Figure 3
Results of Experiment 2. Accuracy (a) and reaction times (b) as a function of number of elements when elements were located on the vertices of an equilateral triangle (red) or random (green). (c) Grand average ERPs collapsed across number of elements for triangle (red) and random (green) configurations. The ERPs are an average of the six electrodes (P7, P8, PO5, PO6, PO7, PO8) used to quantify the N1 and N2 components and highlights the N2 effect analysed between 250 and 400 ms after stimulus onset (yellow region and difference topography between all shape and random conditions). Blue regions represent periods of stable topographic differences determined by the TANOVA. (d) Grand average ERPs collapsed across spatial configuration for different number of elements. The ERP waveforms, averaged across electrodes FC1, FC3, C1, and C3, display an effect of numeric quantity between 400 and 650 ms (yellow region and difference topography) over mid-left frontal electrode sites. The difference topography is the difference between low (3, 4) minus high (5, 6) number of elements, irrespective of spatial configuration. TANOVA (blue regions) also represent differences between low (3, 4) versus high (5, 6) number of elements. (e) Onset and offsets of topographic microstates for all eight conditions. Horizontally oriented bars show the point in time when microstate periods change for each condition of the experiment (R3—random configuration with 3 elements, through to S6—triangle configuration with 6 elements). Each map is represented by a different colour. Global Field Power waveforms are displayed for a visual comparison to topographic microstates. (f) Four topographic microstates derived from the segmentation procedure which best fit the individual subject data. Topographic maps show the head from above with nasion plotted upward.
