Centre-surround interactions on apparent contrast endure with broad-band stimuli
Bibliographic record
Abstract
When a narrow-band target is presented at the fovea and is flanked by a stimulus with the same spatial characteristics, its apparent contrast is reduced by ~40%. This effect is tuned to orientation and spatial frequency (about one octave). Our objective was to verify whether increasing stimulus complexity (by using broad-band gratings) affects this well-known contrast induction phenomenon (i.e., do suppressive interactions persist when multiple spatial and orientation channels are solicited). The stimuli consisted of cosine luminance gratings that contained multiple spatial frequencies or orientations. The central target had a diameter of 1 deg and the surround a diameter of 6 deg. Contrast was set at 40% for all patterns and all conditions. We used a contrast-matching paradigm that consisted of a two-alternative TFC procedure and the method of constant stimuli. We found that the apparent contrast of a single grating target remains equally reduced (~40% reduction) when the compound surround includes gratings that have a spatial frequency within 0.5 octave and an orientation within 15 deg of the target in addition to a grating with the same characteristics as the target. However, suppression in the apparent contrast of the target is reduced by half (~23 %) when the compound surround includes gratings that have a spatial frequency beyond 1.0 octave and an orientation beyond 30 deg of the target in addition to a grating with the same characteristics as the target. Finally, when the same compound grating is presented in the centre and surround, regardless of the spatial frequencies and orientations included, maximum suppression occurs (~38%). Therefore, suppressive interactions are not a narrow-band or single channel phenomenon, but also occur under a visual context that includes multiple spatial frequencies and orientations. Meeting abstract presented at VSS 2012
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| 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".