Trypophobia—an aversion to visual patterns of grouped objects, such as holes or protrusions—has gained increasing attention in the neuroscience of perception. Originally associated with the presence of excessive spectral energy at mid-spatial frequencies, recent evidence challenges this reductionist view. The study conducted by Pipitone and DiMattina (2020) presents a rigorous experiment, based on Fourier analysis, to dissociate and evaluate the relative contribution of phase and amplitude spectra in trypophobic images in the genesis of visual discomfort.
The spectral amplitude of an image determines which spatial frequencies are present (i.e., the energy distribution of the image), while the phase spectrum regulates the spatial arrangement of these frequencies, being responsible for the formation of contours and patterns (e.g., the circular clusters characteristic of trypophobia). Using independent manipulations of these two parameters, the authors applied a full factorial approach to 31 trypophobic images, creating four conditions: original image, original phase with natural amplitude (1/f), original amplitude with scrambled phase, and full 1/f noise.
The findings are striking: phase spectrum had a significantly greater impact on participants’ reported discomfort levels, explaining 24.9% of the variance in comfort ratings, versus only 9% attributed to amplitude spectrum. Furthermore, the interaction between phase and amplitude accounted for only 6.1% of the variance. Participants with high scores on the Trypophobia Questionnaire (TQ) reported significantly more discomfort only when the original phase spectrum was present, regardless of amplitude—reinforcing the notion that visual clustering (rather than spectral power distribution) is the primary determinant of trypophobic discomfort.
It is worth noting that a control analysis was conducted to rule out the potential effect of mere phase randomization as a cause of comfort. Interestingly, in neutral (non-trypophobic) images, phase scrambling reduced visual comfort—further evidence that, in the trypophobic context, discomfort arises from the preservation of spatial structure, not from general image distortions.
This finding has direct implications for evolutionary hypotheses about the genesis of trypophobia. Contrary to the theory that associates the aversion response to the detection of predators with specific spectral patterns (such as snakes or poisonous insects), the data favor the “disease avoidance” hypothesis. The spectral phase gives the images the appearance of skin lesions or parasitic infestations—stimuli that, adaptively, could evoke disgust responses and avoid contact with potential sources of contagion. Supporting this line of thought, individuals with a history of dermatological diseases showed higher levels of discomfort when viewing such images in previous studies.
Although spectral amplitude (particularly at mid-frequencies) has been identified by previous studies as a contributing factor to visual discomfort in general — probably by overloading neurons in the primary visual area (V1), as proposed by the cortical hypermetabolism hypothesis — in the specific case of trypophobia, the impact of this component appears to be secondary, acting only to intensify the salience of the patterns defined by the phase.
A relevant limitation, acknowledged by the authors themselves, is that the manipulation of the phase spectrum was still limited to complete randomization. Future investigations could systematically test different forms of spatial organization, including semantic variations (e.g., non-circular groupings), to deepen the understanding of the specific triggers of trypophobia.
In summary, the work of Pipitone and DiMattina (2020) reformulates the debate on the perceptual mechanisms of trypophobia, shifting the focus from spectral energy to the structural organization of images. This paradigm shift emphasizes the importance of visual semantic content—not just low-level statistics—in the affective processing of visual information.
Reference:
PIPITONE, RN; DIMATTINA, C. Object Clusters or Spectral Energy? Assessing the Relative Contributions of Image Phase and Amplitude Spectra to Trypophobia. Frontiers in Psychology, v. 11, p. 1847, 2020. Available at: https://doi.org/10.3389/fpsyg.2020.01847. Accessed on: June 17, 2025.
