Finding

palmer-huk-shadlen-2005.chronometric

Palmer J, Huk AC, Shadlen MN. The effect of stimulus strength on the speed and accuracy of a perceptual decision. Journal of Vision, 2005, 5(5):376-404. · Human random-dot motion button reaction-time task · chronometric

Observed curve and fits

Joint-fit companions

Other findings jointly fit by the same model fits.

Fit diagnostics

Caveats on these fits (2 terms)

Each tag below is attached to one or more candidate fits for this finding. The chip column in the table flags which row carries which tag.

chronometric-summary fit
Descriptive median-RT-by-strength fit over summary chronometric points, not a full reaction-time likelihood or process model.
aggregate DDM RT approximation
DDM likelihood uses aggregate chronometric constraints rather than a full trial-level response-time likelihood.
Variant AIC Δ AIC RMSE Caveats
chronometric-hyperbolic-rt winner 6.1 0.0 0.0194
  • chronometric-summary fit
chronometric-constant-rt 8.0 1.9 0.1455
  • chronometric-summary fit
ddm-vanilla 2238.2 2232.1 -
  • aggregate DDM RT approximation
ddm-drift-bias 2239.2 2233.1 -
  • aggregate DDM RT approximation
ddm-starting-point-bias 2240.2 2234.1 -
  • aggregate DDM RT approximation
Full diagnostics (logL · n · params · max abs error)
Variant logL n Free params Max |error| Predicted points
chronometric-hyperbolic-rt -0.1 3,373 3 0.0307 6
chronometric-constant-rt -3.0 3,373 1 0.2070 6
ddm-vanilla -1116.1 3,373 3 - 0
ddm-drift-bias -1115.6 3,373 4 - 0
ddm-starting-point-bias -1116.1 3,373 4 - 0

Residuals

Fit parameters and provenance

chronometric-hyperbolic-rt.palmer-huk-shadlen-2005.chronometric

dirty fit

half_saturation_strength=20.491 · rt_floor=0.225 · rt_span=0.592

Method
scipy.optimize.minimize
Commit
3ec74b4
Predicted points
6
BIC
5.5

Fitted with scipy.optimize.minimize via behavtaskatlas.model_fits.chronometric-hyperbolic-rt; success=True; CONVERGENCE: RELATIVE REDUCTION OF F <= FACTR*EPSMCH

chronometric-constant-rt.palmer-huk-shadlen-2005.chronometric

dirty fit

rt_level=0.617

Method
manual
Commit
3ec74b4
Predicted points
6
BIC
7.8

Fitted with manual via behavtaskatlas.model_fits.chronometric-constant-rt; success=True; closed-form weighted constant RT estimate

ddm-vanilla.palmer-huk-shadlen-2005.psychometric

dirty fit

boundary=0.998 · drift_per_unit_evidence=0.239 · non_decision_time=0.409

Method
scipy.optimize.minimize
Commit
10e1c18
Predicted points
0
BIC
2256.6

Fitted with scipy.optimize.minimize via behavtaskatlas.model_fits.ddm-vanilla; success=True; CONVERGENCE: RELATIVE REDUCTION OF F <= FACTR*EPSMCH

ddm-drift-bias.palmer-huk-shadlen-2005.psychometric

dirty fit

boundary=0.917 · drift_bias=0.008 · drift_per_unit_evidence=0.260 · non_decision_time=0.407

Method
scipy.optimize.minimize
Commit
10e1c18
Predicted points
0
BIC
2263.7

Fitted with scipy.optimize.minimize via behavtaskatlas.model_fits.ddm-drift-bias; success=True; CONVERGENCE: RELATIVE REDUCTION OF F <= FACTR*EPSMCH

ddm-starting-point-bias.palmer-huk-shadlen-2005.psychometric

dirty fit

boundary=0.998 · drift_per_unit_evidence=0.239 · non_decision_time=0.409 · starting_point=0.502

Method
scipy.optimize.minimize
Commit
10e1c18
Predicted points
0
BIC
2264.7

Fitted with scipy.optimize.minimize via behavtaskatlas.model_fits.ddm-starting-point-bias; success=True; CONVERGENCE: RELATIVE REDUCTION OF F <= FACTR*EPSMCH

Observed points

Absolute motion coherence median_rt_s n
0.000 0.7980 560
3.200 0.7680 564
6.400 0.6780 563
12.800 0.5880 554
25.600 0.4620 567
51.200 0.4100 565

Take it with you

Cover sheet

Self-contained Markdown for citation, slides, or notebooks

The cover sheet pins the finding to the atlas commit and includes the observed points, fit ranking, caveats, and provenance — everything needed to drop into a paper or notebook without losing the trail back to the deploy.