Brazilian norms for the International Affective Picture System (IAPS): brief report

Abstracts

O presente artigo apresenta valores normativos brasileiros para o International Affective Picture System (IAPS), um conjunto de estímulos com potencial de eliciar emoções amplamente utilizado na investigação experimental. Também são apresentados aqui os resultados da comparação entre as respostas de homens e mulheres brasileiros. Um total de 1062 universitários brasileiros (364 homens e 698 mulheres) foram incluídos e avaliaram as 707 fotografias do IAPS nas dimensões prazer, alerta e dominância, utilizando o mesmo procedimento do estudo normativo original realizado por Lang et al. nos Estados Unidos, em 1999.

Emoção; valência afetiva; alerta; dominância

Este artículo presenta valores normativos brasileños para el International Affective System (IAPS), un conjunto de estímulos con potencial de poner al descubierto emociones, que es ampliamente utilizado en la investigación experimental. Además, se presentan los resultados de la comparación entre las respuestas de hombres y mujeres brasileños. Un total de 1062 universitarios brasileños (364 hombres y 698 mujeres) han sido incluidos y evaluaron las 707 diapositivas del IAPS en los niveles placer, alerta y dominancia, utilizando el mismo procedimiento del estudio normativo original realizado por Lang et al. en Estados Unidos, en 1999.

Emoción; valencia afectiva; alerta; dominancia

ORIGINAL ARTICLE

Brazilian norms for the International Affective Picture System (IAPS): brief report

Normas brasileñas para el International Affective Picture System (IAPS): breve comunicación

Rafaela Larsen Ribeiro^I; Sabine Pompéia^II; Orlando Francisco Amodeo Bueno^I

^IAssociate Professor, Psychobiology Department, Universidade Federal de São Paulo (UNIFESP), São Paulo SP — Brazil

^IIPhD, Psychobiology Department, Universidade Federal de São Paulo (UNIFESP), São Paulo SP — Brazil

^{Correspondence}

ABSTRACT

The present article provides Brazilian norms for the International Affective Picture System (IAPS), a set of affectively salient photographic slides widely used in experimental research. In addition, the article compares the responses of male and female volunteers to the system in Brazil. A total of 1062 Brazilian university students (364 men and 698 women) were included, and they rated 707 pictures from the IAPS in terms of valence, arousal, and dominance, following the methodology of the original normative study carried out by Lang et al. in the United States in 1999.

Keywords: Emotion, affective valence, arousal, dominance.

RESUMEN

Este artículo presenta valores normativos brasileños para el International Affective Picture System (IAPS), un conjunto de estímulos con potencial de poner al descubierto emociones, que es ampliamente utilizado en la investigación experimental. Además, se presentan los resultados de la comparación entre las respuestas de hombres y mujeres brasileños. Un total de 1062 universitarios brasileños (364 hombres y 698 mujeres) han sido incluidos y evaluaron las 707 diapositivas del IAPS en los niveles placer, alerta y dominancia, utilizando el mismo procedimiento del estudio normativo original realizado por Lang et al. en Estados Unidos, en 1999.

Palabras clave: Emoción, valencia afectiva, alerta, dominancia.

INTRODUCTION

Although there is no consensus definition of the term emotion, most authors agree that it constitutes a complex phenomenon that exert a powerful influence on behavior, facilitates adaptation to the environment, involves multiple responses and is highly variable in its psycho-physiological composition.¹ Due to this complexity in the manifestations of emotions, particularly in Man, recent studies have emphasized the need to find reliable measures and stimuli for controlled investigation of affective processes.

Procedures appropriate for inducing emotional states in the laboratory setting should be characterized by being built on an underlying theoretical construct and by the use of standardized stimuli. The most extensive set of stimuli that satisfies these requirements is the International Affective Picture System (IAPS).²

The IAPS includes hundreds of high-resolution colored photographs that feature many aspects of real life (sports, fashion, landscapes, violence etc.) capable of inducing a range of emotional states which can be easily presented in the experimental laboratory context, thus allowing precise control over the timing and duration of exposure.³ Emotional responses to these and other stimuli may be appraised subjectively using scales, or scored objectively by physiological measures such as facial expression, visceral reactivity or behavioral responses.⁴ The affective evaluation used for subjective rating of emotions in response to the IAPS photographs consists of the evaluation of valence or pleasure (pleasant-unpleasant) and arousal (aroused-relaxed).⁵ A third dimension, dominance, is highly correlated with the pleasure dimension and has also been used to evaluate these stimuli.² These three dimensions have long been described as crucial to the way humans organize their evaluative responses to a wide group of perceptual stimuli.⁵

The IAPS stimuli are subjectively rated using the Self-Assessment Manikin (SAM),⁶ which includes five characters or figures for each dimension. For instance, the scale for rating the pleasure associated with viewing a photograph varies from a smiling, happy figure at one extreme to the fifth character at the other extreme showing an unhappy face, with varying levels of "happiness" in between. Subjects respond to photographs by marking X on one of the five figures on each scale, or between two of them, thus leading to a 9-point scale for each dimension. Ratings are made in such a way that 9 is the highest score on each dimension and stands for high levels of pleasure, arousal or dominance, whereas 1 is the lowest score on each dimension: low pleasure, low arousal and low dominance. The SAM may be used to rate emotional responses to a variety of stimuli for several types of experimental subjects, since it provides an easy method of reporting affective experiences. According to its authors,5 the SAM is a reliable and valid instrument because the pleasure and arousal ratings are highly correlated with measures of affective evaluations obtained on the basis of the Differential Semantic Scale devised by Mehrabian & Russel (1974), a verbal system for describing emotional stimuli.

The aim of the present study was to determine Brazilian norms for evaluating subjective affective responses to the IAPS photographs following the methodology of the original study by Lang et al.² and to compare responses by men and women in Brazil.

This knowledge of responses to IAPS stimuli by the Brazilian population is crucial if this set of photographs is to be used in research to study emotional responses both in normal subjects as in clinical populations for the diagnosis and evaluation of affective dysfunctions. Therefore, it is important that this instrument that evaluates emotional answers becomes available to all the researchers and physicians of the area.

METHOD

Subjects

One thousand and sixty two (1062) university students (364 men and 698 women) drawn from different courses (Psychology, Law, Pharmacy, Medicine, Industrial Design, Advertising and Marketing, Biomedicine, Dentistry, Civil Engineering) from public and private universities in Curitiba and São Paulo, aged 18-35 (average age 22.8 ± 4.6) who had Portuguese as their native tongue. The selection of subjects was based on the contacts previously established, concentrating in institutions that had allowed the use of their classrooms. The exclusion criteria included subjects who did not use glasses to correct vision and those who did not have the Portuguese as their first language. There were no losses in the sample.

Material

Seven hundred and seven photographs from sets 1-12 of the IAPS (the sets available at the beginning of this study) originally described in Lang et al.²

Procedure

The methodology, classification and analysis of the results followed those of the original work² except for the number of photographs tested per session (around 30 in contrast with Lang's original sets of around 60). These subsets of approximately 30 were obtained by randomly dividing each of Lang's sets in two. The reason for this reduced number of photographs per session was the time made available by the institutions where the data were collected (30 minutes).

Volunteers rated all photographs on three dimensions (valence, arousal and dominance) by choosing the appropriate figure from the ScanSAM (paper and pen version). The polarity of these scales was alternated for different experimental subjects. In addition to the 30 IAPS photographs classified in each session, the same three photographs used by Lang were employed as examples and their emotional content rated on a practice sheet. Each experimental session included the projection of slides containing the instructions and showing illustrated examples of SAM scores for each dimension (pleasure, arousal and dominance).

Each session began with a preparatory slide showing the number of the next photograph to be presented (from 1 to 30) for 5 s. Then the photograph being rated was individually projected onto the screen for 5 s. During the following 10 s, during which no slide was projected, subjects were asked to rate the last photograph seen on the three dimensions (pleasure, arousal and dominance). The experimental sessions were held in classes containing 8-40 students with appropriate lighting for viewing slides and the maximum size of the image projected was 1.20 m x 1.50 m (approximately 4 x 5 ft).

In each of the cities where the study was conducted, a similar number of subjects classified photographs in the two subsets corresponding to each full set in the original methodology; for each photograph we determined the mean and standard-deviation of the affective evaluations by all subjects viewing that photograph, and for men and women separately, along each dimension.

Data of men and women were compared by Student t tests. The significance level adopted was 5%.

RESULTS

Presentation of the results (normative values for the Brazilian adaptation) follows the lines of the original work² and the only standardization conducted in another country (Spain).^1,7 Means and standard-deviations are shown for all variables (each of the three dimensions for each photograph), for the total number of subjects and separately for men and women. With the international classification number for each photograph, i.e. the number for the photograph within the whole IAPS set, there is also a brief description of each figure (e.g.: Figure 1660 — Description: Gorilla). These normative values for the Brazilian adaptation may be found at the website www.unifesp.br/dpsicobio/adap/adapta.htm, as well as instructions from the original work, the translation employed here and some example photographs.

In addition to the fact that the mean values for the standard-deviation of each resultant set of photographs shown to the Brazilian samples had been, in general, less than or equivalent to the values obtained in the North American standardization (data not shown), indicating a less or equal variation in the subjects' answers, there were no differences in results obtained due to the reduced number (from 60 to 30) of visual stimuli per experimental session.

In relation to inter-gender comparisons within the Brazilian sample (table 1), there were no significant differences within the dimensions of pleasure and arousal, although the Brazilian women attributed less dominance to photographs than the men (ps ≤ 0.04). Neither were there significant differences in terms of the Brazilian classifications for the dimensions of pleasure, arousal and genre dominance for pleasant (P — pleasure > 6.0), unpleasant (U — pleasure < 4.0) and neutral (N — pleasure between 4.0 and 6.0) pictures (table 2).

DISCUSSION

Although there were no significant differences on the arousal dimension, in relation to men women attributed higher arousal values to the unpleasant photographs (e.g. mutilations and weapons) and rated lower levels of dominance and control over these stimuli. In contrast, men attributed a higher arousal level to pleasant photographs (e.g. erotic photographs) than did women. These differences in affective reports between men and women seem to reflect different motivational emphases between genders³ which were also reported in the USA³ and Spain.^1,7

It is expected that the normative IAPS scores for the Brazilian population as presented here will be used in investigation of cognitive processes in normal subjects and populations with neurological/affective dysfunctions. However, pilot studies should be conducted for each target population to determine adaptation of the selected stimuli for little is known about how factors such as disease, age, schooling, etc. interfere in the subjective evaluation of emotional stimuli.

Acknowledgement

FAPESP (ref. no. 99/09951-9) and AFIP for financial support. Professors and students of the universities UFPR, UNICENP and UNIANDRADE in Curitiba, and UNIFESP, USM, UNISA, UNIP-Tatuapé, Faculdades Oswaldo Cruz and Faculdades Paulistanas (FAPA) in São Paulo, who assisted data collection.

REFERENCES

Received on February 9, 2004.

Revised on April 23, 2004.

Approved on July 21, 2004.

• 1. Moltó J, Montañés S, Poy R, Segarra P, Pastor MC, Tormo, MP, et al. Un nuevo método para el estudio experimental de las emociones: el International Affective Photograph System (IAPS). Adaptación española. Revista de Psicologia General y Aplicada 1999;52:55-87.
• 2. Lang PJ, Bradley MM, Cuthbert BN. International affective picture system (IAPS): instruction manual and affective ratings. Technical Report A-4. The Center for Research in Psychophysiology, University of Florida; 1999.
• 3. Bradley MM, Lang PJ. Measuring emotion: behavior, feeling and physiology. In: Lane R, Nadel L, eds. Cognitive neuroscience of emotion. New York: Oxford University Press; 2000. p. 242-76.
• 4. Lang PJ. Cognition in emotion: concept and action. In: Izard CE, Kagan J, Zajonc RB, eds. Emotions, cognition, and behavior. New York: Cambridge University Press; 1984. p. 192-226.
• 5. Bradley MM, Lang PJ. Measuring emotion: the self-assessment manikin and the semantic differential. J Behav Ther Exp Psychiatry 1994;25:49-59.
• 6. Lang PJ. Behavioral treatment and biobehavioral assessment: computer applications. In: Sidowski JB, Johnson JH, Williams TA, eds. Technology in mental health care delivery systems. Norwood, NJ: Ablex; 1980. p.119-37.
• 7. Vila S, Sánchez M, Ramírez I, Fernández MC, Cobos P, Rodríguez S, et al. El Sistema Internacional de Imágenes Afectivas (IAPS). Adaptación española. Segunda parte. Revista de Psicología General y Aplicada 2001;54:635-57.

Publication Dates

• Publication in this collection
  13 Sept 2005
• Date of issue
  Aug 2004

History

• Accepted
  21 July 2004
• Received
  09 Feb 2004
• Reviewed
  23 Apr 2004