Aging does not decrease spatial suppression in a motion step task
Bibliographic record
Abstract
Direction discrimination becomes more difficult as high-contrast stimuli increase in size and as low-contrast stimuli decrease in size (Tadin et al., Nature, 2003). However, although older adults show spatial summation at low contrast, they demonstrate no evidence for spatial suppression at high contrast (Betts et al., Neuron, 2005). It has been hypothesized that this behavioural finding occurs as a result of decreased GABAergic inhibition in the aging visual system (Leventhal et al., Science, 2003), but it is unclear whether the finding extends to other tasks; for example, static tasks have not shown the same effects of aging (Karas & McKendrick, J Vis, 2009; Farber et al., VSS 2010 & 2011). Recently, Churan et al. (J Vis, 2009) described results from a motion step task consistent with summation at low contrast and suppression at high contrast for younger subjects, providing us with an opportunity to examine the effects of aging in another paradigm using brief motion stimuli. In the current study, we tested six younger and four older adults in this task. A vertically-oriented 0.5 cpd Gabor stimulus remained static in the center of the screen for 35 ms, and then, after a brief motion step, the phase-shifted gabor was presented for another 35 ms. A 2-down, 1-up staircase manipulated the size of the phase jump (1-89 deg) required to correctly determine the motion direction. There were four blocks, one for each combination of contrast (1.5, 98%) and size (4.56, 17.68 deg). Results from younger subjects replicated the findings from Churan et al. (2009), and older adults also demonstrated this pattern of spatial summation at low contrast and spatial suppression at high contrast. Hence, we found no evidence of an age-related reduction in spatial suppression in this task, suggesting that the phenomenon may be limited even for brief motion stimuli. Meeting abstract presented at VSS 2013
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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) | 0.001 | 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 | 0.000 |
| 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".