Low-level mechanisms may contribute to paradoxical motion percepts
Bibliographic record
Abstract
A recent series of experiments demonstrated a surprising deterioration of visual motion discrimination with increasing stimulus size for stimuli of high contrast. This counterintuitive finding was explained as a result of surround suppression in visual area V5. Equally paradoxical was the finding that older observers showed better performance than younger observers. This second result was explained as an age-related reduction in surround suppression due to changes in GABA-mediated inhibition. Using an opponent motion stimulus, we find an analogous effect and also find that this effect is much reduced in older observers, to the point where they perform better than younger observers. Our long duration stimulus should be beyond the range at which surround-suppressed neurons in V5 are preferentially activated. Having normalized our stimuli relative to contrast threshold, we show that our results can be entirely explained by the relative contrast of the stimulus and speculate that contrast sensitivity may play a role in previously reported results. Our older observers' data similarly can be explained by the relative contrast of the stimulus. The difference between older and younger observers appears to be a result of a weakening of spatial summation at high contrast in younger observers, perhaps caused by earlier saturation of motion mechanisms.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| 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 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".