“…Studies in SLA using a similar paradigm have also confirmed the spacing effect for vocabulary learning in one single session (Koval, 2022;Nakata, 2015;Nakata & Suzuki, 2019). There are different theories that try to account for the spacing effect, including the deficient processing, encoding VIAL n_21 -2024 variability or study-phase retrieval theories (see Edmonds, Gerbier, Palasis, & Whyte, 2021;Serrano, 2012;Toppino & Gerbier, 2014). The desirable difficulties theory proposed by Bjork (Bjork, 1994;2018) has received recent attention in the SLA literature (Rogers & Leow, 2020;Suzuki et al, 2019).…”