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TvN data from the 82% level of performance were first fit using the LAM to determine the nature of observed differences. We focused on the 82% correct data because the LAM does not differentiate mechanisms at different performance levels and we have full datasets for all seven subjects at the 82% level. When comparing performance at the originally selected blind field locations before and after training, as well as with matched locations in the intact field, improved performance in the low external noise conditions would indicate that training reduced the amount of internal noise in the system, whereas improvements across all external noise levels would indicate that training increased sampling efficiency. Among 25 candidate models tested (see Methods ), the best-fitting model (R= 98.1%; four free parameters: A[pre], A[post], N, and E) was the model that assumed a change in equivalent internal noise and no changes in sampling efficiency. Specifically, before training, the blind field had 11.1 times more equivalent internal noise than the intact (good) field ( Figure 7A ). Visual training reduced the amount of internal noise at the trained blind field locations, but it still remained 6.9 times higher than the estimated internal noise in the intact field of vision ( Figure 7A ). Statistically, an F test comparing the models revealed that this reduced model was not different from the full model, F(2, 12) = 0.99, p = 0.40, which assumed that both equivalent internal noise and sampling efficiency differed across the three conditions. However, the reduced model was substantially better than the no-difference model, F(2, 14) = 307.7, p < 0.0001, which assumed no changes across the three conditions ( Table 3 ). Other candidate models either provided significantly worse fits compared to the full model, or had more free parameters than the best-fitting model. In summary, in the blind field, the best-fitting LAM suggested that perceptual training in the blind field reduced equivalent internal noise by 38%. However, the recovered visual processing still had ∼7 times more equivalent internal noise than the intact visual field.