The role of input vs. output phonological working memory in narrative production: Evidence from case series and case study approaches

ABSTRACT

Separable input and output phonological working memory (WM) capacities have been proposed, with the input capacity supporting speech recognition and the output capacity supporting production. We examined the role of input vs. output phonological WM in narrative production, examining speech rate and pronoun ratio – two measures with prior evidence of a relation to phonological WM. For speech rate, a case series approach with individuals with aphasia found no significant independent contribution of input or output phonological WM capacity after controlling for single-word production. For pronoun ratio, there was some suggestion of a role for input phonological WM. Thus, neither finding supported a specific role for an output phonological buffer in speech production. In contrast, two cases demonstrating dissociations between input and output phonological WM capacities provided suggestive evidence of predicted differences in narrative production, though follow-up research is needed. Implications for case series vs. case study approaches are discussed.

KEYWORDS:

• Working memory
• language production
• stroke
• output phonological buffer

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 Such a pattern has been demonstrated in the domain of action recognition and action production where strong correlations between these abilities were obtained at the group level whereas, at the individual level, action recognition dissociated from action production (Negri et al., 2007).

2 Computing a level above d’ = 0 that is needed to be significantly above chance is indeterminate given the number of assumptions that must be made regarding d’ distributions (Miller, 1996). If we used instead accuracy performance, 61% accuracy was required, and all participants were well above that level on both measures.

3 If a participant scored above 75% at the highest list length available (six items), linear extrapolation was used assuming chance performance (50%) on a hypothetical set of seven-item lists (e.g., 90% (18/20) at six item lists resulted in a score of 6.38 whereas 100% (20/20) resulted in a score of 6.5 giving a higher score for better performance on the final available list length). These values are an approximation made by using the simplifying assumption that all participants would have scored equivalently at the seven-item list length. This method was used for five participants on the digit matching task. No participants required extrapolation for category probe, rhyme probe, or nonword probe.

4 For a much larger sample of age-matched controls (N = 59; Zahn, 2024), SS’s speech rate (112 wpm) fell within their range (88–185). LB’s speech rate (72 wpm) was still significantly below that of controls (t(59) = –2.84, p = .006).

Additional information

Funding

This work was supported by the T. L. L. Temple Foundation Neuroplasticity Lab award to Rice University.