Figure 1. Results of Makin et al. (2020). The grand-average
ERPs are shown in the upper left panel and difference waves
(symmetry-random) are shown in the lower left panel. A large SPN is a
difference wave that falls a long way below zero. Topographic difference
maps are shown on the right, aligned with the representative stimuli.
The difference maps depict a head from above, and the SPN appears as
blue at the back. Purple labels indicate electrodes used for ERP waves
[PO7, O1, O2 and PO8]. SPN amplitude increases (that is, becomes
more negative) with the proportion of symmetry in the image. In this
example, the SPN increased from approximately 0 to –3.5 microvolts as
symmetry increased from 20% to 100%. Figure from Makin et al. (2022).
Derpsch et al. (2019) found that whilst the brain response to symmetry
can be enhanced when symmetry is presented in attended regions of the
screen, it is still robust when symmetry is presented unattended
regions. In addition, Derpsch et al. (2021) found that the SPN is not
diminished by a concurrent visual working memory task, suggesting the
SPN is also robust to variations in visual memory load. In the current
work, we extended this research program by investigating the SPN is
equally sensitive to alcohol-induced changes in mental state.