Early conceptions of aptitude were concerned with explicit learning abilities in formal learning settings, which according to MLAT (Modern Language Aptitude Test) were measurable based on a phonemic coding ability, an inductive learning ability, an associative memory, and a grammatical sensitivity (Carroll, 1962). However, recent understanding on aptitude has expanded Carroll's (1962) propositions by exploring the manifestations of aptitude's roles beyond conscious learning (Li, 2020). In other words, while aptitude has largely been conceived as explicit learning abilities in instructional settings, current research is shedding light on implicit aptitude and cognitive abilities that are activated during the unconscious processing of learning materials (i.e., in naturalistic learning settings). Clearly, there is a need for implicit learning to be investigated in light of implicit aptitude, instead of merely focusing on the explicit learning process and its outcome.