“…MEI involves an environmental history of differential reinforcement where training involves rotation between operants such as echoics, listener responses, and tacts to each stimulus (Fiorile & Greer, 2007;Gilic & Greer, 2011;Greer & Longano, 2010;Greer & Ross, 2008;Greer, Stolfi, Chavez-Brown, & Rivera-Valdes, 2005;Greer, Stolfi, & Pistoljevic, 2007;Holth, 2017;LaFrance & Tarbox, 2019;Nuzzolo-Gomez & Greer, 2004). Rather than teaching echoics separately, Greer and colleagues (e.g., Fiorile & Greer, 2007;Gilic & Greer, 2011;Greer & Longano, 2010;Greer & Ross, 2008;Greer et al, 2005;Greer et al, 2007) have usually provided opportunities for echoic responses during matching-to-sample (MTS) in which the researcher tacts the sample stimulus.…”