EPG patterns in a patient with phonemic paraphasic errors

Auditorily-detected phonemic paraphasias such as substitutions are said to characterize aphasias such as Wernicke’s and conduction aphasia. However previous research has shown that the articulatory details underlying such substitutions recorded by techniques such as Electropalatography (EPG) may reveal a level of complexity not detected by the auditory analysis alone. Articulatory anomalies such as so-called Misdirected Articulatory Gestures (MAGs) may accompany the production of the substitutions and are variously perceived by listeners. A perceptual study is carried out in which 16 adult listeners rate sounds identified on the basis of EPG analysis as potential substitutions, on a scale from alveolar to velar. Some of the target sounds looked like ‘pure’ substitutions from the EPG patterns and some exhibited MAGs. Listener judgements were not always entirely predictable on the basis of EPG patterns. The occurrence of the anomalous EPG patterns (and the auditory results) is explored further in terms of a modified spreading activation model and implications for clinical management are discussed.