Figure 4.

PTM predictions. TvN comparisons between test conditions may present four possible signatures when fit with the PTM: (A) Lower thresholds at low-noise than high-noise conditions, indicating a reduction of additive internal noise in the better performing conditions compared to the impaired condition, suggestive of stimulus enhancement; (B) Improved performance only in high-noise conditions, suggesting an improved ability to exclude external noise when encoding the stimulus in the better performing condition compared to the impaired condition; (C) Improved performance at all noise conditions, but only at one difficulty level, indicating a reduction of multiplicative internal noise in the better performing condition compared to the impaired condition; (D) Lower thresholds at all noise levels and both difficulty levels, indicating a combined effect of reduced additive internal noise and improved external noise exclusion in the improved condition compared to the impaired condition.