... Before speculating on the mechanism in which alpha suppression relates to psychedelic imagery, it is important to note other conditions in which alpha power decreases. These are: visual stimulus with eyes open (Hanslmayr, et al., 2007;Klimesch, 2011) or closed (Pfurtscheller and Aranibar, 1977), increased attention (Foxe, et al., 1998;Kelly, et al., 2006;Worden, et al., 2000), increased anticipatory attention (Bastiaansen and Brunia, 2001), mental imagery (Salenius, et al., 1995;Schupp, et al., 1994;Slatter, 1960), increased attention to details of mental imagery (Salenius, et al., 1995), phasic-REM (with eye movements) compared to tonic-REM 1. BACKGROUND (without eye movements) (Cantero, et al., 1999), and with stimulants such as amphetamine, cocaine and caffeine (Deslandes, et al., 2005;Fink, 1969;Monnier, 1957;Pfeiffer, et al., 1965;Siepmann and Kirch, 2002). ...