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

Abstract

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.

Keywords: Affective ratings; Anger; Arousal; Basic emotion; Disgust; Fear; Happiness; Nencki Affective Picture System; Sadness; Surprise; Valence; Visual stimuli.

Fig. 1

Example screen of the assessment platform for a single image, along with the discrete and dimensional scales

Fig. 2

Distributions of the ratings of discrete emotion categories (happiness, sadness, fear, surprise, anger, and disgust), together with the medians of the respective distributions (dotted lines), for the negative (left), neutral (middle), and positive (right) pictures in NAPS BE

Fig. 3

A sample of standardized images classified as representing each basic emotion within the content category of animals

Fig. 4

Numbers of pictures expressing each discrete emotional category, classified on the basis of confidence intervals as expressing pure, blended, and undifferentiated emotions

Fig. 5

Ratings of the pictures classified on the basis of the confidence interval as basic, blended, and undifferentiated emotions in the space of the affective dimensions: valence and arousal

Fig. 6

Mean intensities of all discrete emotion categories, as a function of all semantic categories and all valence classes. ^*Significant differences between the mean intensities of particular basic emotions of content categories, marked with relevant colors: animals = blue, faces = red, landscapes = green, objects = purple, and people = orange; p < .05