- Email: [email protected]
Physiological responses to trypophobic images and further scale validity of the trypophobia questionnaire
Personality and Individual Differences 108 (2017) 66–68
Contents lists available at ScienceDirect
Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid
Short Communication
Physiological responses to trypophobic images and further scale validity of the trypophobia questionnaire R. Nathan Pipitone ⁎, Brandon Gallegos, Danielle Walters Adams State University, Alamosa, CO 81101, USA
a r t i c l e
i n f o
Article history: Received 16 September 2016 Received in revised form 29 November 2016 Accepted 30 November 2016 Available online xxxx Keywords: Anxiety Fear Human physiology Trypophobia
a b s t r a c t Trypophobia, or the fear of small clusters of objects in close proximity to one another is a unique and recently discovered phenomenon to the scientific literature. Recent work has shown that a small subset of the human population will react adversely to trypophobic images. Although trypophobia at first glance seems irrational, these images might be triggering a primitive threat detection system that has adaptive functionality - trypophobic images share similar spectral characteristics also found among dangerous animals. In the present study, we replicate previous work showing increased levels of discomfort when viewing trypophobic images and also provide further validation for a newly designed questionnaire that measures participants' level of trypophobia. Measuring participant physiology, we then show an increase in two measures of electrodermal activity when participants viewed trypophobic images compared to control images. Our results add to the accumulating literature investigating the adaptive rationale for exhibiting heightened fear responses when viewing trypophobic imagery. © 2016 Elsevier Ltd. All rights reserved.
1. Introduction Trypophobia, or the fear of small clusters of objects in close proximity to each other (commonly elicited from small clusters of holes) is a unique and recently documented phenomenon in the scientific literature (Cole & Wilkins, 2013; Le, Cole, & Wilkins, 2015). Recent work has shown that on average, adults rate trypophobic images as being more uncomfortable to view compared to control images (images that usually depict one large hole), with a small portion (15%) of their sample finding trypophobic images particularly repulsive to view (see Fig. 1 for a trypophobic image example). Cole and Wilkins (2013) also assessed the spectral frequencies of trypophobic images and found them to exhibit high-contrast energy at midrange spatial frequencies. The excess energy at midrange spatial frequencies is also present among images that depict poisonous animals such as the poison dart frog, puffer fish, snakes, spiders (Cole & Wilkins, 2013), and other images found in nature that are generally uncomfortable to view (Fernandez & Wilkins, 2008). While at first glance it may seem irrational to exhibit an adverse reaction to patterns of small clustered objects, these images might be triggering a primitive threat detection system that has adaptive functionality when put into the context of images ⁎ Corresponding author at: Adams State University, Department of Psychology, 208 Edgemont Boulevard, Alamosa, CO 81101, United States. E-mail address: [email protected] (R. Nathan Pipitone).
http://dx.doi.org/10.1016/j.paid.2016.11.068 0191-8869/© 2016 Elsevier Ltd. All rights reserved.
that usually encompass these characteristic visual patterns in the natural world. In the present study, we attempt to replicate work using the exact same stimuli used in Cole and Wilkins (2013), which showed levels of comfort changing as a consequence of viewing trypophobic images. We also incorporate a recently designed Trypophobia Questionnaire (TQ) developed by Le et al. (2015) to assess whether levels of comfort when viewing trypophobic and control images relate to scores on the TQ (i.e., convergent validity). We then investigate discriminant validity of the TQ by collecting participants' level of generalized anxiety to see if TQ scores are independent of generalized anxiety levels. Finally, we assess participants' physiological responses using measures of electrodermal activity (EDA) and heart rate (BPM) when viewing trypophobic and control images. Using physiological measures in conjunction with subjective reports provides a better depiction of participants' emotional state (Bradley & Lang, 2007) and can also provide basic, automatic, and possibly lower-level conscious emotional processing, especially when dealing with evolutionarily threat-relevant stimuli (Shoup-Knox & Pipitone, 2015). Based on previous work which showed lower levels of comfort when viewing trypophobic images and the images sharing similar spatial frequency profiles as dangerous animals, we hypothesize that viewing trypophobic images will elicit a heightened EDA response and changes in BPM compared to control images (BPM has been shown to accelerate during negative emotional states [e.g., Levenson, Ekman, & Friesen, 1990] but also decelerate during unpleasant stimuli processing
R. Nathan Pipitone et al. / Personality and Individual Differences 108 (2017) 66–68
Fig. 1. The Lotus seed head is a well-known trigger for trypophobic individuals. Photograph retrieved from https://commons.wikimedia.org/wiki/File:LOTUS_SEEDPOD. JPG, Author: 3Point141.
[e.g., Bradley & Lang, 2007]). We also assess whether higher physiological responses to trypophobic images exist among participants who score higher on levels of trypophobia, based on the TQ.
67
presentation displayed an array of 50 trypophobic and 50 control images, which alternated during the course of the experiment. These images were the same images from Cole and Wilkins (2013), and contained a variety of living and non-living trypophobic and control pictures. When the participants were ready, a picture of a plain grassy field was shown for 1 min to establish a baseline for all physiological measures. After the baseline session, the slideshow then automatically moved through the images every 12 s, with 7 s of stimulus presentation and a 5-s blank screen in order for participant physiology to return to baseline and so they could rate their level of comfort for each image. During the physiological recording session, participants were asked to provide levels of comfort for each image on a scale from −5 (extremely uncomfortable) to 5 (extremely comfortable) via a self-report survey. Physiological measures were recorded using Biopac Student Lab (BSL) PRO 3.7.7 software. After the data were collected, the signals from the physiological measures were adjusted to reduce noise, drift, and in the case of ECG converted to BPM for heartrate. A 10 Hz high pass filter was applied to the ECG signal. A 0.03 Hz high pass filter was applied to the EDA signal to reduce the effects of tonic drift and to focus on the phasic EDA responses (Braithwaite, Watson, Jones, & Rowe, 2013). We then used BSL PRO 4.0.1 software to select appropriate response time intervals (seconds 1–6) to measure differences in EDA and BPM responses during stimulus presentation. The overall mean and max measures of EDA as well as mean BPM for selected intervals were exported to excel spreadsheets and then transferred to IBM SPSS 23 where statistical analyses could be conducted.
2. Method 3. Results 2.1. Participants Thirty-seven undergraduate students from a university in Southern Colorado were recruited to participate in the present study (16 male, 21 female; mean age = 22.59, SD = 7.96). The study was approved by the University IRB. Participants volunteered to be in the study in exchange for extra credit in their classes. Participants were asked to fill out a demographic questionnaire which contained information about past history of psychological disorders, phobias, anxiety, and any prescribed medication. One participant was excluded because of medical issues, incomplete comfort ratings, and also for abnormal physiological responses during the biofeedback session. Three participants' EDA scores and four participants' BPM scores were removed from analyses because of incomplete responses during the physiological recording sessions. 2.2. Procedure and materials The TQ was administered first, which involved participants looking at two characteristic trypophobic images (an image of a lotus seedpod and a close-up of a honeycomb) and asked to provide responses to 17 questions that surround negative emotional reactions to the images (e.g., feel nervous, feel panicky, feel skin crawl) on a 5-point Likert scale (ranging from not at all to extremely). The TQ has been shown to be a reliable measure of trypophobia (Cronbach's alpha = 0.96), with construct, convergent and discriminant validity being established (Le et al., 2015). Participants then filled out the GAD-7, a seven-item questionnaire that assesses levels of generalized anxiety (Spitzer, Kroenke, Williams, & Lowe, 2006). After the completion of the survey materials, participants had Biopac SS2L and SS57L electrodes attached to the index and middle fingers on their non-dominant hand, wrist, and both ankles with a small application of Signa gel added to foam disposable EL 503 electrodes in order to collect electrodermal activity (EDA) and electrocardiogram (ECG) data. Prior to placement of the electrodes, alcohol swabs were used to clean the skin surface. ECG data was converted into beats per minute (BPM), and EDA was measured in microsiemens (μS) for analysis. Participants then sat in front of a computer monitor where a PowerPoint
Heart rate at the baseline measure fell within a normal range of 49.13–103.72 BPM (M = 77.12, SD = 12.4). Unfiltered electrodermal activity (EDA) at baseline ranged from 1.01 to 42.38 μS (M = 14.7, SD = 9.17). Scores on the TQ indicated that 6 out of 35 participants (17%) of our sample scored above the threshold (scores above 31) for trypophobia (Le et al., 2015). The percentage of individuals with trypophobia is comparable to what Cole and Wilkins (2013) found in their sample. The TQ showed good reliability after removing the two foil items (Cronbach's alpha = 0.887). 3.1. Validity assessment We first sought to replicate previous work (Cole & Wilkins, 2013) that showed lower levels of comfort when viewing trypophobic images. Overall, participants reported lower levels of comfort when viewing trypophobic images (M = 0.99, SD = 2.04) compared to control images of holes (M = 2.48, SD = 1.55), t(35) = −5.95, p b 0.001, d = 0.99. To explore convergent validity, a Pearson correlation was conducted between TQ scores and participants' comfort level when viewing trypophobic and control images. Results showed that higher TQ scores correlated significantly with lower comfort levels when viewing trypophobic images (r = − 0.57, p b 0.001) only; TQ scores were not significantly related to levels of comfort when viewing control images of holes (r = − 0.202, p = 0.2), replicating findings from Le et al. (2015). Our sample included several participants who scored higher on the TQ, which skewed the variable somewhat. Because of this, we log transformed the variable and ran the correlations again. Results showed the same trends: Log TQ scores correlated significantly with lower comfort levels when viewing trypophobic images (r = − 0.61, p b 0.001) only; log TQ scores were not significantly related to levels of comfort when viewing control images of holes (r = − 0.2, p = 0.24). We also ran an additional analysis and removed the six individuals who scored in the trypophobic range (above 31). The results did not change: Log TQ scores significantly predicted lower comfort levels when viewing trypophobic images (r = − 0.45, p = 0.015) only; log TQ scores were not significantly related to levels of comfort when viewing control images of holes (r = −0.09, p = 0.66).
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R. Nathan Pipitone et al. / Personality and Individual Differences 108 (2017) 66–68
To address discriminant validity, the relationship between TQ scores and measures of generalized anxiety as measured by the GAD-7 was also assessed (GAD-7 M = 5.91, SD = 5.18). Scores on the TQ were not significantly correlated with GAD-7 scores (r = 0.14, p = 0.44), replicating findings from Le et al. (2015), although their study utilized the STAI to measure levels of anxiety. 3.2. Physiological activity As participants viewed trypophobic and control images, mean and max levels of EDA and BPM were assessed. When viewing trypophobic images, participants had higher EDA mean responses (M = 0.0078, SD = 0.037) compared to viewing control images (M = − 0.015, SD = 0.036), t(33) = 2.12, p = 0.041, d = 0.36. Similar results were found for EDA max responses: Higher peaks in EDA were found when viewing trypophobic images (M = 0.22, SD = 0.23) compared to control images (M = 0.19, SD = 0.19), t(33) = 2.39, p = 0.023, d = 0.41. However, participant BPM was not significantly different when viewing trypophobic versus control images t(32) = − 1.63, p = 0.114, d = − 0.28. We then assessed whether between-subject variation in physiological responses could predict scores on the TQ, just like subjective levels of comfort could. Results showed that participants' overall physiological responses (using mean and max trypophobic responses minus their responses in the respective control condition) did not correlate with their scores on the TQ: EDA Mean (r = − 0.016, p = 0.93); EDA Max (r = −0.072, p = 0.7); BPM (r = −0.246, p = 0.17). Lastly, although lower levels of comfort when viewing trypophobic images related to increases in EDA mean (r = − 0.259, p = 0.14), EDA max (r = −0.217, p = 0.22) levels, and decreases in BPM (r = 0.138, p = 0.4) when viewing trypophobic vs. control images, the relationships were not significant. 4. Discussion The present study replicates findings from previous work that shows participants from a non-clinical population react negatively to trypophobic imagery compared to control images (Cole & Wilkins, 2013; Le et al., 2015). We also replicate Le et al. (2015) which showed convergent and discriminant validity for the Trypophobia Questionnaire (TQ): Lower levels of comfort when viewing trypophobic imagery were significantly associated with higher scores on the TQ, but participants' TQ scores were unrelated to measures of generalized anxiety. In other words, although participants report negative reactions when viewing trypophobic imagery in general, it is not a function of having higher levels of generalized anxiety. We then document heightened physiological responses, as measured by mean and max EDA levels, when viewing trypophobic images compared to control images. Heart rate (BPM) among participants viewing trypophobic and control images did not reveal significant differences. Although both EDA and heart rate have been shown to accurately detect concealed information, EDA provides the most accurate physiological responses (Gamer, Verschuere, Crombez, & Vossel, 2008). Thus, we suspect that BPM was not able to elucidate meaningful differences between participants, especially considering the shorter timeframe of our stimulus presentation/recording regimen. Although overall EDA measures were higher in participants when viewing trypophobic imagery, between-subject variation in physiological responses did not correlate with scores on the TQ. In other words, subjective assessments of discomfort towards trypophobic imagery seem to be a better predictor of scores on the TQ than participants' physiological responses, at least in the present study. Our original impetus was to investigate whether overall physiological differences could be
detected when participants viewed trypophobic vs. control images, and to further assess convergent and discriminant validity of the TQ with subjective measures. Our sample sizes were not sufficient in order to assess meaningful relationships between participant physiology and TQ scores, or with subjective ratings of comfort. While this may be a sign of poor convergent validity for the TQ, future work will hopefully shed light on whether validity can be detected in this way. The present study supports the interpretation originally put forth by Cole and Wilkins (2013) that in general, negative reactions are seen among participants that view trypophobic imagery. As Cole and Wilkins (2013) show, these images share similar spatial frequency profiles with dangerous animals. While full-blown trypophobia is fairly uncommon, our findings indicate that non-clinical populations show heightened physiological responses when viewing such images. Increases in physiological responses such as EDA reflect heightened sympathetic nervous system arousal from changes in emotion and attention (e.g., Critchley, Elliott, Mathias, & Dolan, 2000). While most images depicting trypophobic clusters are not dangerous, they accompany similar spectral profiles of animals that are, suggesting a primitive threat detection system might be triggered when viewing both image types. Indeed, Van Strien and Van der Peijl (2015) have recently shown that trypophobic and snake images elicit heightened early posterior negativity in occipital and parieto-occipital cortical areas, suggesting that these images hold phylogenetic importance. 5. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Acknowledgements The authors would like to thank Arnold Wilkins and An Le for providing stimuli used in previous work and the TQ questionnaire. References Bradley, M. M., & Lang, P. J. (2007). The international affective picture system (IAPS) in the study of emotion and attention. In J. A. Coan, & J. B. Allen (Eds.), Handbook of emotion elicitation and assessment (pp. 29–46). New York, N.Y: Oxford University Press. Braithwaite, J. J., Watson, D. G., Jones, R. & Rowe, M. (2013). A guide for analysing electrodermal activity (EDA) & skin conductance responses (SCRs) for psychological experiments, pg. 1–42. (Retrieved from:) http://www.biopac.com/wp-content/uploads/ EDA-SCR-Analysis.pdf Cole, G. G., & Wilkins, A. J. (2013). Fear of holes. Psychological Science, 24(10), 1980–1985. Critchley, H. D., Elliott, R., Mathias, C. J., & Dolan, R. J. (2000). Neural activity relating to generation and representation of galvanic skin conductance responses: A functional magnetic resonance imaging study. The Journal of Neuroscience, 20(8), 3033–3040. Fernandez, D., & Wilkins, A. J. (2008). Uncomfortable images in art and nature. Perception, 37, 1098–1113. Gamer, M., Verschuere, B., Crombez, G., & Vossel, G. (2008). Combining physiological measures in the detection of concealed information. Physiology & Behavior, 95, 333–340. Le, A. T. D., Cole, G. G., & Wilkins, A. J. (2015). Assessment of trypophobia and an analysis of its visual precipitation. The Quarterly Journal of Experimental Psychology, 68(11), 2304–2322. Levenson, R. W., Ekman, P., & Friesen, W. V. (1990). Voluntary facial action generates emotion-specific autonomic nervous system activity. Psychophysiology, 27(4), 22. Shoup-Knox, M. L., & Pipitone, R. N. (2015). Physiological changes in response to hearing female voices recorded at high and low fertility. Physiology & Behavior, 139, 386–392. Spitzer, R. L., Kroenke, K., Williams, J. B. W., & Lowe, B. (2006). A brief measure for assessing generalized anxiety disorder. Archives of Internal Medicine, 166, 1092–1097. Van Strien, J. W., & Van der Peijl, M. K. (2015). Enhanced early posterior negativity in response to trypophobic stimuli. 55th annual meeting of the society for psychophysiological research.
Contents lists available at ScienceDirect
Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid
Short Communication
Physiological responses to trypophobic images and further scale validity of the trypophobia questionnaire R. Nathan Pipitone ⁎, Brandon Gallegos, Danielle Walters Adams State University, Alamosa, CO 81101, USA
a r t i c l e
i n f o
Article history: Received 16 September 2016 Received in revised form 29 November 2016 Accepted 30 November 2016 Available online xxxx Keywords: Anxiety Fear Human physiology Trypophobia
a b s t r a c t Trypophobia, or the fear of small clusters of objects in close proximity to one another is a unique and recently discovered phenomenon to the scientific literature. Recent work has shown that a small subset of the human population will react adversely to trypophobic images. Although trypophobia at first glance seems irrational, these images might be triggering a primitive threat detection system that has adaptive functionality - trypophobic images share similar spectral characteristics also found among dangerous animals. In the present study, we replicate previous work showing increased levels of discomfort when viewing trypophobic images and also provide further validation for a newly designed questionnaire that measures participants' level of trypophobia. Measuring participant physiology, we then show an increase in two measures of electrodermal activity when participants viewed trypophobic images compared to control images. Our results add to the accumulating literature investigating the adaptive rationale for exhibiting heightened fear responses when viewing trypophobic imagery. © 2016 Elsevier Ltd. All rights reserved.
1. Introduction Trypophobia, or the fear of small clusters of objects in close proximity to each other (commonly elicited from small clusters of holes) is a unique and recently documented phenomenon in the scientific literature (Cole & Wilkins, 2013; Le, Cole, & Wilkins, 2015). Recent work has shown that on average, adults rate trypophobic images as being more uncomfortable to view compared to control images (images that usually depict one large hole), with a small portion (15%) of their sample finding trypophobic images particularly repulsive to view (see Fig. 1 for a trypophobic image example). Cole and Wilkins (2013) also assessed the spectral frequencies of trypophobic images and found them to exhibit high-contrast energy at midrange spatial frequencies. The excess energy at midrange spatial frequencies is also present among images that depict poisonous animals such as the poison dart frog, puffer fish, snakes, spiders (Cole & Wilkins, 2013), and other images found in nature that are generally uncomfortable to view (Fernandez & Wilkins, 2008). While at first glance it may seem irrational to exhibit an adverse reaction to patterns of small clustered objects, these images might be triggering a primitive threat detection system that has adaptive functionality when put into the context of images ⁎ Corresponding author at: Adams State University, Department of Psychology, 208 Edgemont Boulevard, Alamosa, CO 81101, United States. E-mail address: [email protected] (R. Nathan Pipitone).
http://dx.doi.org/10.1016/j.paid.2016.11.068 0191-8869/© 2016 Elsevier Ltd. All rights reserved.
that usually encompass these characteristic visual patterns in the natural world. In the present study, we attempt to replicate work using the exact same stimuli used in Cole and Wilkins (2013), which showed levels of comfort changing as a consequence of viewing trypophobic images. We also incorporate a recently designed Trypophobia Questionnaire (TQ) developed by Le et al. (2015) to assess whether levels of comfort when viewing trypophobic and control images relate to scores on the TQ (i.e., convergent validity). We then investigate discriminant validity of the TQ by collecting participants' level of generalized anxiety to see if TQ scores are independent of generalized anxiety levels. Finally, we assess participants' physiological responses using measures of electrodermal activity (EDA) and heart rate (BPM) when viewing trypophobic and control images. Using physiological measures in conjunction with subjective reports provides a better depiction of participants' emotional state (Bradley & Lang, 2007) and can also provide basic, automatic, and possibly lower-level conscious emotional processing, especially when dealing with evolutionarily threat-relevant stimuli (Shoup-Knox & Pipitone, 2015). Based on previous work which showed lower levels of comfort when viewing trypophobic images and the images sharing similar spatial frequency profiles as dangerous animals, we hypothesize that viewing trypophobic images will elicit a heightened EDA response and changes in BPM compared to control images (BPM has been shown to accelerate during negative emotional states [e.g., Levenson, Ekman, & Friesen, 1990] but also decelerate during unpleasant stimuli processing
R. Nathan Pipitone et al. / Personality and Individual Differences 108 (2017) 66–68
Fig. 1. The Lotus seed head is a well-known trigger for trypophobic individuals. Photograph retrieved from https://commons.wikimedia.org/wiki/File:LOTUS_SEEDPOD. JPG, Author: 3Point141.
[e.g., Bradley & Lang, 2007]). We also assess whether higher physiological responses to trypophobic images exist among participants who score higher on levels of trypophobia, based on the TQ.
67
presentation displayed an array of 50 trypophobic and 50 control images, which alternated during the course of the experiment. These images were the same images from Cole and Wilkins (2013), and contained a variety of living and non-living trypophobic and control pictures. When the participants were ready, a picture of a plain grassy field was shown for 1 min to establish a baseline for all physiological measures. After the baseline session, the slideshow then automatically moved through the images every 12 s, with 7 s of stimulus presentation and a 5-s blank screen in order for participant physiology to return to baseline and so they could rate their level of comfort for each image. During the physiological recording session, participants were asked to provide levels of comfort for each image on a scale from −5 (extremely uncomfortable) to 5 (extremely comfortable) via a self-report survey. Physiological measures were recorded using Biopac Student Lab (BSL) PRO 3.7.7 software. After the data were collected, the signals from the physiological measures were adjusted to reduce noise, drift, and in the case of ECG converted to BPM for heartrate. A 10 Hz high pass filter was applied to the ECG signal. A 0.03 Hz high pass filter was applied to the EDA signal to reduce the effects of tonic drift and to focus on the phasic EDA responses (Braithwaite, Watson, Jones, & Rowe, 2013). We then used BSL PRO 4.0.1 software to select appropriate response time intervals (seconds 1–6) to measure differences in EDA and BPM responses during stimulus presentation. The overall mean and max measures of EDA as well as mean BPM for selected intervals were exported to excel spreadsheets and then transferred to IBM SPSS 23 where statistical analyses could be conducted.
2. Method 3. Results 2.1. Participants Thirty-seven undergraduate students from a university in Southern Colorado were recruited to participate in the present study (16 male, 21 female; mean age = 22.59, SD = 7.96). The study was approved by the University IRB. Participants volunteered to be in the study in exchange for extra credit in their classes. Participants were asked to fill out a demographic questionnaire which contained information about past history of psychological disorders, phobias, anxiety, and any prescribed medication. One participant was excluded because of medical issues, incomplete comfort ratings, and also for abnormal physiological responses during the biofeedback session. Three participants' EDA scores and four participants' BPM scores were removed from analyses because of incomplete responses during the physiological recording sessions. 2.2. Procedure and materials The TQ was administered first, which involved participants looking at two characteristic trypophobic images (an image of a lotus seedpod and a close-up of a honeycomb) and asked to provide responses to 17 questions that surround negative emotional reactions to the images (e.g., feel nervous, feel panicky, feel skin crawl) on a 5-point Likert scale (ranging from not at all to extremely). The TQ has been shown to be a reliable measure of trypophobia (Cronbach's alpha = 0.96), with construct, convergent and discriminant validity being established (Le et al., 2015). Participants then filled out the GAD-7, a seven-item questionnaire that assesses levels of generalized anxiety (Spitzer, Kroenke, Williams, & Lowe, 2006). After the completion of the survey materials, participants had Biopac SS2L and SS57L electrodes attached to the index and middle fingers on their non-dominant hand, wrist, and both ankles with a small application of Signa gel added to foam disposable EL 503 electrodes in order to collect electrodermal activity (EDA) and electrocardiogram (ECG) data. Prior to placement of the electrodes, alcohol swabs were used to clean the skin surface. ECG data was converted into beats per minute (BPM), and EDA was measured in microsiemens (μS) for analysis. Participants then sat in front of a computer monitor where a PowerPoint
Heart rate at the baseline measure fell within a normal range of 49.13–103.72 BPM (M = 77.12, SD = 12.4). Unfiltered electrodermal activity (EDA) at baseline ranged from 1.01 to 42.38 μS (M = 14.7, SD = 9.17). Scores on the TQ indicated that 6 out of 35 participants (17%) of our sample scored above the threshold (scores above 31) for trypophobia (Le et al., 2015). The percentage of individuals with trypophobia is comparable to what Cole and Wilkins (2013) found in their sample. The TQ showed good reliability after removing the two foil items (Cronbach's alpha = 0.887). 3.1. Validity assessment We first sought to replicate previous work (Cole & Wilkins, 2013) that showed lower levels of comfort when viewing trypophobic images. Overall, participants reported lower levels of comfort when viewing trypophobic images (M = 0.99, SD = 2.04) compared to control images of holes (M = 2.48, SD = 1.55), t(35) = −5.95, p b 0.001, d = 0.99. To explore convergent validity, a Pearson correlation was conducted between TQ scores and participants' comfort level when viewing trypophobic and control images. Results showed that higher TQ scores correlated significantly with lower comfort levels when viewing trypophobic images (r = − 0.57, p b 0.001) only; TQ scores were not significantly related to levels of comfort when viewing control images of holes (r = − 0.202, p = 0.2), replicating findings from Le et al. (2015). Our sample included several participants who scored higher on the TQ, which skewed the variable somewhat. Because of this, we log transformed the variable and ran the correlations again. Results showed the same trends: Log TQ scores correlated significantly with lower comfort levels when viewing trypophobic images (r = − 0.61, p b 0.001) only; log TQ scores were not significantly related to levels of comfort when viewing control images of holes (r = − 0.2, p = 0.24). We also ran an additional analysis and removed the six individuals who scored in the trypophobic range (above 31). The results did not change: Log TQ scores significantly predicted lower comfort levels when viewing trypophobic images (r = − 0.45, p = 0.015) only; log TQ scores were not significantly related to levels of comfort when viewing control images of holes (r = −0.09, p = 0.66).
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R. Nathan Pipitone et al. / Personality and Individual Differences 108 (2017) 66–68
To address discriminant validity, the relationship between TQ scores and measures of generalized anxiety as measured by the GAD-7 was also assessed (GAD-7 M = 5.91, SD = 5.18). Scores on the TQ were not significantly correlated with GAD-7 scores (r = 0.14, p = 0.44), replicating findings from Le et al. (2015), although their study utilized the STAI to measure levels of anxiety. 3.2. Physiological activity As participants viewed trypophobic and control images, mean and max levels of EDA and BPM were assessed. When viewing trypophobic images, participants had higher EDA mean responses (M = 0.0078, SD = 0.037) compared to viewing control images (M = − 0.015, SD = 0.036), t(33) = 2.12, p = 0.041, d = 0.36. Similar results were found for EDA max responses: Higher peaks in EDA were found when viewing trypophobic images (M = 0.22, SD = 0.23) compared to control images (M = 0.19, SD = 0.19), t(33) = 2.39, p = 0.023, d = 0.41. However, participant BPM was not significantly different when viewing trypophobic versus control images t(32) = − 1.63, p = 0.114, d = − 0.28. We then assessed whether between-subject variation in physiological responses could predict scores on the TQ, just like subjective levels of comfort could. Results showed that participants' overall physiological responses (using mean and max trypophobic responses minus their responses in the respective control condition) did not correlate with their scores on the TQ: EDA Mean (r = − 0.016, p = 0.93); EDA Max (r = −0.072, p = 0.7); BPM (r = −0.246, p = 0.17). Lastly, although lower levels of comfort when viewing trypophobic images related to increases in EDA mean (r = − 0.259, p = 0.14), EDA max (r = −0.217, p = 0.22) levels, and decreases in BPM (r = 0.138, p = 0.4) when viewing trypophobic vs. control images, the relationships were not significant. 4. Discussion The present study replicates findings from previous work that shows participants from a non-clinical population react negatively to trypophobic imagery compared to control images (Cole & Wilkins, 2013; Le et al., 2015). We also replicate Le et al. (2015) which showed convergent and discriminant validity for the Trypophobia Questionnaire (TQ): Lower levels of comfort when viewing trypophobic imagery were significantly associated with higher scores on the TQ, but participants' TQ scores were unrelated to measures of generalized anxiety. In other words, although participants report negative reactions when viewing trypophobic imagery in general, it is not a function of having higher levels of generalized anxiety. We then document heightened physiological responses, as measured by mean and max EDA levels, when viewing trypophobic images compared to control images. Heart rate (BPM) among participants viewing trypophobic and control images did not reveal significant differences. Although both EDA and heart rate have been shown to accurately detect concealed information, EDA provides the most accurate physiological responses (Gamer, Verschuere, Crombez, & Vossel, 2008). Thus, we suspect that BPM was not able to elucidate meaningful differences between participants, especially considering the shorter timeframe of our stimulus presentation/recording regimen. Although overall EDA measures were higher in participants when viewing trypophobic imagery, between-subject variation in physiological responses did not correlate with scores on the TQ. In other words, subjective assessments of discomfort towards trypophobic imagery seem to be a better predictor of scores on the TQ than participants' physiological responses, at least in the present study. Our original impetus was to investigate whether overall physiological differences could be
detected when participants viewed trypophobic vs. control images, and to further assess convergent and discriminant validity of the TQ with subjective measures. Our sample sizes were not sufficient in order to assess meaningful relationships between participant physiology and TQ scores, or with subjective ratings of comfort. While this may be a sign of poor convergent validity for the TQ, future work will hopefully shed light on whether validity can be detected in this way. The present study supports the interpretation originally put forth by Cole and Wilkins (2013) that in general, negative reactions are seen among participants that view trypophobic imagery. As Cole and Wilkins (2013) show, these images share similar spatial frequency profiles with dangerous animals. While full-blown trypophobia is fairly uncommon, our findings indicate that non-clinical populations show heightened physiological responses when viewing such images. Increases in physiological responses such as EDA reflect heightened sympathetic nervous system arousal from changes in emotion and attention (e.g., Critchley, Elliott, Mathias, & Dolan, 2000). While most images depicting trypophobic clusters are not dangerous, they accompany similar spectral profiles of animals that are, suggesting a primitive threat detection system might be triggered when viewing both image types. Indeed, Van Strien and Van der Peijl (2015) have recently shown that trypophobic and snake images elicit heightened early posterior negativity in occipital and parieto-occipital cortical areas, suggesting that these images hold phylogenetic importance. 5. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Acknowledgements The authors would like to thank Arnold Wilkins and An Le for providing stimuli used in previous work and the TQ questionnaire. References Bradley, M. M., & Lang, P. J. (2007). The international affective picture system (IAPS) in the study of emotion and attention. In J. A. Coan, & J. B. Allen (Eds.), Handbook of emotion elicitation and assessment (pp. 29–46). New York, N.Y: Oxford University Press. Braithwaite, J. J., Watson, D. G., Jones, R. & Rowe, M. (2013). A guide for analysing electrodermal activity (EDA) & skin conductance responses (SCRs) for psychological experiments, pg. 1–42. (Retrieved from:) http://www.biopac.com/wp-content/uploads/ EDA-SCR-Analysis.pdf Cole, G. G., & Wilkins, A. J. (2013). Fear of holes. Psychological Science, 24(10), 1980–1985. Critchley, H. D., Elliott, R., Mathias, C. J., & Dolan, R. J. (2000). Neural activity relating to generation and representation of galvanic skin conductance responses: A functional magnetic resonance imaging study. The Journal of Neuroscience, 20(8), 3033–3040. Fernandez, D., & Wilkins, A. J. (2008). Uncomfortable images in art and nature. Perception, 37, 1098–1113. Gamer, M., Verschuere, B., Crombez, G., & Vossel, G. (2008). Combining physiological measures in the detection of concealed information. Physiology & Behavior, 95, 333–340. Le, A. T. D., Cole, G. G., & Wilkins, A. J. (2015). Assessment of trypophobia and an analysis of its visual precipitation. The Quarterly Journal of Experimental Psychology, 68(11), 2304–2322. Levenson, R. W., Ekman, P., & Friesen, W. V. (1990). Voluntary facial action generates emotion-specific autonomic nervous system activity. Psychophysiology, 27(4), 22. Shoup-Knox, M. L., & Pipitone, R. N. (2015). Physiological changes in response to hearing female voices recorded at high and low fertility. Physiology & Behavior, 139, 386–392. Spitzer, R. L., Kroenke, K., Williams, J. B. W., & Lowe, B. (2006). A brief measure for assessing generalized anxiety disorder. Archives of Internal Medicine, 166, 1092–1097. Van Strien, J. W., & Van der Peijl, M. K. (2015). Enhanced early posterior negativity in response to trypophobic stimuli. 55th annual meeting of the society for psychophysiological research.