Simultaneous contrast is size dependent but does not scale with eccentricity
Bibliographic record
Abstract
Purpose: Simultaneous contrast demonstrates that a uniform grey is seen as darker on a white background than on a black background. The phenomenon can be easily understood in terms of centre-surround mechanisms known to exist throughout the visual system. The sizes of these mechanisms are known to increase with eccentricity. Therefore, we ask whether the strength of the simultaneous contrast illusion changes with stimulus size and eccentricity. Method: Stimuli comprised five square regions stacked to form a vertical rectangle. Region 2 (the standard) was of fixed luminance (.5) and subjects adjusted the luminance or region 4 (the match) to match that of region 2. Regions 1 and 5 contained luminance gradients from 0 to 1 [/] and region 3 contained a luminance gradient going from 1 to 0 [\]. Therefore, the cross-section of a stimulus going from top to bottom would be: [/—\—/]; i.e., region 2 was surrounded by white and region 4 by black. Stimuli were presented at 9 logarithmically spaced sizes ranging from 102 to 1152 pixels at eccentricities of 0, 1, 2, 4 to 8° in the right visual field. Results: Under free viewing conditions (stimuli presented nominally at 0°) matches were veridical (.5) at small sizes and decreased (e.g., to .30) as stimulus size increased; i.e., the standard illusion was seen at large stimulus sizes. Similar results were found when subjects maintained fixation on a small dot and stimuli were presented at 0 to 8°. Unlike standard size scaling results, however, the functions relating stimulus size to match luminance were not shifted versions of each other on a log size axis. The curves at 0 to 4° were essentially superimposed and that at 8° was shifted rightward. Conclusions: Although simultaneous contrast is size dependent it does not show typical eccentricity dependence.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.007 |
| 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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".