Fig 1.
Image presentation and the experimental procedure.
Subjects were shown the image of “+” for 0.5 seconds, text for 1.5 seconds, a blank image for 0.5 seconds, a facial expression for 1 second, and, finally, the participants were asked to choose a donation from 0, 2500, 5000, 7500, and 10000 yen. The reaction time was recorded. EEG was recorded for each facial presentation over a total period of 1200 ms starting at 200 ms before a given stimulus (baseline) and ending at 1000 ms after stimulation.
Fig 2.
Comparison of reaction times and donations in each condition.
Donations for PoSm are significantly greater than those for NeSm conditions. Asterisks in the figure denote significant differences.
Fig 3.
Illustration of the ERP waveform and the topographical map related to the EPN and LPP.
ERP waveforms for the right temporo-occipital (PO8/P8) and parietal sensor (P1-Pz-P2) for PoSm (dashed line) and NeSm (solid line) conditions. Topographical maps display the time interval plotted on a backward right (EPN) and back view (LPP).
Fig 4.
Comparison of mean amplitude of the LPP for each sensor area in the smile expression condition (left) and the angry expression condition (right).
There were significant differences at P1-Pz-P2 between the PoSm and NeSm conditions. On the other hand, there were no significant differences between the PoAn and NeAn conditions. Asterisks in the figure denote significant differences.