Mehdi Bakhtiar

The University of Hong Kong | HKU · Faculty of Education

The problem in language comprehension in people with right hemisphere damage (RHD) is more equivocal than people with left hemisphere damage. This study explores the reading and listening comprehension of Cantonese-speaking individuals with RHD, left hemisphere damage, and neurotypical healthy controls using the Cantonese Computerized Revised Token...

Introduction: Behavioral and questionnaire-based studies suggest that children who stutter (CWS) exhibit poorer response inhibition than children who do not stutter (CWNS). However, the behavioral findings in adults who stutter (AWS) are less unequivocal and mainly based on manual response inhibition. Further study is therefore needed, especially...

Purpose Evidence increasingly indicates that people with developmental stuttering have auditory perception deficits. Our previous research has indicated similar but slower performance in categorical perception of the speech sounds under the quiet condition in children who stutter and adults who stutter (AWS) compared with their typically fluent cou...

The purpose of this study was to establish psycholinguistic norms for 249 action pictures in Cantonese, a language with few norms available. We provide normative data for rated visual complexity, rated age of acquisition, name agreement, word frequency and rated familiarity in this study. Forty participants were recruited to participate in both tim...

A question under debate in psycholinguistics is the nature of the relationship between spoken and written languages. Although it has been extensively shown that orthographic transparency, which varies across writing systems, strongly affects reading performance, its role in speech processing is much less investigated. The present study addressed th...

The acquisition of an alphabetic orthography transforms speech processing in the human brain. Behavioral evidence shows that phonological awareness as assessed by meta-phonological tasks like phoneme judgment, is enhanced by alphabetic literacy acquisition. The current study investigates the time-course of the neuro-cognitive operations underlying...

Picture-naming latency differs across languages in bilingual speakers. We compared the effects of key psycholinguistic variables on picture naming among two groups of Chinese bilingual speakers and Mandarin monolingual speakers. First, we asked bilingual and monolingual speakers to estimate the age of acquisition, familiarity, visual complexity, na...

Purpose: This study reports the psychometric development of the Cantonese versions of the English Computerized Revised Token Test (CRTT) for persons with aphasia (PWAs) and healthy controls (HCs). Method: The English CRTT was translated into standard Chinese for the Reading–Word Fade version (CRTT-R-WF- Cantonese) and into formal Cantonese for the...

Stuttering is often attributed to the impaired speech production system, however, there is growing evidence implicating issues in speech perception. Our previous research showed that children who stutter have similar patterns but slower categorical perception (i.e. the ability to categorise different acoustic variations of the speech sounds into th...

There have been controversial debates across multiple disciplines regarding the underlying mechanism of developmental stuttering. Stuttering is often related to issues in the speech production system; however, the presence and extent of a speech perception deficit is less clear. This study aimed to investigate the speech perception of children who...

The individual data points for d' scores in the CWS and CWNS groups. (XLSX)

The individual data points for boundary position and width in the CWS and CWNS groups. (XLSX)

Background: Individuals with aphasia can be impaired in action and object naming and most typically are more impaired when naming actions than objects. However, it is not clear if effects of grammatical class are language-general as assumed by some theories of speech production. Aims: We predicted greater impairments to action than object naming in...

The effect of Age of Acquisition (AoA) on visual word recognition is remarkable. However, there is debate about the loci of AoA effects. The Arbitrary Mapping hypothesis assumes AoA reflects mappings between input (e.g. orthography) and output (e.g. phonology) formed during the acquisition of literacy. An alternative view is that AoA reflects the a...

Current models of oral reading assume that different routes (sublexical, lexical, and semantic) mediate oral reading performance and reliance on different routes during oral reading depends on the characteristics of print to sound mappings. Studies of single cases of acquired dyslexia in aphasia have contributed to the development of such models by...

The age of acquisition (AoA) of a word has an effect on skilled reading performance. According to the arbitrary-mapping (AM) hypothesis, AoA effects on word naming are a consequence of arbitrary mappings between input and output in the lexical network. The AM hypothesis predicts that effects of AoA will be observed when words have unpredictable ort...

This article features contributions of 15 young and experienced researchers and clinicians from 12 countries from Africa, Asia, Eastern Europe, the Middle East, South America, and North America. The growing fascination with cluttering continues to spread around the world, in a spirit of being open-minded to the ideas of colleagues from different cu...

Studies of patients with aphasia have found dissociations in their ability to read words and name pictures (Hillis & Caramazza, 1995; Hillis & Caramazza, 1991). Persian orthography is characterised by nearly regular orthography-phonology (OP) mappings however, the omission of some vowels in the script makes the OP mapping of many words less predict...

In this study, we report normative data by native Persian speakers for concept familiarity, age of acquisition (AoA), imageability, image agreement, name agreement, and visual complexity, as well as values for word frequency, word length, and naming latency for 200 of the colored Snodgrass and Vanderwart (Journal of Experimental Psychology: Human L...

The present study was conducted to investigate the dissociation between some linguistic variables including the Mean Length of Utterance (MLU) and Type Token Ratio (TTR) and stuttering severity in both languages of Kurdish-Persian bilingual people who stutter (PWS). The connected speech of 31 PWS (age ranges: 9 to 13 years old) speaking in their fi...

Karimi, Nilipour, Shafiei and Howell have raised some issues in regards to a study of which we were authors (Bakhtiar, Seifpanahi, Hossein, Ghanadzade & Packman, 2010). In that study, we reported the translation of the Stuttering Severity Instrument-3 (SSI-3) into Persian and reported its reliability when used with 12 Persian speaking preschool chi...

Previous studies have indicated significant differences in vocal parameters between children with Down syndrome and normal children. This study was performed to see whether there is a significant dissociation between normal adults and adults with Down syndrome in terms of some vocal parameters. The participants were 22 adults with Down syndrome and...

Unlabelled: There is a pressing need in Iran for the translation of widely used speech-language assessment tools into Persian. This study reports the interjudge and intrajudge reliability of a Persian translation of the Stuttering Severity Instrument-3 (SSI-3) (Riley, 1994). There was greater than 80% interjudge and intrajudge agreement on scale s...

In this study, the immediate and extended effects of the Lidcombe Program were investigated for the first time in Iran. Treatment in the Lidcombe Program is carried out by the child's parent (or carer) in the child's everyday environment. The program has been shown to be effective with preschool children who stutter (i.e. younger than 6 years) and...

Objectives: Objective measurements in general and acoustic measurements in particular have become a substantial aspect of voice assessment during the last few decades and studies have established that normative data is necessary for acoustic analysis. Voice acoustic analysis including fundamental frequency (F(0)), jitter, shimmer, harmonics-to-noi...

CONTEXT AND OBJECTIVE: Stuttering is a complex disease that influences occupational, social, academic and emotional achievements. The aim of this study was to correlate the stuttering severity index with speaking rates of mothers and children. DESIGN AND SETTING: Cross-sectional study, at the child rehabilitation clinics of Tehran city. METHODS: 35...

Although speech motor control has been studied intensively in normal-hearing and hearing-impaired (HI) speakers in America and Europe, essentially no research has been performed using Persian-speaking participants. A total of 46 prelingual hearing-impaired 15-18-year-old males and 15 normally hearing control participants from Iran participated in t...

Stuttering has a life span incidence and it significantly impacts academic, social, emotional and vocational achievements of patients who stutter. The purpose of the present study was to examine phonological encoding in young children who stutter (CWS) during a non word repetition task and to test the covert repair hypothesis (CRH) and phonological...