Propositional speech is volitional and requires conscious mental effort in manipulating linguistic segments that have to be assembled to express meaningful ideas. Thus, propositional speech relies on language-related neural systems of controlled and intentional information processes.
Non-propositional speech (i.e. recites of series such as days of the week, months of the year, tables, and learned prayers) is automated, effortless, “ready-made”, holistic, spoken without constructed formulation, composed of invariant word sequences and highly learned responses. This language should be acquired by repetition and relies on neural pathways operating automatized information processing.
In the 19th century H. Jackson reported that many patients maintained faculties of the automatic language although the propositional speech was severely impaired. Such patients could barely complete a phrase composed of few words but they could recite the days of the week, complete sentences like “the grass is—–green“ or produce highly learned responses such as “Hi. How are you?”. H. Jackson’s observations of brain damaged patients convinced him of the existence of a dissociation (also in neural substrates), between what he called “emotional”, “inferior”, “old” or “ready-made speech” (oaths, interjections, utterances like good-bye or take care) and what it corresponds to the propositional or intellectual uses of speech.
Despite only few studies aimed at experimentally testing this assumption it is generally admitted that patients suffering from linguistic disturbances (aphasia) after cortical damage recite automatic expressions better than propositional terms. This phenomenon is known as the automatic-voluntary dissociation in aphasia.
I wonder if some authors observed ever a patient with aphasia and an inverted automatic-voluntary dissociation (automatic speech more impaired than the propositional speech). I observed only one patient in my neurologist’s career with such an inverted dissociation. This patient had a form of “conduction” aphasia.
I do not know if it is even possible to imagine to produce this inverted linguistic voluntary-automatic dissociation in healthy people with some experimental paradigm. Any idea?
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