Memory and encoding of spoken discourse following right hemisphere damage: evidence from the Auditory Moving Window (AMW) technique

We investigated the hypotheses that impaired discourse processing following right hemisphere damage is mediated by task difficulty and is associated with deficits in discourse encoding. Spoken discourse passages differing in contextual predictability were presented to right hemisphere-damaged (RHD) patients and to non-brain-damaged (NBD) controls for subsequent recall using the Auditory Moving Window paradigm. To manipulate processing difficulty, speech segments were of normal or accelerated speech rates. The recall results showed that RHD adults recalled less than NBD controls overall and failed to recall major idea units better than minor idea units for high predictability passages presented at accelerated speech rates. Both RHD patients and NBD controls failed to recall major idea units better than minor idea units for low predictability passages, regardless of speech rate. The encoding results showed that RHD adults were both slower overall and differentially slower than NBD controls when listening to accelerated passage segments. Taken together, the encoding and recall results are consistent with the view that extracting passage gist under difficult listening conditions is especially vulnerable for patients with right hemisphere strokes.