Complex response inhibition and cognitive flexibility in school-aged Cypriot-Greek-speaking children who stutter

Inhibitory Control, Cognitive Flexibility, and the Production of Disfluencies in Children Who Do and Do Not Stutter

PURPOSE

Differences in inhibitory control and cognitive flexibility between children who stutter (CWS) and children who do not stutter (CWNS) have been previously demonstrated. The aim of the current study was to investigate whether the previously reported inhibitory control- and cognitive flexibility-related performance costs for CWS are associated with the number of speech disfluencies that they produce.

METHOD

Participants were 19 CWS (Mage = 7.58 years, range: 6.08-9.17) and 19 CWNS matched on age and gender (Mage = 7.58 years, range: 6.08-9.33). Gamma regression models were used to investigate possible associations between performance costs in speed and accuracy measured during a computer task evaluating inhibitory control and cognitive flexibility and the number of speech disfluencies during video-recorded speech samples (story retelling and casual conversation).

RESULTS

Two significant interactions were observed. For both inhibitory control and cognitive flexibility, we identified a significant group and inhibitory control/cognitive flexibility performance-cost interaction in stuttering-like disfluencies (SLDs), indicating that the performance-cost effects on SLD production were significantly higher in the CWS group, compared to the CWNS group.

CONCLUSIONS

CWS with reduced inhibitory control or cognitive flexibility produce more SLDs, but not other disfluencies. These results are partly in line with some previous findings in nonstuttering and stuttering populations linking inhibitory control and cognitive flexibility weaknesses to the production of speech disfluencies.

Cognitive flexibility in younger and older children who stutter

Purpose

Recent research findings suggest possible weaknesses in cognitive flexibility (CF) in children who stutter (CWS) when compared to children who do not stutter (CWNS). Studies so far, have been conducted with either younger (3-6 years old) or older children (6-12 years old) with a variety of measures. The purpose of the present study was to investigate CF with the use of a single behavioral measure across a broader age range (4-10 years old).

Methods

Participants were 37 CWS (mean age = 6.90 years) and 37 age-and gender-matched CWNS (mean age = 6.88 years), divided in a younger (below 7 years) and older (above 7 years) age group. All participants undertook a computerized visual set-shifting task consisting of three blocks. CF was evaluated through across-and within-block comparisons of the actual response speed and accuracy values. In addition, mixing-and set-shifting-costs were evaluated based on the mean response speed and accuracy.

Results

All participants showed expected mixing-and set-shifting-costs. Only the within-block analyses yielded significant between (sub)group differences. Investigation of the block × classification group × age group interactions showed that older CWS had larger set-shifting-costs (slowed down more and made more errors) compared to older CWNS.

Conclusion

While all participants required more time during set-shifting trials, only the older CWS (7-10 years old), and not younger CWS, were slower and made more errors. This finding corroborates previous findings in CWS of a similar age and could possibly point to a role of CF in stuttering persistence.