Regularity and beyond: Impaired production and comprehension of inflectional morphology in semantic dementia

Abstract

Studies on inflectional morphology in semantic dementia (SD) have focused on the contrast between the regular and the irregular English past-tense. These studies aimed to contrast the claims of single- and dual-mechanism theories. However, both theories can account for impaired production of irregular verbs observed in SD. According to the dual-mechanism theory, this impairment is related to word-retrieval difficulties, while according to single-mechanism theory it is the consequence of semantic impairment. However, authors suggest that it is time to envision a broader role for semantic memory in the production of semantically encoded aspects of inflectional morphology. This study reports the performance of 10 French-speaking patients with SD in three tasks of inflectional morphology. Their performances were compared to those of a group of 20 age-, gender- and education-matched adults without cognitive impairment. Results show that SD patients had difficulties producing tense and person inflection in verbs and pseudo-verbs, whether regular or pseudo-regular. In a second task in which participants were directly exposed to regularity manipulations, SD patients tended to choose a more typical or predictable alternative over a correctly inflected verb. Results of the third task show that their difficulties in producing semantically encoded aspects of inflection, such as tense, are related to difficulties to understand the semantic content conveyed by inflectional morphemes. Overall, these results support the claim that semantic impairment can cause morphological deficits that do not only affect irregular verbs, but that also have impacts on the production and comprehension of semantic information conveyed by inflectional morphemes.

The Role of the Left Anterior Temporal Lobe for Unpredictable and Complex Mappings in Word Reading

“…Thus, although regular words with complex OPM can be correctly read through sublexical processes, their reading might be facilitated by the use of the whole-word reading network. Interestingly, Auclair-Ouellet et al (2016) found that the semantic impairment in svPPA patients affected morphological processes for both exception and regular verbs. Thus, the degradation of semantic knowledge conveyed by units such as morphemes or graphemes would not solely impact exception word processing but also regular words with complex OPM.…”

Mental Time Travel and Time Reference Difficulties in Alzheimer’s Disease: Are They Related? A Systematic Review

“…The reasons put forward to explain those difficulties included impairments of rule processing or lexical retrieval ( Pinker, 1998 ), which would be related to impairments of procedural and declarative memory, respectively ( Ullman et al, 1997 ). Because the double dissociations in regular and irregular verb impairment put forward by these models were not systematically observed (e.g., Faroqi-Shah and Thompson, 2004 , 2007 ; Faroqi-Shah, 2007 ; Macoir et al, 2013 ; Auclair-Ouellet et al, 2016 , 2018 ), other models suggested that the difficulties were related to phonological or semantic processing impairments (e.g., Joanisse and Seidenberg, 1999 ; McClelland and Patterson, 2002 ; Faroqi-Shah and Thompson, 2004 , 2007 ; Bastiaanse et al, 2011 ). Regarding the latter explanation, it was proposed to explain difficulties mostly when producing the past tense of irregular verbs in English, but a few studies considered a more conceptual contribution to morphology.…”

“…Psycholinguistic models of inflectional morphology generally explain deficits in terms of rule-processing impairments, phonological-encoding impairments, lexical-retrieval impairments, or reductions in cognitive resources (e.g., Ullman et al, 1997 ; Pinker, 1998 ; Faroqi-Shah and Thompson, 2004 , 2007 ; Bastiaanse et al, 2011 ). However, studies of patients with post-stroke aphasia and primary progressive aphasia (PPA) suggest that those difficulties may be related to semantics, and more specifically to time conceptualization (e.g., Bates and Wulfeck, 1989 ; Auclair-Ouellet et al, 2016 ; Mack et al, 2021 ). Because it is known that semantic difficulties in AD become more severe with the progression of the disease, the question of whether time reference impairments may emerge as a result of time conceptualization impairments can be asked.…”

Embodied Cognition over the Lifespan and in Applied Settings

“…AD patients were recruited in Quebec City (Quebec, Canada) in the community, in a community center, or in the pool of patients already followed in our laboratory. SD patients were recruited from a larger project conducted in Quebec City (see Auclair-Ouellet et al, 2016). Participants in the HE group were recruited through public announcements and in two community centers in Quebec City.…”