Fig 1.
Experimental design and conditions.
(A) Spoken-word stimuli recorded with a dummy head were presented to the participant. In the acoustic scene, the two speakers appeared at ± 40 degrees of the participant’s head mid-line. (B) The stimulus onset asynchrony (SOA) was 1 s, leaving about 400-ms silent interval between consecutive stimuli. The black triangles indicate stimulus onsets. (C) The high- and low-pitch version of the words alternated (standard) but occasionally two same-pitch words were presented consecutively (deviant). (D) Classifiers were trained with trials extracted randomly across the entire recording (random training), or with trials only from the beginning of the recording (early training), or with trials extracted randomly from the latter half of the measurement (random late training), or with trials from the middle of recording (middle training).
Fig 2.
Layout of the EEG channel selections in the measurement.
The 64-channel EEG set (all dots), and the subsets of 30 (blue dots and all circles), nine (all blue circles) and three (thick blue circles) channels.
Fig 3.
Classification accuracy and information transfer rate (ITR) as a function of the measurement set-up and the number of combined trials.
(A) Classification accuracy when classifiers were trained with 25% of the data extracted randomly across the entire recording (grey) or with only the first quarter of the data (blue, green). (B) Classification accuracy when classifiers were trained with the middle blocks B9–B12 and tested with last four blocks B13–B16. The dots in panels A and B represent the mean accuracy across the 11 participants, and the shading the standard error of mean. (C) Information transfer rate as bits/min with training as in panel A. (D) Same as in Panel C but training as in Panel B. The dots in Panels C and D represent the mean ITR across the 11 participants, and the shading the standard error of mean.
Fig 4.
Classification accuracy as a function of the amount of training data.
The dots in the learning curves represent the mean classification accuracy across the 11 participants. The shading indicates the standard error of mean calculated over 20 iterations to each training set size.