In this session participants completed a total of five blocks of the MATB task.
Data were recorded continuously during each 5-min run of the MATB task.
The participant-specific functions were developed on samples of EEG data taken from the baseline block of data for each participant from the HL and PW versions of the MATB task, and then they were tested on data samples from the last two test blocks.
These results thus indicate that from the participant's perspective, the stimulus and response manipulations were effective at varying the composite difficulty of the MATB task.
Measures of overt task performance in the MATB task are also summarized in Table 1.
The purpose of this analysis was to determine whether the index values produced by the multivariate EEG task load functions that were derived for each participant would succeed in distinguishing between MATB conditions that varied in difficulty.
For comparison purposes, each participant's overall subjective task load ratings are also included in Table 3, as are his or her mean RTs in the monitoring subtask, because that subtask was included in all difficulty versions of the MATB and because the RTs in that subtask were highly sensitive to the experimental manipulations.
The present results are thus consistent with these views, implying that performance of the more difficult versions of the MATB task placed high demands on frontal brain circuits involved with attention control.
Alpha activity was found to systematically decrease in power as the MATB versions increased in difficulty.
Such results suggest that as task difficulty in the MATB increased, there was increased commitment of cortical resources to task performance.