Effect of aging on the use of orientation and position in shape perception
Bibliographic record
Abstract
Grouping local elements to extract shapes is a crucial task of the visual system. Recently, Day and Loffler (2009) showed that shape perception results from a weighted combination of local element positions and orientations, and the weighting of each cue depends on their relative strength. When elements whose orientations were consistent with a pentagon were positioned on circle, the orientation information dominated the percept and a pentagon shape was perceived. With increasing number of elements, the position information became more dominant and a circular shape was perceived. Shape discrimination is unaffected by healthy aging (Habak et al., 2009). However, older adults are less influenced by local orientation information when integrating contours (Roudaia et al., 2008). Here, we examined whether the relative roles of orientation and position information in shape perception change with age. Following Day and Loffler (2009), conflicting target stimuli were created by sampling the orientation of a rounded pentagon with Gabors and positioning them on a circle. Test stimuli were composed of Gabors whose positions and orientations were consistent with pentagon shapes of varying amplitude. On each trial, older (∼ 66 yrs) and younger (∼ 24 yrs) subjects viewed a target and test stimuli in two intervals and judged which shape looked more circular. The amplitude of the test stimulus was varied to measure the point of subjective equality between the perceived target and the test shapes. The number of Gabors comprising the stimuli was varied to manipulate the strength of position information. Consistent with previous findings, the perceived target shape was consistent with a pentagon for stimuli comprising 15 - 40 elements. This orientation dominance effect disappeared with denser sampling. Interestingly, this effect was equal in older and younger subjects across all sampling levels. These results support the findings that shape perception mechanisms are preserved in older age.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.003 | 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".