title: The impact of threat and cognitive stress on speech motor control in people who stutter.
abstract: OBJECTIVE
  In the present study, an Emotional Stroop and Classical Stroop task were used to separate the effect of threat content and cognitive stress from the phonetic features of words on motor preparation and execution processes.
  
  
  METHODS
  A group of 10 people who stutter (PWS) and 10 matched people who do not stutter (PNS) repeated colour names for threat content words and neutral words, as well as for traditional Stroop stimuli. Data collection included speech acoustics and movement data from upper lip and lower lip using 3D EMA.
  
  
  RESULTS
  PWS in both tasks were slower to respond and showed smaller upper lip movement ranges than PNS. For the Emotional Stroop task only, PWS were found to show larger inter-lip phase differences compared to PNS. General threat words were executed with faster lower lip movements (larger range and shorter duration) in both groups, but only PWS showed a change in upper lip movements. For stutter specific threat words, both groups showed a more variable lip coordination pattern, but only PWS showed a delay in reaction time compared to neutral words. Individual stuttered words showed no effects. Both groups showed a classical Stroop interference effect in reaction time but no changes in motor variables.
  
  
  CONCLUSIONS
  This study shows differential motor responses in PWS compared to controls for specific threat words. Cognitive stress was not found to affect stuttering individuals differently than controls or that its impact spreads to motor execution processes.
  
  
  OBJECTIVE
  After reading this article, the reader will be able to: (1) discuss the importance of understanding how threat content influences speech motor control in people who stutter and non-stuttering speakers; (2) discuss the need to use tasks like the Emotional Stroop and Regular Stroop to separate phonetic (word-bound) based impact on fluency from other factors in people who stutter; and (3) describe the role of anxiety and cognitive stress on speech motor processes.
authors.affiliation: University of Toronto, Speech-Language Pathology, Oral Dynamics Lab (ODL), Canada; Department of Psychology, Canada; Institute of Biomaterials and Biomedical Engineering, Canada; Graduate Department of Rehabilitation Science, Canada; Toronto Rehabilitation Institute, Canada. Electronic address: p.vanlieshout@utoronto.ca.
authors.forename: Pascal van
authors.initials: Pv
authors.lastname: Lieshout
authors.affiliation: University of Toronto, Speech-Language Pathology, Oral Dynamics Lab (ODL), Canada; Department of Psychology, Canada; Toronto Rehabilitation Institute, Canada; Interdisciplinary Center (IDC) Herzliya, School of Psychology, Communication, Aging and Neuropsychology Lab (CANlab), Israel.
authors.forename: Boaz
authors.initials: B
authors.lastname: Ben-David
authors.affiliation: University of Toronto, Speech-Language Pathology, Oral Dynamics Lab (ODL), Canada.
authors.forename: Melinda
authors.initials: M
authors.lastname: Lipski
authors.affiliation: University of Toronto, Speech-Language Pathology, Oral Dynamics Lab (ODL), Canada.
authors.forename: Aravind
authors.initials: A
authors.lastname: Namasivayam
mesh_terms: D000328:Adult; D001007:Anxiety / Q000503:physiopathology; D016022:Case-Control Studies; D003071:Cognition / Q000502:physiology; D005260:Female; D006801:Humans; D007802:Language; D008046:Lip / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009048:Motor Skills; D010700:Phonetics; D011597:Psychomotor Performance; D011930:Reaction Time; D013060:Speech / Q000502:physiology*; D013061:Speech Acoustics; D013068:Speech Production Measurement / Q000379:methods; D013315:Stress, Psychological / Q000503:physiopathology*; D057190:Stroop Test; D013342:Stuttering / Q000503:physiopathology / Q000523:psychology*; D013997:Time Factors; D055815:Young Adult
keywords: Anxiety; Classical Stroop; Emotional Stroop; Kinematics; Stuttering