We evaluated whether lexical selection in speech production is affected by word frequency by means of two experiments. In Experiment 1 participants named pictures using utterances with the structure "pronoun + verb + adjective". In Experiment 2 participants had to perform a gender decision task on the same pictures. Access to the noun's grammatical gender is needed in both tasks, and therefore lexical selection (lemma retrieval) is required. However, retrieval of the phonological properties (lexeme retrieval) of the referent noun is not needed to perform the tasks. In both experiments we observed faster latencies for high-frequency pictures than for low-frequency pictures. This frequency effect was stable over four repetitions of the stimuli. Our results suggest that lexical selection (lemma retrieval) is sensitive to word frequency. This interpretation runs against the hypothesis that a word's frequency exerts its effects only at the level at which the phonological properties of words are retrieved.

Objective: To assess the internal construct validity (ICV) of the five Brain Injury Rehabilitation Trust Personality Questionnaires (BIRT-PQ) with Classical Test Theory methods. Methods: Multicenter cross-sectional study involving 11 Italian rehabilitation centers. BIRT-PQs were administered to patients with severe Acquired Brain Injury and their respective caregivers. ICV was assessed by the mean of an internal consistency analysis (ICA) and a Confirmatory Factor Analysis (CFA). Results: Data from 154 patients and their respective caregivers were pooled, giving a total sample of 308 subjects. Despite good overall values (alphas ranging from 0.811 to 0.937), the ICA revealed that several items within each scale did not contribute as expected to the total score. This result was confirmed by the CFA, which showed the misfit of the data to a unidimensional model (RMSEA ranging from 0.077 to 0.097). However, after accounting for local dependency found within the data, fitness to a unidimensional model improved significantly (RMSEA ranging from 0.050 to 0.062). Conclusion: Despite some limitations, our analyses demonstrated the lack of ICV for the BIRT-PQ total scores. It is envisaged that a more comprehensive ICV analysis will be performed with Rasch analysis, aiming to improve both the measurement properties and the administrative burden of each BIRT-PQ.

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