The Barber-Pole illusion and the peripheral motion processing of line-ends
Bibliographic record
Abstract
In the Barber-Pole illusion (BPI), a drifting 1D texture is viewed through an elongated aperture and the perceived direction of motion is generally along the orientation of the aperture rather than the Fourier component (i.e., orthogonal to the 1D texture). According to the motion-path-integration theory, the BPI results from a greater path-motion energy along the aperture’s elongated orientation. Alternatively, the end-stop theory rather suggests that the perceived direction of motion is driven by the processing of line-ends along the contours of the aperture. Although there is good evidence supporting the end-stop theory for foveal viewing, its applicability for peripheral viewing (>10 degrees) has been questioned. The current study investigated the underlying cause of the BPI under peripheral viewing conditions (20 degrees) by systematically manipulating the shape of the aperture, which was an elongated parallelogram. When the long edges of the aperture were not parallel to the drifting texture, the perceived direction of motion was close to the orientation of the long edges (as typically perceived in the BPI) and the orientation of the short edges had little impact on the perceived direction of motion. However, when the long edges were parallel to the drifting texture (resulting in no motion along these edges), the perceived direction of motion was close to the orientation of the short edges. The fact that a small change in the contour orientation of the short edges had little impact on the global shape of the aperture, but drastically affected the perceived direction of motion, suggests that the BPI can be mainly driven by the processing of line-ends along the aperture contour even under peripheral viewing conditions. These results suggests that the BPI viewed peripherally does not depend on the global shape of the aperture per se, but rather on the contours of the aperture.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".