The fashion assumption that vertical stripes create the slimmest silhouette has been overturned. Stripe spacing interacts with orientation to determine how a clothed body appears, and narrow horizontal pencil stripes have been found to produce the strongest slimming effect. The result varies by viewing angle, with vertical stripes proving more slimming from behind, and women have been found more responsive than men to these pattern effects.
- Horizontal pencil stripes with a two-centimetre white gap produced the strongest slimming effect, with more than half of the 241 participants selecting this pattern.
- Vertical equidistant stripes outperformed horizontal patterns for slimming perception when the body was viewed from behind, showing how viewing direction fundamentally alters visual judgement.
- Women were found to be more sensitive than men to the visual effects of stripe patterns when evaluating body image and perceived appearance.
- The findings have been revealed in 'The influence of striped clothing on visual body perception: A study on pattern spacing design', published in i-Perception.
INSIDE THE EXPERIMENT: To examine how stripe spacing and orientation interact to shape body perception, researchers built on the Helmholtz illusion—the principle that horizontal lines can make a space or figure appear taller and narrower than vertical lines do—designing a controlled visual experiment using a female model photographed in a slim-fitting dress across five stripe configurations. Participants assessed images on screen, rating each pattern's effect on the model's perceived body shape.
- The study was conducted by Tzu-Yu Chen, a PhD candidate, and Li-Hsun Peng, a retired associate professor, both at the Graduate School of Design at National Yunlin University of Science and Technology.
- The experiment recruited 241 undergraduate students from a university in Taiwan to evaluate stripe patterns through a structured visual survey.
- Two pattern categories were tested: equidistant stripes, where line and gap width are equal, and pencil stripes, where the light background spaces are significantly wider than the dark lines.
- Five stripe measurements were used, spanning one, two, and five centimetres in equidistant configurations and two pencil stripe variants with differing gap widths.
- The third experiment showed horizontal and vertical versions of the same dress on alternating screens, requiring participants to rely on short-term memory to simulate real-world observation conditions.
- The model photographed for the study had a Body Mass Index of 20.8, representing an average to slightly above-average body type for Taiwanese women.
- People often purchase striped clothing to enhance their body image—the subjective mental picture of one's own physical appearance—making optical illusions a practically significant area of fashion design research.
PATTERNS AND PERCEPTION: Across three experiments, the results revealed that stripe spacing shapes slimming perception as decisively as orientation. Narrow horizontal pencil stripes consistently outperformed vertical configurations, while vertical stripes yielded inconsistent results overall. The third experiment, which directly compared both orientations, showed vertical stripes performing better from behind. Limitations include a single model prototype and a participant group drawn from the same demographic, which may affect applicability across age groups.
- The 1×2 pencil stripe configuration earned the highest slimming rating in the first experiment, with support from more than half of all participants surveyed.
- Horizontal stripes with a five-centimetre white gap received the least support for a slimming effect, indicating that wider spacing undermines the pencil stripe's slimming potential.
- The second experiment, testing vertical stripes exclusively, produced no consensus among participants, with responses varying significantly across all configurations tested.
- In the direct comparison experiment, vertical equidistant stripes were perceived as more slimming from behind, and the 1×1 configuration may be a more effective option for those with a fuller figure.
- The 2×2 horizontal stripe has been identified as a functional maternity wear option; one researcher also noted wearing the pattern personally during pregnancy.
- The 2×2 pattern held its perceptual effect stable across eight body types; future research may test these findings on looser clothing, varied fabric types, and wider colour ranges.
WHAT THEY SAID
In the field of design psychology, I wanted to move beyond the traditional binary of 'horizontal vs. vertical stripes.' […] Most existing studies focus solely on orientation, but our research demonstrates that the interaction between stripe type and stripe orientation significantly influences visual body perception. Interestingly, our study also revealed that women tend to be more sensitive to these striped patterns than men when evaluating body image.
— Li-Hsun Peng
Retired Associate Professor
National Yunlin University of Science and Technology
