The effect of speed on the typical and atypical development of motion-defined form perception
Bibliographic record
Abstract
Our previous work on motion-defined form perception showed: 1) slow maturation to adult levels by 7 years of age, and 2) large fellow-eye deficits in children with amblyopia. These developmental changes could reflect the functioning of the M/dorsal or the P/ventral pathway. The current study used motion speed to bias the relative contribution of the M/dorsal (fast motion) and P/ventral (slow motion) pathways to the processing of motion-defined form. Motion-defined rectangles (vertical or horizontal) were created by moving a proportion of dots coherently (up or down) while the remaining dots moved in random directions at the same speed within the rectangle. Outside the rectangle, dots moved in the opposite direction with the same speed and coherence. Monocular motion coherence thresholds, for discriminating rectangle orientation, were determined at slow (0.85 deg/s) and at fast speeds (5.1 deg/s) using a staircase procedure. First we examined normal development in children (4–6 years), adolescents (11–12 years) and young adults. Consistent with our previous results, coherence thresholds were higher in children than in adolescents and adults, with no difference between the two older groups. In addition, coherence thresholds were lower at the slow than at the fast speed for all three groups. Next we examined patients aged 11 years and older with anisometropic and/or strabismic amblyopia. A few individuals showed a deficit in either eye at both speeds, and thresholds were lower in those with compromised binocularity. As a group, however, performance was similar to that of the controls. This is contrary to our previous results, possibly due to the older age of the observers or to the use of coherence rather than minimum-speed thresholds. Our results provide no evidence for a developmental difference in M/dorsal versus P/ventral pathways. The speed effect may reflect the stronger contribution of the slow-motion system to motion-defined form perception.
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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 | 0.001 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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 | 0.000 |
| 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".