perceived arousal were found. Analyses of eye movements in reading replicated results from experiments using isolated words and sentences: perceived positive text valence attracted shorter reading times than perceived negative valence at both the supralexical and lexical level. In line with previous findings, no emotion effects on eye movements in picture viewing were found. This is the first eye tracking study reporting superior valence effects for vignettes compared to pictures and valence-specific effects on eye movements in reading at the supralexical level.

Obsessive-compulsive symptoms are related to reduced awareness of emotional valence

BackgroundThe Seeking Proxies for Internal States (SPIS) model of OCD asserts that obsessive-compulsive (OC) tendencies are associated with attenuated access to internal states. Here we explore the implications of this model for awareness of emotional valence. MethodsIn Study 1, participants with high and low OC tendencies (n = 30 in each group) rated how they felt while viewing different pictures with positive, neutral, or negative valence taken from the International Affective Picture System. Study 2 replicated Study 1 among non-selected participants (n = 99) that rated positive and negative pictures chosen from the recently developed Basic-Emotions Nencki Affective Picture System. In both studies, mean deviation from norm ratings (of each picture system) served as the primary outcome measure. ResultsStudy 1 showed that high OC participants’ mean deviation score was significantly higher, compared with low OC participants, across positive, neutral, and negative pictures (p=.01). Follow-up analyses revealed that while no group difference emerged for mean valence rating (p=.16), groups differed on the mean standard deviation of ratings within each valence category (p=.002). In Study 2, only OC tendencies, not depressive or anxiety symptoms, were positively correlated with mean deviation from norm ratings (p=.026). Dividing the sample to high and low OC groups based on an OC cutoff score yielded similar group differences to those observed in Study 1 (p<.001). LimitationsAnalog samples and a relative small sample size (Study 1). ConclusionsThis study suggests that OC symptoms are associated with reduced awareness of emotional valence, possibly emanating from a noisier emotional perception.

Emotional reactivity and interoceptive sensitivity: Exploring the role of age.

Interoceptive sensitivity (IS) refers to the ability to accurately perceive visceral afferent information, and several prominent theories of emotions suggest that IS is associated with heightened emotional reactivity. Recent evidence has pointed to a decline in IS with age, but there is no consistent evidence of age-related decline in emotional reactivity. This may be because the relationship between IS and emotional reactivity changes with age. To address this hypothesis, we examined the moderating role of age in the association between IS and emotional responses to affect-inducing images. A sample of 65 young adults (mean age = 23.91 years, SD = 4.62) and 32 older adults (mean age = 61.78 years, SD = 8.76) was exposed to affect-inducing images from the Nencki Affective Picture System database and completed a heartbeat perception task. Participants' subjective emotional responses to the images were assessed with questionnaires, and their physiological reactivity was indicated by electrodermal activity, heart rate, and heart rate variability during image viewing. The results revealed that age moderated the association between IS and emotional reactivity, while no significant age differences were found in IS, change in affect, or physiological reactivity. The findings demonstrated that IS was associated with emotional reactivity for young adults but not for older adults, suggesting that young and older adults may differ in their use of internal bodily signals to obtain information about their emotional experience. Consistent with contemporary developments within the affective sciences, the results emphasize the importance of individual differences in emotional experiences.

Age-dependent Reactivity to Affective Images: Evidence for Variation Across Emotion Categories

ABSTRACTBackground: Research on the effect of age on affective reactivity continues to provide inconsistent findings. The present study addresses two potential explanations that may account for these inconsistencies. First, gender may moderate age differences in affective reactivity and second, age differences in affective reactivity may vary according to emotion category. The aim of the present study was therefore to examine age differences in reactions to emotion-inducing images when singling out the effect of gender and emotion category.Methods: A sample of 396 young (mean age = 23.31, SD = 3.70; 66% female) and old (mean age = 66.09, SD = 4.31; 37.5% female) Danish adults rated 105 images from the Nencki Affective Picture System (NAPS) database according to valence and arousal. Images were divided into the three emotion categories of disgust, sadness, and happiness.Results: The findings indicate that age-group influenced affective reactivity, but there was no indication of an an interaction between age-group and gender. Going beyond previous studies, the findings demonstrate that the effect of age-group on affective reactivity varies according to emotion category.Conclusion: The results highlight the importance of considering emotion category in studies of age differences in affective reactivity.

The influence of rightward and leftward spatial deviations of spatial attention on emotional picture recognition

ABSTRACTObjectives: Several studies have reported that positive emotions are primarily mediated by the left hemisphere and negative emotions by the right hemisphere. Since each hemisphere primarily allocates attention toward the contralateral hemispace, we wanted to learn how inducing a spatial attentional orienting bias to right and left egocentric hemispace might influence the recognition and perception of visually presented emotional scenes.Method: Participants were 42 healthy, right-handed young adults. To induce a directional change in spatial attention, we used a horizontal prism adaptation (PA) method that trains participants to allocate attention in the opposite direction to the prism-induced deviation. After each PA, participants evaluated a set of affective (positive/neutral/negative) pictures from the Nencki Affective Picture System. Responses in each emotional category and reaction times were recorded and analyzed.Results: There was no PA effects on reaction times between the experimental conditions. However, when compared to the control condition, both rightward and leftward PA resulted in a reduction of correctly recognized positive emotions as well as altering the perception of neutral and positive pictures as more emotionally negative.Conclusions: The results do not support the proposed left–right spatial attentional valence hypothesis. The reason why PA in both directions negatively altered emotion perception is not known. However, a portion of the dorsal visual stream, the parietal lobes, and especially the right parietal lobe, are critical for mediating horizontal egocentric spatial attention. The right hemisphere also mediates negative emotions, and the activation of this right hemispheric attention network may have induced the changes in perception found in this study. However, future studies are needed to further test this hypothesis.

Affective auditory stimulus database: An expanded version of the International Affective Digitized Sounds (IADS-E).

Using appropriate stimuli to evoke emotions is especially important for researching emotion. Psychologists have provided several standardized affective stimulus databases-such as the International Affective Picture System (IAPS) and the Nencki Affective Picture System (NAPS) as visual stimulus databases, as well as the International Affective Digitized Sounds (IADS) and the Montreal Affective Voices as auditory stimulus databases for emotional experiments. However, considering the limitations of the existing auditory stimulus database studies, research using auditory stimuli is relatively limited compared with the studies using visual stimuli. First, the number of sample sounds is limited, making it difficult to equate across emotional conditions and semantic categories. Second, some artificially created materials (music or human voice) may fail to accurately drive the intended emotional processes. Our principal aim was to expand existing auditory affective sample database to sufficiently cover natural sounds. We asked 207 participants to rate 935 sounds (including the sounds from the IADS-2) using the Self-Assessment Manikin (SAM) and three basic-emotion rating scales. The results showed that emotions in sounds can be distinguished on the affective rating scales, and the stability of the evaluations of sounds revealed that we have successfully provided a larger corpus of natural, emotionally evocative auditory stimuli, covering a wide range of semantic categories. Our expanded, standardized sound sample database may promote a wide range of research in auditory systems and the possible interactions with other sensory modalities, encouraging direct reliable comparisons of outcomes from different researchers in the field of psychology.

Nencki Affective Picture System: Cross-Cultural Study in Europe and Iran.

Although emotions have been assumed conventionally to be universal, recent studies have suggested that various aspects of emotions may be mediated by cultural background. The purpose of our research was to test these contradictory views, in the case of the subjective evaluation of visual affective stimuli. We also sought to validate the recently introduced Nencki Affective Picture System (NAPS) database on a different cultural group. Since there has been, to date, no attempt to compare the emotions of a culturally distinct sample of Iranians with those of Europeans, subjective ratings were collected from 40 Iranians and 39 Europeans. Each cultural group was asked separately to provide normative affective ratings and classify pictures according to discrete emotions. The results were analyzed to identify cultural differences in the ratings of individual images. One hundred and seventy NAPS pictures were rated with regard to the intensity of the basic emotions (happiness, sadness, fear, surprise, anger, and disgust) they elicited, as well as in terms of affective dimensions (valence and arousal). Contrary to previous studies using the International Affective Picture System, our results for Europeans and Iranians show that neither the ratings for affective dimensions nor for basic emotions differed across cultural groups. In both cultural groups, the relationship between valence and arousal ratings could be best described by a classical boomerang-shaped function. However, the content of the pictures (animals, faces, landscapes, objects, or people) had a significant effect on the ratings for valence and arousal. These findings indicate that further studies in cross-cultural affective research should control for the content of stimuli.

Arousal Rather than Basic Emotions Influence Long-Term Recognition Memory in Humans.

Emotion can influence various cognitive processes, however its impact on memory has been traditionally studied over relatively short retention periods and in line with dimensional models of affect. The present study aimed to investigate emotional effects on long-term recognition memory according to a combined framework of affective dimensions and basic emotions. Images selected from the Nencki Affective Picture System were rated on the scale of affective dimensions and basic emotions. After 6 months, subjects took part in a surprise recognition test during an fMRI session. The more negative the pictures the better they were remembered, but also the more false recognitions they provoked. Similar effects were found for the arousal dimension. Recognition success was greater for pictures with lower intensity of happiness and with higher intensity of surprise, sadness, fear, and disgust. Consecutive fMRI analyses showed a significant activation for remembered (recognized) vs. forgotten (not recognized) images in anterior cingulate and bilateral anterior insula as well as in bilateral caudate nuclei and right thalamus. Further, arousal was found to be the only subjective rating significantly modulating brain activation. Higher subjective arousal evoked higher activation associated with memory recognition in the right caudate and the left cingulate gyrus. Notably, no significant modulation was observed for other subjective ratings, including basic emotion intensities. These results emphasize the crucial role of arousal for long-term recognition memory and support the hypothesis that the memorized material, over time, becomes stored in a distributed cortical network including the core salience network and basal ganglia.

Social and nonsocial affective processing in schizophrenia — An ERP study

BackgroundDespite social cognitive dysfunction that may be observed in patients with schizophrenia, the knowledge about social and nonsocial affective processing in schizophrenia is scant. The aim of this study was to examine neurophysiological and behavioural responses to neutral and negative stimuli with (faces, people) and without (animals, objects) social content in schizophrenia. MethodsTwenty-six patients with schizophrenia (SCZ) and 21 healthy controls (HC) completed a visual oddball paradigm with either negative or neutral pictures from the Nencki Affective Picture System (NAPS) as targets while EEG was recorded. Half of the stimuli within each category presented social content (faces, people). ResultsNegative stimuli with social content produced lower N2 amplitude and higher mean LPP than any other type of stimuli in both groups. Despite differences in behavioural ratings and alterations in ERP processing of affective stimuli (lack of EPN differentiation, decreased P3 to neutral stimuli) SCZ were still able to respond to specific categories of stimuli similarly to HC. ConclusionsThe pattern of results suggests that with no additional emotion-related task demands patients with schizophrenia may present similar attentional engagement with negative social stimuli as healthy controls.

Erratum to: Characterization of the Nencki Affective Picture System by discrete emotional categories (NAPS BE).

Erratum to: Behav Res 10.3758/s13428-015-0620-1 The corresponding authors would like to point out that they have separate e-mail addresses: m.riegel@nencki.gov.pl (M. Riegel) and a.marchewka@nencki.gov.pl (A. Marchewka). Additionally, the corresponding authors would like to indicate that the NAPS BE system is freely accessible to the scientific community for noncommercial use by request at http://naps.nencki.gov.pl. The mean ratings of basic emotions for each picture and the results of basic emotion classification are also provided as supplementary materials (Table S2) to this erratum.

Erotic subset for the Nencki Affective Picture System (NAPS ERO): cross-sexual comparison study.

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 http://naps.nencki.gov.pl.

Characterization of the Nencki Affective Picture System by discrete emotional categories (NAPS BE).

The Nencki Affective Picture System (NAPS; Marchewka, Żurawski, Jednoróg, & Grabowska, Behavior Research Methods, 2014) is a standardized set of 1,356 realistic, high-quality photographs divided into five categories (people, faces, animals, objects, and landscapes). NAPS has been primarily standardized along the affective dimensions of valence, arousal, and approach–avoidance, yet the characteristics of discrete emotions expressed by the images have not been investigated thus far. The aim of the present study was to collect normative ratings according to categorical models of emotions. A subset of 510 images from the original NAPS set was selected in order to proportionally cover the whole dimensional affective space. Among these, using three available classification methods, we identified images eliciting distinguishable discrete emotions. We introduce the basic-emotion normative ratings for the Nencki Affective Picture System (NAPS BE), which will allow researchers to control and manipulate stimulus properties specifically for their experimental questions of interest. The NAPS BE system is freely accessible to the scientific community for noncommercial use as supplementary materials to this article.Electronic supplementary materialThe online version of this article (doi:10.3758/s13428-015-0620-1) contains supplementary material, which is available to authorized users.

The Nencki Affective Picture System (NAPS): Introduction to a novel, standardized, wide-range, high-quality, realistic picture database

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 http://naps.nencki.gov.pl.Electronic supplementary materialThe online version of this article (doi:10.3758/s13428-013-0379-1) contains supplementary material, which is available to authorized users.