Researchers have published evidence supporting both the “working memory” and the “REM/Orienting Response” hypotheses as mechanisms underlying the documented treatment effects of EMDR on patients with posttraumatic stress disorder. Hornsveld et al. (2011) provide additional evidence of the impact of eye movements (EMs) on aspects of positive memory recall, but overstate their findings relevance to resource development and installation (RDI: Korn & Leeds, 2002) and to the interhemispheric interaction hypothesis (Propper & Christman, 2008). Most likely multiple mechanisms underlie the observed effects of EMDR and RDI. The needed RDI test is to randomly assign patients with Disorders of Extreme Stress not Otherwise Specified with measured coping difficulties to alternate conditions: one an RDI procedure without bilateral (or other distracting) sensory stimulation and one with bilateral EMs.