Misunderstandings of the Hickok & Poeppel Dual Stream framework: Comments on Dial & Martin 2017

A recent paper by Dial& Martin (DM) presents some interesting data on the relation between performance on a range of different speech perception tasks including some that have been the topic of discussion on this blog and in many of my papers. These include syllable discrimination and auditory comprehension among others. I have argued in several papers with David Poeppel and others that these two tasks differentially engage the dorsal (syllable discrimination) and ventral streams (comprehension). DM sought to test this claim by testing how well these tasks hang together or dissociate in a group of 13 aphasic patients. Their primary claim is that performance on sublexical and comprehension tasks largely hang together in contrast to previous reports of double dissociations. They suggest the discrepancy is due to better controlled stimuli in their experiment compared to past studies. DM's experiments are really nicely done and generated some fantastic data. I don't think their conclusions about the dual stream model follow, however, because they get the dual stream model wrong.First a comment on their data, focusing on the syllable discrimination and word picture matching tasks (their Experiment 2a) as these are the poster-child cases. DM report a strong correlation between performance on these tasks. It indeed looks quite strong. But they also report that two patients (18%) performed significantly better on the auditory comprehen...
Source: Talking Brains - Category: Neuroscience Authors: Source Type: blogs