Colour and achromatic contrast adaptation: different adaptation effects at detection threshold and suprathreshold contrasts
Bibliographic record
Abstract
Prolonged viewing of chromatic contrast (adaptation) can increase detection thresholds as well as reduce the apparent contrast of subsequent stimuli. The selectivity of such effects across different stimuli of colour directions has been used to infer the tuning of distinct colour channels (e.g. Krauskopf, Williams & Heely, 1982, Vis Res). However, effects can vary across paradigms (e.g. Gunther, 2014, JOSA), and adaptation effects on threshold vs suprathreshold stimuli may be mediated by different mechanisms (e.g. Webster & Mollon, 1994, Vis Res). Here, we compared the effects of adaptation on detection thresholds and suprathreshold apparent contrast for counter-phasing sinusoidal ring stimuli (TF=2Hz, SF=0.5cpd, radius=7.5 degs). We measured the effect of adapting to achromatic (Ach), L-M isoluminant (RG) and S-cone isolating (BY) contrast on detection thresholds (n=10) and apparent contrast (n=10) of Ach, RG and BY test stimuli. As expected, within-stimulus adaptation was stronger than cross-stimulus adaptation for all stimuli across both paradigms, however, cross-stimulus adaptation effects varied significantly. After chromatic adaptation, achromatic test stimuli showed elevated detection thresholds but no change in apparent contrast. Conversely, after achromatic adaptation, chromatic test stimuli had unchanged detection thresholds but reduced apparent contrast. These results demonstrate that the effects of adaptation on detection thresholds are not predictive of the effects of adaptation on suprathreshold contrast appearance, suggesting that different mechanisms are being adapted in each case. Additionally, the cross-adaptation effects cannot be explained by simply assuming the mechanisms are more broadly tuned, with the asymmetries across stimuli suggesting more complex interactions.
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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 | 0.000 | 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 | 0.001 |
| 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".