Abstract
Language assessment using a picture naming task crucially relies on the interpretation of the given verbal response by the rater. To avoid misinterpretations, a language-specific and linguistically controlled set of unambiguous, clearly identifiable and common object–word pairs is mandatory. We, here, set out to provide an open-source set of black and white object drawings, particularly suited for language mapping and monitoring, e.g., during awake brain tumour surgery or transcranial magnetic stimulation, in German language. A refined set of 100 black and white drawings was tested in two consecutive runs of randomised picture order and was analysed in respect of correct, prompt, and reliable object recognition and naming in a series of 132 healthy subjects between 18 and 84 years (median 25 years, 64% females) and a clinical pilot cohort of 10 brain tumour patients (median age 47 years, 80% males). The influence of important word- and subject-related factors on task performance and reliability was investigated. Overall, across both healthy subjects and patients, excellent correct object naming rates (97 vs. 96%) as well as high reliability coefficients (Goodman–Kruskal's gamma = 0.95 vs. 0.86) were found. However, the analysis of variance revealed a significant, overall negative effect of low word frequency (p < 0.05) and high age (p < 0.0001) on task performance whereas the effect of a low educational level was only evident for the subgroup of 72 or more years of age (p < 0.05). Moreover, a small learning effect was observed across the two runs of the test (p < 0.001). In summary, this study provides an overall robust and reliable picture naming tool, optimised for the clinical use to map and monitor language functions in patients. However, individual familiarisation before the clinical use remains advisable, especially for subjects that are comparatively prone to spontaneous picture naming errors such as older subjects of low educational level and patients with clinically apparent word finding difficulties.
Highlights
The correct identification and semantic retrieval of object names in a behavioural task is the basis of investigating conceptual knowledge of objects in the human brain [1]
Healthy Subjects Overall, mean correct object recognition and picture naming rates were in the range of 98 ± 4 and 97 ± 4% and were significantly higher in the second as compared to the first run
This work provides the first freely available data set of pictures, developed for experimental and clinical use, for German-speaking subjects
Summary
The correct identification and semantic retrieval of object names in a behavioural task is the basis of investigating conceptual knowledge of objects in the human brain [1]. Different linguistic factors are known that affect the ease of the retrieval process and task performance in general. Three of these important factors are addressed in this work: First, the uniqueness of the object drawing to be named and the disambiguity of the corresponding word to be retrieved are crucial pre-requisites of reliable testing and calls for objects that can be depicted graphically as well as for the non-existence of alternative expressions (i.e., synonyms) to name the respective object [see [3] for review]. With respect to age or educational level as well as cultural background and language so that existing stimuli and procedures cannot be directly transferred from one language to another [8, 9]
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