Supplementary Materials

Neural correlates underlying insight problem solving: Evidence from EEG alpha oscillations

Complementary analysis

As several main ERP indicators like P300, N500 etc. are between 100 ms and 800 ms and Figure 2 also demonstrates that there is an increase of alpha power before 800 ms during successful condition in comparison to unsuccessful condition, we have conducted additional analyses in the 100-800 ms time interval. For the parieto-central electrodes, TRP changes of alpha power duringthe 100-800 ms time interval were analyzed using a 2 (condition: successful vs. unsuccessful) 8 (electrode site) repeated measures ANOVA. The results suggested that main the effects of condition and electrode site did not reach statistical significance [F(1, 14) = 0.277, p = 0.607, ηp2 = 0.019; F(7, 98) = 0.570, p = 0.644, ηp2 = 0.039, respectively], nor did the interaction between the two factors [F(7, 98) = 2.309, p = 0.082, ηp2 = 0.142].For the parieto-occipital electrodes, the TRP changes in the alpha band were analyzed using a 2 (condition: successful vs. unsuccessful)  14 (electrode site) repeated measures ANOVA. The results suggested that main the effects of condition and electrode site did not reach statistical significance [F(1, 14) = 1.864, p = 0.194, ηp2 = 0.117; F(13, 182) = 0.825, p = 0.499, ηp2 = 0.056, respectively], nor did the interaction between the two factors [F(13, 182) = 0.864, p = 0.501, ηp2 = 0.058].These result mainly indicated that for the parieto-central and parieto-occipital electrodes the main effects of condition (successful vs. unsuccessful) did not reach statistical significance. This is probably because during the 100-800 ms time window, the cognitive processes after the presence of target logogriphs were similar in the successful and unsuccessful conditions. For example, previous study has suggested that participants were understanding the superficial meaning of the target logogriphs before 800 ms(Qiu et al. 2008)

Complementary Figure 1.

Complementary figure 1 shows the amplitude of alpha TRP power changes at the CP1 and CP2 electrode sites.

Complementary Figure 2.

To select electrodes, alpha power changes in successful and unsuccessful conditions were averaged on each electrode(Cohen 2014).Complementary figure 2shows the decrease in alpha power over two conditions averaged together. From electrodes that showed a decrease in alpha power over two conditions averaged together, eight parieto-central electrode sites (CP3, CP1, P1, CPz, Pz, P2, CP2, CP4) and fourteen parieto-occipital electrode sites (P7, P3, PO7, PO5, PO3, O1, POz, Oz, O2, PO4, PO6, PO8, P4, P8) were selected.


Reference

Cohen MX (2014) Analyzing Neural Time Series Data: Theory and Practice. MIT Press

Qiu J, Li H, Yang D, Luo Y, Li Y, Wu Z, Zhang Q (2008) The neural basis of insight problem solving: an event-related potential study. Brain Cogn 68:100-106 doi: 10.1016/j.bandc.2008.03.004