An exploration of trypophobia

Images comprising clusters of objects can induce aversion and certain symptoms of anxiety, fear and disgust (so-called “trypophobia”) in about 13% of the population. This thesis is an investigation of the stimulus and response characteristics of the condition. First, a symptom questionnaire (Trypophobia Questionnaire) was developed and validated based on reports of different categories of symptoms. The questionnaire demonstrated a single construct that predicted discomfort from trypophobic images, but not neutral or unpleasant images, and did not correlate with anxiety. Second, filtering images reduced the excess energy at mid-range spatial frequencies (previously associated with both trypophobic and uncomfortable images). Relative to unfiltered trypophobic images, the discomfort from filtered images experienced by observers with high TQ scores was less than that experienced with neutral images, and by observers with low TQ scores. Clusters of concave objects (holes) did not induce significantly more discomfort than clusters of convex objects (bumps), suggesting that trypophobia (previously referred to as “fear of holes”) involves clusters not of holes but of objects with particular spectral profile involving excess energy at mid-range spatial frequencies. These visual characteristics have been previously shown to induce discomfort and a strong cortical oxygenation. The same abnormal oxygenation occurred for trypophobic images, but only for individuals with high TQ scores. Three lines of evidence suggest that trypophobia is a response of disgust rather than fear: (1) trypophobia was associated with an aversion to spiders, and not snakes; (2) trypophobic stimuli did not produce a bias in the subjective estimation of stimulus duration but (3) increased the heart rate and its variability. Fear inducing stimuli generally give effects opposite to those listed as 2 and 3. In conclusion, trypophobia is a reaction of disgust to clusters of objects with particular spectral profile that may resemble contamination sources (e.g., skin lesions).