decoding in the error trial was significantly lower than decoding in the matched correct trials (trial ‘‘0’’ in the figure; t24 = 2.3, p = 0.01) and marginally lower in the trial prior to the error
Results, paragraph 13; Figure 4B
What the paper reports
- trial 0: t-test, t24 = 2.3, p = 0.01
- trial -1: t-test, t23 = 1.5, p = 0.07
Matched to their class, error trials do not decode worse. Every error trial with a state is an Enter trial, and correct Enter trials decode at 0.90% with maps z-scored by voxel, against 11.79% for Exit and 14.30% for Internal trials. Error trials 1.59% against 1.42% at position 0 of matched courses (a) with an Enter trial there (t20 = 0.18, one-sided p = 0.57), and against 0.88% on all correct Enter trials (p = 0.68); p >= 0.45 in every reading. The criterion's readings, which do not match class, differ. With maps z-scored by voxel and matched courses (a), error trials are lower (1.59% against 9.21%, t20 = -4.07, one-sided p = 0.0003; strict reading 2.08% against 8.93%, p = 0.005); with one matched course per error (b) p = 0.044 to 0.14; with maps z-scored by map the error trial is not lower (p >= 0.69). Trial -1 is not lower by voxel (11.59% against 8.81%, one-sided p = 0.70; paper p = 0.07). 21 participants, so t20 where the paper gives t24. With maps z-scored by voxel, reading (c) is at floor (1.59% against 1.42% and 0.88%, below the 6.25% chance level), because that classifier names an Enter state on 5.60% of labelled volumes, and could not show a drop. The reading that could is the map z-scoring, where labelled Enter trials decode at 8.02%, and there the error trial is not lower under the criterion's readings (p >= 0.69) or under (c) (p >= 0.45). Changed from reproduced after verification round 1.
How the test differed from the paper’s method
- Assumed a class-matched comparison, reading (c), position 0 against matched courses whose position 0 is an Enter trial. The criterion's matched courses (a) and (b) do not match class; the paper's error trials were of all three classes and its matched courses of the same mix, while here only Enter errors can be given a state, so only a class-matched comparison compares like with like. That the paper's matched courses had the class mix of its error trials is an inference; the Figure 4B legend says only "seven consecutive trials with no behavioral error".
- As fig4b-error-trial-drop for smoothing and error states.