Psychophysical measurements of surround suppression in 5-year-olds
Bibliographic record
Abstract
At low contrasts, increasing stimulus size can improve performance, a phenomenon known as spatial summation. At high contrasts, young adults show spatial suppression: worse direction discrimination as stimulus size increases (Anderson & Burr, 1991; Betts et al., 2005; Tadin et al., 2003). Such spatial suppression has been attributed to GABA mediated inhibitory connections among cortical cells (Jones et al., 2001). Recent results suggest that children may have decreased GABAergic inhibition (Boley et al., 2005); if so, they should show decreased spatial suppression. Methods. To assess changes in spatial suppression with age, we measured motion discrimination thresholds as a function of pattern contrast and size in 27 5-year-olds and 24 young adults. In 4 separate blocks, participants viewed small (2σ = 0.7°) or big (2σ = 5°) 1 cpd Gabor patterns of high (92%) or low (4%) contrast, moving at 8°/sec. Participants judged the direction of motion as leftward or rightward. Stimulus duration varied over trials to determine the minimum duration needed for accurate performance. Results. At low contrast, duration thresholds were 1.9 times longer for children than adults (p 0.30). At high contrast, thresholds were worse for big than small patterns (p [[lt]]0.00001) and worse for children than adults (p = 0.03). The amount of spatial suppression was smaller in children than adults (p = 0.03, 1-tailed) because children were worse than adults for small but not big patterns. Conclusion. In general, 5-year-olds require more time than young adults to process the direction of motion. Critically, at high contrasts, the suppression index is smaller in 5-year-olds than adults, consistent with the hypothesis that 5-year-olds, like the elderly (Betts et al., 2005), have weaker inhibitory surrounds than young adults.
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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 | 0.001 |
| 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 | 0.000 |
| 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".