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Effects of speech rate on phonological sequencing errors in aphasia
Brain and Language 103 (2007) 8–249 www.elsevier.com/locate/b&l
Effects of speech rate on phonological sequencing errors in aphasia Tepanta R.D. Fossett *, Malcolm R. McNeil Department of Communication Science and Disorders, University of Pittsburgh, 4033 Forbes Avenue, Pittsburgh, PA 15260, USA VA Pittsburgh Healthcare System, Pittsburgh, PA 15240, USA
Introduction Sound production errors may be generated at different levels of the linguistic and motor systems. However, phonetically well-formed serial order errors have been proposed to be differentially diagnostic—adding to the separation of phonological encoding-level errors from motor planning and programming-level errors (McNeil, Robin, & Schmidt, 1997). Their presence, and the conditions under which they are elicited, therefore, have clinical as well as theoretical importance. The models of Dell and colleagues (Dell, 1986; Dell, Burger, & Svec, 1997) propose that time limitations on phonological encoding (PE), as realized through the manipulation of speaking rate, will affect the relative proportion of serial order soundlevel errors (anticipations, perseverations, exchanges). Specifically, the model predicts that with increased speech rate there will be a decrease in both the anticipation to perseveration error ratio and anticipation to exchange ratio. Dell and colleagues have extended their predictions about the effects of speaking rate on PE to persons with aphasia (PWA). While supported by connectionist modeling, the rate-specific predictions of Dell and colleagues have been subjected to little experimental verification from PWA. This study sought to evaluate these serial order error predictions in carefully selected non-brain damaged NBD participants and in PWA that were without concomitant motor speech impairments. Methods and procedures Participants Participants were sixteen older NBD adults and 16 PWA, but no concomitant motor speech disorders. Participants ranged in age from 36 to 77 years. PWA met the definition of McNeil and Pratt (2001) and produced phonological paraphasias. All participants met group specific criteria on a large battery of cognitive-linguistic and motor screening measures.
ler stimuli were presented, but only target stimuli were cued for production by presentation of a tone. Inter-stimulus presentation rate was controlled to allow for variability in production times. Stimuli were randomized and rate conditions counterbalanced to control for order effects. Data were analyzed using a repeated measures design. All productions were transcribed with broad phonetic transcription. Perceptually identified errors were transcribed narrowly. Vocal reaction and total utterance duration were measured. Extensive data inclusion criteria (e.g., production were required to include the same number of syllables as the stimulus) and coding rules were developed. Errors were primarily characterized as serial order errors (anticipations, exchanges, perseverations) or distortion errors. Distortion errors were examined to account for sound errors assumed to be generated at the motor level of the production system. An alpha of p 6 .05 was set for all tests. Results Two, two-way repeated measure ANOVAs were computed to examine the effects of speaking rate on the anticipation to exchange and anticipation to perseveration serial order error ratios. Results for the anticipation/ exchange error ratio revealed non-significant main effects for rate (F2,46 = 1.727, p = .19, g2 = .070), and group (F1,23 = .907, p = .35, g2 = .04) and a non-significant interaction (F2,46 = .329, p = .72, g2 = .01). Results for the anticipation/perseveration ratio revealed a non-significant main effect for group (F1,23 = .512, p = .48, g2 = .02), a significant main effect for rate (F2,46 = 4.773, p = .01, g2 = .17) and a non-significant interaction (F2,46 = 1.477, p = .24, g2 = .06). Significantly more anticipation, relative to perseveration errors occurred for both groups across the three speech rates. Results for the percentage of distortion errors revealed a non-significant main effect of rate (F2,58 = .217, p = .81, g2 = .01) and group (F1,29 = .974, p = .33, g2 = .03), and a non-significant interaction (F2,58 = .037, p = .96, g2 = .00).
Procedures Discussion and conclusions Participants were asked to repeat auditorily presented phonologically challenging sentences at three target speaking rates. A direct magnitude production procedure was used to elicit rate changes and rate manipulation was relative to each participant’s own typical speaking rate. Target and fil*
Corresponding author. E-mail address: [email protected] (T.R.D. Fossett).
doi:10.1016/j.bandl.2007.07.073
This study provided support for the theoretical perspective that phonological processing may be affected by time limitations, specifically, those imposed by speaking rate. However, results of this study provided evidence counter to the direction proposed in the predictions from the Dell (1986) and Dell et al. (1997) models. That is, there was a significant effect of rate on A:P errors for both groups, however, the ratio increased with increasing speaking rate and the change was due to a greater magnitude
Abstract / Brain and Language 103 (2007) 8–249 of change in the proportion of anticipation errors rather than an increase in perseveration errors as the model predicts. Results for the other nonsignificant serial order error ratios were uninterpretable due to low statistical power. Due to task difficulty, few stimuli met the criteria for inclusion, thus substantively reducing statistical power and making the nonsignificant results uninterpretable. References Dell, G. (1986). A spreading-activation theory of retrieval in sentence production. Psychological Review, 93, 283–321.
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Dell, G. S., Burger, L. K., & Svec, W. R. (1997). Language production and serial order: A functional analysis and a model. Psychological Review, 104, 123–147. McNeil, M. R., & Pratt, S. R. (2001). Defining aphasia: Some theoretical and clinical implications of operating from a formal definition. Aphasiology, 15, 901–911. McNeil, M. R., Robin, D. A., & Schmidt, R. A. (1997). Apraxia of speech: Definition, differentiation, and treatment. In M. R. McNeil (Ed.), Clinical management of sensorimotor speech disorders (pp. 311–344). NY: Thieme Medical Publishers.
Effects of speech rate on phonological sequencing errors in aphasia Tepanta R.D. Fossett *, Malcolm R. McNeil Department of Communication Science and Disorders, University of Pittsburgh, 4033 Forbes Avenue, Pittsburgh, PA 15260, USA VA Pittsburgh Healthcare System, Pittsburgh, PA 15240, USA
Introduction Sound production errors may be generated at different levels of the linguistic and motor systems. However, phonetically well-formed serial order errors have been proposed to be differentially diagnostic—adding to the separation of phonological encoding-level errors from motor planning and programming-level errors (McNeil, Robin, & Schmidt, 1997). Their presence, and the conditions under which they are elicited, therefore, have clinical as well as theoretical importance. The models of Dell and colleagues (Dell, 1986; Dell, Burger, & Svec, 1997) propose that time limitations on phonological encoding (PE), as realized through the manipulation of speaking rate, will affect the relative proportion of serial order soundlevel errors (anticipations, perseverations, exchanges). Specifically, the model predicts that with increased speech rate there will be a decrease in both the anticipation to perseveration error ratio and anticipation to exchange ratio. Dell and colleagues have extended their predictions about the effects of speaking rate on PE to persons with aphasia (PWA). While supported by connectionist modeling, the rate-specific predictions of Dell and colleagues have been subjected to little experimental verification from PWA. This study sought to evaluate these serial order error predictions in carefully selected non-brain damaged NBD participants and in PWA that were without concomitant motor speech impairments. Methods and procedures Participants Participants were sixteen older NBD adults and 16 PWA, but no concomitant motor speech disorders. Participants ranged in age from 36 to 77 years. PWA met the definition of McNeil and Pratt (2001) and produced phonological paraphasias. All participants met group specific criteria on a large battery of cognitive-linguistic and motor screening measures.
ler stimuli were presented, but only target stimuli were cued for production by presentation of a tone. Inter-stimulus presentation rate was controlled to allow for variability in production times. Stimuli were randomized and rate conditions counterbalanced to control for order effects. Data were analyzed using a repeated measures design. All productions were transcribed with broad phonetic transcription. Perceptually identified errors were transcribed narrowly. Vocal reaction and total utterance duration were measured. Extensive data inclusion criteria (e.g., production were required to include the same number of syllables as the stimulus) and coding rules were developed. Errors were primarily characterized as serial order errors (anticipations, exchanges, perseverations) or distortion errors. Distortion errors were examined to account for sound errors assumed to be generated at the motor level of the production system. An alpha of p 6 .05 was set for all tests. Results Two, two-way repeated measure ANOVAs were computed to examine the effects of speaking rate on the anticipation to exchange and anticipation to perseveration serial order error ratios. Results for the anticipation/ exchange error ratio revealed non-significant main effects for rate (F2,46 = 1.727, p = .19, g2 = .070), and group (F1,23 = .907, p = .35, g2 = .04) and a non-significant interaction (F2,46 = .329, p = .72, g2 = .01). Results for the anticipation/perseveration ratio revealed a non-significant main effect for group (F1,23 = .512, p = .48, g2 = .02), a significant main effect for rate (F2,46 = 4.773, p = .01, g2 = .17) and a non-significant interaction (F2,46 = 1.477, p = .24, g2 = .06). Significantly more anticipation, relative to perseveration errors occurred for both groups across the three speech rates. Results for the percentage of distortion errors revealed a non-significant main effect of rate (F2,58 = .217, p = .81, g2 = .01) and group (F1,29 = .974, p = .33, g2 = .03), and a non-significant interaction (F2,58 = .037, p = .96, g2 = .00).
Procedures Discussion and conclusions Participants were asked to repeat auditorily presented phonologically challenging sentences at three target speaking rates. A direct magnitude production procedure was used to elicit rate changes and rate manipulation was relative to each participant’s own typical speaking rate. Target and fil*
Corresponding author. E-mail address: [email protected] (T.R.D. Fossett).
doi:10.1016/j.bandl.2007.07.073
This study provided support for the theoretical perspective that phonological processing may be affected by time limitations, specifically, those imposed by speaking rate. However, results of this study provided evidence counter to the direction proposed in the predictions from the Dell (1986) and Dell et al. (1997) models. That is, there was a significant effect of rate on A:P errors for both groups, however, the ratio increased with increasing speaking rate and the change was due to a greater magnitude
Abstract / Brain and Language 103 (2007) 8–249 of change in the proportion of anticipation errors rather than an increase in perseveration errors as the model predicts. Results for the other nonsignificant serial order error ratios were uninterpretable due to low statistical power. Due to task difficulty, few stimuli met the criteria for inclusion, thus substantively reducing statistical power and making the nonsignificant results uninterpretable. References Dell, G. (1986). A spreading-activation theory of retrieval in sentence production. Psychological Review, 93, 283–321.
119
Dell, G. S., Burger, L. K., & Svec, W. R. (1997). Language production and serial order: A functional analysis and a model. Psychological Review, 104, 123–147. McNeil, M. R., & Pratt, S. R. (2001). Defining aphasia: Some theoretical and clinical implications of operating from a formal definition. Aphasiology, 15, 901–911. McNeil, M. R., Robin, D. A., & Schmidt, R. A. (1997). Apraxia of speech: Definition, differentiation, and treatment. In M. R. McNeil (Ed.), Clinical management of sensorimotor speech disorders (pp. 311–344). NY: Thieme Medical Publishers.