In Study 1, we aimed to construct the SFIP by selecting photographs that were fear- and/or arousal-inducing in people who suffer from social, small-animal, or blood/injection fear. The construction of the SFIP was done by balancing two goals: The photographs had to trigger increased fear and/or arousal in one of the three fear groups, while at the same time eliciting less intense fear and/or arousal in the other fearful and nonfearful individuals.
Our participants were recruited from a large sample of students from Warsaw universities (N = 1,671) who completed an online version of the 92-item FSS-III (Wolpe & Lang, 1964). Participants were asked to evaluate their subjective experience of fear for each FSS item on a 5-point Likert-type scale ranging from 1 (not at all) to 5 (very much). Replicating previous findings (for a review, see Arrindell et al., 1991), factor analyses showed acceptable fit of the three-factor solution. One factor contained 20 items reflecting social anxiety or fear of failure (e.g., speaking in public, failing, and being teased), the second included 12 items assessing fear of blood/injection/injury (e.g., open wounds, dead people, and receiving injections), and the third included seven items reflecting fear of small animals (e.g., bats, harmless spiders, flying insects, and harmless snakes). Participants scoring greater than or equal to one standard deviation above the mean (≥+1 SD) on one of these factors and less than one standard deviation above the mean (<+1 SD) on the other two factors were assigned to an appropriate fear group: small-animal fear (SA), blood/injection/injury fear (BII), or social/failure fear (SOC). Those scoring less than or equal to the mean on all three factors were preselected as the nonfearful controls (CON). A group of 117 preselected candidates (26 male [♂], 91 female [♀]) participated in the picture-rating session, including 22 control (14♂, 8♀), 35 social/failure fear (6♂, 29♀), 34 small-animal fear (3♂, 31♀), and 26 blood/injection fear (3♂, 23♀) individuals. Descriptive statistics for the individual FSS subscales and the total scores are presented in Table 1. When compared to the other groups, the small-animal fear group showed significantly higher FSS Small Animal subscale scores, the blood fear group revealed higher FSS Blood/Injection subscale scores, and the social fear group higher FSS Social/Failure subscale scores, ts > 10, ps < .001. All fear groups scored significantly higher on their fear-specific FSS subscales than on the other scales, ts > 7, ps < .001. The control group showed significantly higher scores on the FSS Blood and Social/Failure subscales than on the FSS Small Animal subscale, ts(21) > 2.5, ps < .05, and no differences between the FSS Blood and Small Animal subscales, t(21) = 1.58, n.s.
Participants were presented with a total of 400 color pictures. 151 photographs were taken from Flickr (https://www.flickr.com/) under a Creative Commons license (https://www.flickr.com/creativecommons/) or taken by the coauthors. In addition, 12 images were taken from the IAPS (Lang et al., 2008), seven images from GAPED (Dan-Glauser & Scherer, 2011), 170 images from NAPS (Marchewka et al., 2014; Riegel et al., 2016; Wierzba et al., 2015), and 60 images from WSEFEP (Olszanowski et al., 2015). The selected pictures could be divided into five categories: blood/injection (N = 80 from NAPS), small animals (N = 80, including seven GAPED and four IAPS), social exposure (N = 80, including 18 NAPS and four IAPS), angry faces (N = 30 from WSEFEP), and neutral (N = 130, including 74 NAPS, 30 WSEFEP, and four IAPS; see Fig. 1). A picture was selected for the social-exposure, blood/injection, or small-animal category if its content referred to the items of the corresponding FSS subscale. The social-exposure category included photographs illustrating items from the FSS Social/Failure subscale (e.g., speaking in public, being teased, or taking an exam). The blood/injection category consisted of photographs depicting the FSS Blood/Injection subscale’s items (e.g., open wounds, dead people, or receiving injections), and the small-animal picture category included the FSS Small Animal subscale’s objects (e.g., bats, spiders, flying insects, or snakes). The neutral category included pictures of animals, objects, people, faces, plants, and landscapes. The images were resized and cropped using proportions of 4:3 (portrait) or 3:4 (landscape). All stimuli were divided into two equal sets of 200 images balanced by content. Set 1 was evaluated by 61, and Set 2 by 56, participants.
Prior to the computerized experimental procedure that was run in the laboratory, participants were familiarized with examples of the images, and asked to provide written informed consent. Each participant judged 200 pictures presented pseudorandomly with the restriction that pictures from the same category could not occur on three consecutive trials. During the rating session each picture was presented for 3 s in the middle of the 21,5-in. monitor covering approximately 65 % of the screen space. After the offset of the slide, the smaller version of the picture remained available on the top of the screen until it was evaluated on all of the three scales: fear, arousal, and valence. First, the participant was asked to evaluate his/her subjective experience of fear on a scale ranging from 1 (not at all) to 5 (very much). Following the fear decision, each participant rated his or her subjective experience of valence (displeasure–pleasure) and arousal on a computerized version of the 9-point Likert scale of the Self-Assessment Manikin—a popular pictorial self-report technique used to directly assess the intensity and the direction of affective reactions to various kinds of stimuli (Bradley & Lang, 1994). The arousal scale ranged from 1 (calm) to 9 (aroused), and the valence scale ranged from 1 (unpleasant) to 9 (pleasant). The rating session lasted approximately 40 min and was conducted on standard PC computers with 21.5-in. LCD computer monitors. Stimulus presentation and data acquisition were based on in-house software. All responses were analyzed using the SPSS package. The study protocol was approved by the local ethics committee and conformed to Standard 8 of the American Psychological Association’s Ethical Principles for Psychologists and Code of Conduct.
SFIP construction and statistical methods
From the initial 400 photographs, 288 pictures were selected for the SFIP on the basis of their content validity. An image was included into one of the three phobia-subsets if it was rated as more fear- and/or arousal-evoking by the corresponding fear group than by the remaining groups. Considering these criteria, 172 fear-relevant pictures were selected: 80 blood/injection (alive injured or dead human or animal bodies, or their isolated parts), 40 social-exposure scenes (microphones, people sweating, taking an exam, or giving a lecture), 30 angry faces, and 22 small-animal pictures (i.e., spiders and bugs). Since the ratings in the latter category were characterized by high variance and some subcategories of the small animals did not discriminate between the small-animal fear and the other fear groups in the expected direction, in the final SFIP version we included only photographs depicting spiders and bugs. The picture pool was completed with 116 neutral photographs (e.g., objects, people, mushrooms, plants, landscapes, animals, and 30 neutral faces) that did not evoke fear in any of the four experimental groups (i.e., fear M < 2.0, or less than a little). The initial set of 400 pictures and the resulting set of 288 pictures selected to the SFIP were analyzed separately. In each case, independent group t test, means, standard deviations, and Cohen’s d are reported in the Results section to describe the between-group effects separately for each picture category.
All fear-relevant picture categories obtained higher fear ratings in the corresponding fear groups than among the nonfearful controls, ts ≥ 3.6, ps < .001 (see Table 2 and Fig. 2). Here, the effect size was largest for the blood pictures (BII > CON: d = 2.10), followed by photographs of small animals (SA > CON: d = 1.77), social exposure (SOC > CON: d = 1.39), and angry faces (SOC > CON: d = 1.09). The evaluation of neutral pictures revealed higher fear ratings in fearful than in control individuals, ts > 2.4, ps < .05, effect sizes ranging from 0.63 (SA > CON) to 0.82 (BII > CON). Comparing the three fear groups revealed that higher fear ratings were found for small-animal pictures in the SA than in the SOC and BII groups, t(67) = 3.52, p < .001, d = 0.84, and t(58) = 1.80, p = .078, d = 0.45, respectively. Blood/injection pictures were rated as being more fear-evoking by the BII than by the SOC and SA groups, ts > 3, ps < .01 (ds = 0.94 [BII > SOC] and 0.79 [BII > SA]). Social-fearful participants rated pictures of social exposure and angry faces as being more fear-evoking than did the SA group, ts > 2, ps < .05, moderate effect sizes (i.e., between 0.5 and 0.7), but not than the BII group, ts(59) < 1.5, ps > .1.
Mirroring the fear ratings, arousal assessments for the fear-relevant pictures were higher in the corresponding fear groups than in the control participants, ts ≥ 4.0, ps < .001 (see Table 2 and Fig. 3). The effect sizes were largest for the blood/injection picture category (BII > CON: d = 1.81), followed by pictures depicting small animals (SA > CON: d = 1.31), social-exposure scenes (SOC > CON: d = 1.21), and angry faces (SOC > CON: d = 1.15). When compared to the nonfearful controls, even the neutral pictures were rated as being more arousing in the SOC and BII groups, ts > 2.5, ps < .05, moderate effect sizes, but not in the SA group, t(54) < 1, p > .1. For photographs of small animals, arousal was rated similarly in all fear groups, ts < 1, ps > .1. Blood/injection pictures were rated as being more arousing in the BII than in the SA group, t(58) = 2.75, p < .01, d = 0.72, but not than in the SOC group, t(59) = 1.28, p > .1. Pictures of social exposure and angry faces were rated as being more arousing in the SOC than in the SA group, ts > 3, ps < .01 (ds = 0.73 and 0.82, respectively). The arousal ratings were higher in the SOC than in the BII group for pictures of angry faces, t(59) = 1.96, p = .05, d = 0.51, but not for social-exposure scenes, t(59) < 1, p > .1.
The three fear groups evaluated their target pictures as being more unpleasant than did the controls, ts > 4, ps < .001: blood photographs (BII > CON: d = 1.67), small-animal pictures (SA > CON: d = 1.50), social-exposure scenes (SOC > CON: d = 1.28), and angry faces (SOC > CON: d = 1.12; see Table 2 and Fig. 4). Neutral pictures were assessed with similar valence ratings by the fear and nonfearful control groups, ts < 1.2, ps > .1. Photographs of small animals were experienced as being more unpleasant in the SA group than in the SOC and BII groups, ts > 2, ps < .05 (ds = 0.82 and 0.55, respectively). Blood/injection pictures were assessed as being more unpleasant in the BII than in the other fear groups, ts ≥ 2, ps ≤ .05 (ds = 0.84 [BII > SOC] and [BII > SA]). Pictures of social exposure were rated as being more unpleasant in the SOC than in the SA and BII groups, ts ≥ 2, ps < .05, moderate effect sizes. Images of angry faces were evaluated as being more unpleasant in the SOC than in the SA group, t(67) = 2.02, p < .05, d = 0.75, but not than in the BII group, t(59) = 1.66, p = .10.
Ratings for selected social-exposure pictures
Selecting the social-exposure pictures that best discriminated between the social fear and the other fear groups increased their discrimination abilities. The selected subset was rated as being more fear-evoking, arousing, and unpleasant by social fearful than by nonfearful and small-animal fearful participants, ts(55) > 4.4, ps < .001, ds ≥ 1.2, and ts(67) > 3.5, ps < .001, ds > 0.8, respectively. When compared to the BII group, social-fearful participants rated this set as being more unpleasant, t(59) = 2.75, p < .01, d = 0.73, but similarly arousing and fear-evoking, ts(59) < 1.6, ps > .1 (see Table 2, bottom). In the social fear group, this set of social-exposure pictures was rated as being more arousing and fear-evoking than pictures depicting angry faces, t(35) = 2.4, p < .05, and t(35) = 2.0, p = .056, for fear and arousal ratings, respectively.
Ratings for pictures of spiders and bugs
The pictures of spiders and bugs selected from the small-animal set (see the Discussion below) differentiated the SA from the other groups. Here, SA participants rated these pictures as being more fear-evoking, arousing, and unpleasant than did the nonfearful controls, ts(54) > 5, ps < .001, ds > 0.9. As compared to the SOC and BII groups, the SA group found these pictures more unpleasant, ts > 2.5, ps < .05 (ds = 0.80 [SA > SOC] and 0.68 [SA > BII]), and fear-evoking, ts ≥ 2.5, ps < .05 (ds = 0.84 [SA > SOC] and 0.65 [SA > BII]), but similarly arousing, ts < 1.2, ps > .1.
In Study 1, we selected and validated a set of stimuli for studying fear responses in social and specific (blood and spider) fearful individuals. The results of this study revealed that pictures depicting small animal, as well as social-exposure and blood/injection scene, were assessed as being more fear-evoking, arousing, and unpleasant by the corresponding fear groups than by nonfearful controls. Interestingly, neutral pictures were also assessed as being more arousing and fear-evoking in the social and blood fear groups, suggesting that in a fear-relevant context these participants might tend to assess all of the stimulus materials as being more arousing and fear-evoking, a tendency that might have affected the results of our validation study. As expected, blood/injection pictures were rated as being more unpleasant and fear-evoking in the blood/injection than in the other fear groups. Fear and valence (but not arousal) ratings for small-animal pictures were also shown to differentiate between the small-animal and the other fear groups. Pictures depicting social-exposure scenes were rated as being more arousing, fear-evoking, and unpleasant in the social than in the small-animal fearful participants. At the same time, the social and blood/injection fear groups did not differ in their arousal and fear ratings for social-exposure pictures.
Overall, our findings revealed several weaknesses of the initially selected picture set. First, the subset of small-animal pictures was assessed as being similarly arousing by the three fear groups, and a thorough examination revealed that the group effects were unstable across different subcategories of small animals, suggesting that small-animal phobia cannot be treated homogeneously. As a consequence, we decided that the resulting picture set would only include the pictures depicting spiders and bugs that were shown to best discriminate between the small-animal and the other fear groups (see Table 2). Second, we found no difference between the social and BII fear groups with regard to their arousal and fear ratings for social-exposure pictures. This was mostly related to the fact that the BII individuals were particularly sensitive to those social-exposure photographs that depicted some forms of violence (e.g., being teased or one person bullying another). In fact, previous findings had revealed that BII fearful people avoid violent movies/games due to their association with blood and injuries (Ritz & Meuert, 2014). However, selecting only social-exposure pictures that were assessed with greater fear and/or arousal ratings by social-fearful participants did not meaningfully improve the pictures’ ability to discriminate between the social and blood/injection fear groups. Nonetheless, in the social fear group the selected set of social-exposure pictures was assessed as being more arousing and fear-evoking than the pictures depicting angry faces. Third, the ratings demonstrated that the three fear groups were emotionally more affected by neutral photographs than were the nonfearful controls. Considering the fact that threat was more likely to occur for fearful participants in this study, we suggest that this effect may reflect the greater overall arousal experienced by the fear groups and might be reduced by including a greater number of neutral pictures.