Errorless, Errorful, and Retrieval Practice for Naming Treatment in Aphasia: A Scoping Review of Learning Mechanisms and Treatment Ingredients

Purpose: Increasingly, mechanisms of learning are being considered during aphasia rehabilitation. Well-characterized learning mechanisms can inform "how" interventions should be administered to maximize the acquisition and retention of treatment gains. This systematic scoping review mapped hypothe-sized mechanisms of action (MoAs) and treatment ingredients in three learning -based approaches targeting naming in aphasia: errorless learning (ELess), error-ful learning (EFul), and retrieval practice (RP). The rehabilitation treatment specification system was leveraged to describe available literature and identify knowl-edge gaps within a unified framework.Method: PubMed and CINHAL were searched for studies that compared ELess, EFul, and/or RP for naming in aphasia. Independent reviewers extracted data on proposed MoAs, treatment ingredients, and outcomes.Results: Twelve studies compared ELess and EFul, six studies compared ELess and RP, and one study compared RP and EFul. Hebbian learning, gated Hebbian learning, effortful retrieval, and models of incremental learning via lexi-cal access were proposed as MoAs. To maximize treatment outcomes within theorized MoAs, researchers manipulated study ingredients including cues, scheduling, and feedback. Outcomes in comparative effectiveness studies were examined to identify ingredients that may influence learning. Individual-level var-iables, such as cognitive and linguistic abilities, may affect treatment response; however, findings were inconsistent across studies.Conclusions: Significant knowledge gaps were identified and include (a) which MoAs operate during ELess, EFul, and RP; (b) which ingredients are active and engage specific MoAs; and (c) how individual-level variables may drive treat-ment administration. Theory-driven research can support or refute MoAs and active ingredients enabling clinicians to modify treatments within theoretical frameworks.