Orientation discrimination threshold-as-a-function-of-size curves shift more dramatically with increased stimulus contrast at 0 than 10 degrees in the temporal visual field
Bibliographic record
Abstract
PURPOSE. Performance on many tasks can often be made equal across the visual field by appropriate scaling (F) of stimuli at all eccentricities according to [F=1+E/E2], where E2 indicates the eccentricity at which the size of the stimulus must be doubled, relative to the foveal standard, to achieve equivalent performance. Sally and Gurnsey (2004, Vision Research) have noted that E2s are larger at near-detection-threshold levels of stimulus contrast. This situation would arise if there was a relatively greater change in orientation thresholds as a function of stimulus contrast at the fovea than in the periphery, perhaps owing contrast-dependent changes in receptive field structure. METHODS. Stimuli were broadband line patterns of 2 different aspect ratios (width 2.75 and 11 percent of height) presented at a range of sizes (0.2 to 36 deg.) at 0 and 10 degrees in the temporal periphery. Orientation discrimination thresholds were obtained for all stimuli at 3 levels of Michelson contrast (3, 12 and 48%). RESULTS. For each aspect ratio, E2s increased from about 2.5 deg. at 48% contrast to 6 deg. at 3% contrast. The critical line sizes marking the transition to asymptotic orientation thresholds at large stimulus sizes changed to a greater extent (factor of 1.3 to 2.3) with increasing stimulus contrast at the fovea than in the periphery. CONCLUSIONS. Less spatial scaling is required to equate foveal and peripheral performance at low contrast; this is related to a greater overall change in orientation thresholds as a function of contrast at the fovea.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".