The nature of neologisms in aphasia: an experimental study in three patients

Aims: to investigate the nature and the evolution of neologisms in jargonaphasic patients. Material: three patients (two females – DLP and LM – and one male - DLC), affected by aphasia following left hemisphere ischemic stroke, were included in the study. All patients underwent standard language assessment. Neologistic production was specifically studied using confrontation naming, reading aloud and repetition tasks, in which stimuli (n= 30, 124 and 124, respectively) were matched for length, consonant clusters, frequency and imageability. Follow-up assessments were carried out at 6-7 month intervals (DLP and DLC: 3 assessments; LM: 2 assessments), during which all patients were treated by experienced speech therapists. Methods: incorrect responses were classified as no responses, phonemic paraphasias ), semantic paraphasias and neologisms. Errors were further classified as additions, omissions, substitutions and transpositions. Quantitative response-to-target comparisons were performed by calculating the Phonological Overlap Index (POI, Bose et al, 2007) and a newly developed Phonological Correspondence Index (PCI), which provides a more sensitive measure of transpositions. Neologisms were further classified as target-related or non target-related (bizarre) based on the number of phoneme errors relative to the target length. Length and cluster effects (linked to postlexical deficits) as well as frequency and imageability (linked to lexical deficits) were analyzed. Results: in all patients, naming was the most impaired and reading aloud the least impaired task. Substitutions represented the most frequent type of errors and errors on consonants were more frequent than errors on vowels. Length, frequency and imageability effects were different across patients. Longitudinal observation over time suggests that in the course of recovery neologisms evolve toward progressively fewer phonological errors. Discussion: The analysis of neologistic responses revealed that different mechanisms can contribute to their production in different patients, suggesting that no single source of neologisms can be identified in all cases of jargonaphasia. Rather, with reference to Patterson’s (1986) model, different profiles of lexical and/or postlexical deficits can be hypothesized in different patients, depending on functional site(s) of lesion. References: Bose, A., Raza, O., Buchanan, L., (2007). Phonological relatedness between target and error in neologistic productions. Brain and Language, 103, 120-121. Patterson, K.E. (1986) Lexical but non semantic spelling? Cognitive Neuropsychology, 3, 341-367.