The research rests on a well-established phenomenon in cognitive neuroscience known as a body illusion. In classic experiments, scientists have shown that the brain’s representation of the body is remarkably plastic. If people hear sounds whose frequency changes in ways that would be consistent with, say, their fingers being longer or shorter than they actually are, their estimates of their own body dimensions shift accordingly. These effects, sometimes called auditory-driven body transformation illusions, demonstrate that the brain integrates sounds with proprioceptive and tactile signals to build a live model of the body. Crucially, previous work has hinted that people with clinical and subclinical eating disorders integrate this multisensory bodily information atypically, which could contribute to the development and maintenance of body image disturbance.

What remained unclear, and what motivated the new study, was whether these impairments are specific to sounds that carry information about the body itself, or whether they extend to auditory cues more generally. A second open question concerned emotional salience. Body image disturbance in eating disorders is not distributed evenly across the body. Regions such as the waist and abdomen carry intense emotional and attitudinal weight for many people with disordered eating, whereas a fingertip is largely neutral. If multisensory updating of the body model is disrupted mainly for emotionally charged regions, that would point to an interaction between perceptual and attitudinal factors in shaping body image, rather than a general sensory deficit.

To address these questions, the researchers recruited 87 participants and allocated them to either a subclinical eating disorder group or a control group based on their scores on the Eating Disorder Examination Questionnaire, a widely used self-report measure of eating disorder psychopathology. The design then split into two experiments. The first tested a finger length illusion, in which sounds were used to alter participants’ estimates of the length of their own fingertip. The second tested a waist size illusion, in which auditory feedback was manipulated to change how large or small participants perceived their waist to be. In both experiments, illusion strength was captured in two ways: through explicit measures, meaning direct estimates of finger length or waist size, and through self-report questionnaires probing the subjective experience of the illusion.

The results revealed a striking task-specific pattern. Consistent with prior findings, sound had an overall effect on fingertip position and on the finger length estimates derived from it. Participants across the board experienced the auditory manipulation of their finger in broadly the same way. When the researchers compared the subclinical eating disorder group with the control group on this task, however, the effect of sound on finger estimates did not differ significantly between the two groups. In other words, when the body region in question was emotionally neutral, the basic machinery of auditory-driven body updating appeared to be intact in people with elevated eating disorder symptoms.

The waist experiment told a different story. Here, the control group showed the expected effect: sounds reliably produced a waist-shrinking illusion, with participants perceiving their waist as smaller in response to the auditory manipulation. The subclinical eating disorder group, by contrast, did not show this waist-shrinking effect in response to sound. The difference between the groups was statistically detectable in the control condition but absent among participants with higher eating disorder symptomatology. This dissociation, intact finger illusion but reduced waist illusion, is the study’s central finding, and it raises the possibility that sound-based changes in body perception are specifically reduced for emotionally salient body regions in individuals with elevated eating disorder symptoms.

The authors are careful about interpretation, and for good reason. Because the two experiments were not designed as a direct statistical comparison of body parts within the same analysis, the task-specific pattern should be confirmed in studies that directly compare body-part differences. Still, the pattern fits a broader theoretical picture in which body image is built from two interacting layers. The first is perceptual: the continuously updated multisensory representation of body size and shape, which can be nudged by illusions of many kinds. The second is attitudinal: the beliefs, emotions and evaluations a person attaches to particular body regions. The new findings suggest that attitudinal factors contribute to body image distortions alongside perceptual factors, particularly for emotionally salient body regions such as the waist. In people with elevated eating disorder symptomatology, strong attitudinal weight on the waist may dampen or override the perceptual updating that sounds would otherwise produce.

Beyond the finger and waist tasks, the study also examined individual differences in interoceptive awareness, the sense of the body’s internal states, and in sensory-processing sensitivity, a trait describing how strongly people respond to sensory stimuli. These secondary measures reflect the team’s interest in how broader individual differences in bodily and sensory processing might modulate the illusions. Prior research has linked altered interoception to eating disorders, making such measures a natural complement to the main experimental manipulation, although the abstract positions these analyses as secondary aims rather than the headline result.

The methodological significance of the waist illusion deserves emphasis. If sounds can reliably and temporarily alter perceived waist size in healthy participants, the illusion becomes a laboratory tool for probing how the body model responds to perturbation, and for measuring where that responsiveness breaks down. The fact that the effect was absent in the subclinical eating disorder group suggests the illusion could serve as a sensitive marker of atypical body representation, potentially useful for assessment before symptoms reach clinical thresholds. The authors suggest that future studies should further validate the waist illusion as a tool to target body image disturbances and explore its potential as a complementary component in cognitive-behavioural interventions, the leading evidence-based psychological treatment for eating disorders. A sensory-level intervention that loosens rigid body representations could, in principle, complement the cognitive work of challenging distorted beliefs about shape and weight.

Several caveats frame the contribution. The study used a subclinical sample defined by questionnaire scores rather than clinical diagnoses, so the findings speak most directly to people with elevated symptomatology rather than diagnosed patients. The interpretation of the waist result as an emotionally salience effect, while plausible and theoretically grounded, awaits confirmation through direct body-part comparisons. And the sounds used were non-naturalistic, meaning they were synthetic auditory cues rather than the natural sounds of body movement, which leaves open questions about how everyday auditory feedback behaves in this population. Even so, the study marks a meaningful step. It shows that the ears reach all the way to the waist, that this auditory pathway into body perception can be measured experimentally, and that in people with eating disorder symptoms the pathway appears to falter precisely where body image disturbance bites hardest. As the authors and their funders, including the Spanish Agencia Estatal de Investigación and the European Research Council, continue this line of work under projects such as MAGIC outFIT and SENSEBEAT-DS, sound-based body illusions may move from the laboratory bench toward the clinic, offering a new way to see, and perhaps to soften, the distorted body from the inside out.

Subject of Research: Auditory-driven body perception illusions in relation to eating disorder symptomatology

Article Title: From ears to waist: the influence of non-naturalistic sounds on body perception in relation to eating disorders symptomatology

Article References: Navas-León, S., Tajadura-Jiménez, A., Sánchez-Martín, M., Crucianelli, L., & Morales, L. (2026). From ears to waist: the influence of non-naturalistic sounds on body perception in relation to eating disorders symptomatology. Journal of Eating Disorders. https://doi.org/10.1186/s40337-026-01747-y

Image Credits: AI Generated

DOI: 10.1186/s40337-026-01747-y

Keywords: eating disorders, body image, auditory feedback, body illusions, multisensory integration, body perception, waist size illusion, finger length illusion, interoception, cognitive-behavioural interventions, size perception, sensory processing