Contextual Constraint Treatment for coarse coding deficit in adults with right hemisphere brain damage: Generalisation to narrative discourse comprehension

Abstract

Coarse coding is the activation of broad semantic fields that can include multiple word meanings and a variety of features, including those peripheral to a word's core meaning. It is a partially domain-general process related to general discourse comprehension and contributes to both literal and non-literal language processing. Adults with damage to the right cerebral hemisphere (RHD) and a coarse coding deficit are particularly slow to activate features of words that are relatively distant or peripheral. This manuscript reports a pre-efficacy study of Contextual Constraint Treatment (CCT), a novel, implicit treatment designed to increase the efficiency of coarse coding with the goal of improving narrative comprehension and other language performance that relies on coarse coding. Participants were four adults with RHD. The study used a single-subject controlled experimental design across subjects and behaviours. The treatment involved pre-stimulation, using a hierarchy of strong and moderately biased contexts, to prime the intended distantly related features of critical stimulus words. Three of the four participants exhibited gains in auditory narrative discourse comprehension, the primary outcome measure. All participants exhibited generalisation to untreated items. No strong generalisation to processing non-literal language was evident. The results indicate that CCT yields both improved efficiency of the coarse coding process and generalisation to narrative comprehension.

Keywords:

• Language comprehension treatment
• Language therapy
• Right hemisphere
• Brain damage
• Coarse coding

This work was supported in part by grants [DC01820] and [DC010182-01] from the National Institutes of Health (National Institute on Deafness and Other Communication Disorders) awarded to the second author.

Notes

¹Presentation level was 15 dB greater than the ambient environmental noise (per sound level meter), except when environmental noise was low. In that case, presentation level was either 65 dB (for participants with normal or corrected to normal hearing), or 80 dB (for participants with hearing loss and no hearing aid).

²Our diagnostic procedure involves assessment of both coarse coding and suppression. To date, of the 47 participants tested, 2 had only a coarse coding deficit and 17 had only a suppression deficit. An additional 14 exhibited both deficits.