Role of Ethnicity and Environment on Regulation of Response Towards Sensory Stimulation in Children

Heart rate variability (HRV) has been considered as a promising marker for autonomic activity, specifically of parasympathetic nervous system (PNS) activity (Task Force of the European Society of Cardiology and the North American Society for Pacing and Electrophysiology, 1996). Frequency domain analysis covers total power (0.0-0.5 Hz) in its raw and normalized units, low (LF; 0.04-0.15 Hz) and high (HF; 0.15-0.40 Hz) frequency components in its raw and normalized units. The normalized units of the LF will be used as representative of predominantly sympathetic modulation activity (SNS), while the normalized units of the HF will be used as representatives of parasympathetic modulation activity.

Since HRV can measure both SNS and PNS simultaneously, this study will use HRV as one of the measurements. Nevertheless, it has been argued if the value of LF is a pure measure of SNS (Goldstein et al., 2011). Therefore, other than HRV, EDA will also be a supplementary measurement.

Electrodermal activity (EDA) is a valid measure of autonomic nervous system activity frequently used to index behavioural processes (Boucsein, Fowles, Grimnes, Ben-Shakhar & Roth, 2012). EDA is composed of a tonic and phasic drivers that reflect autonomic availability and response patterns respectively. Tonic EDA will be represented by the CDA.Tonic, which has been recommended to be the most accurate representation of the deconvoluted underlying skin conductance level within the specified block expressed in µS (Benedek & Kaernbach, 2010). To represent the sympathetic activity in the form of phasic skin conductance response, the CDA.SCR will computed. The CDA.SCR is considered as the average phasic driver within the specified response window initially set, and represents the phasic EDA most accurately expressed in units of µS (Benedek & Kaernbach, 2010).

To measure the child's behavioural patterns in response to sensory stimulus in his daily activities, we will use the original Sensory Profile (Dunn, 1999) and Chinese Sensory Profile (Cheung & Siu, 2010). The original Sensory Profile which was developed and validated by Dunn (1999) is a 125 item questionnaire that is completed by the caregiver. The Chinese Sensory Profile was translated and validated by Cheung and Siu (2010) is a 100-item parent-report measure used among children and uses the same rating scale as with the original one. In this research, similar items from the original English version and Chinese versions of the Sensory Profile are identified and matched.

Temperament will be measured using the Temperament in Middle Childhood Questionnaire (TMCQ; Simonds & Rothbart, 2004; 2006) for 7-10 year old children; and the Early Adolescent Temperament Questionnaire (TMCQ; Ellis & Rothbart, 2001) for children 11-12 years old. TMCQ is a 157-item parent questionnaire, while EATQ s 65-item form with a scale; both are parent-rated measures of reactive and regulative temperament traits among children using a 5-point Likert scale (a range of "Almost always untrue-1" to "Almost always true-5") for each item. The original version was developed using the English language. The Chinese translation of TMCQ (Lay et al., 2004) and EATQ (Lay & Hsu, 2004) will be used Chinese-speaking participants.

The Child and Youth Resilience Measure [37] (CYRM) was established through a process of interviews with youth and adults in countries around the world was completed by the participants' parents. This research uses the 28-item (> 10 yrs. old) or 26 item (5-9 yrs. old) Person-Most-Knowledgeable questionnaire version, which was developed and validated by Ungar and Liebenberg [38]. While the CYRM is originally in English, a translated Chinese version was recommended and provided by the authors and was used among Chinese participants in this research. Parents rate each item with three possible response: "Yes," "Sometimes" or "No."

Body mass index (BMI) was ascertained through measurement of the participants' height (cm) and weight (kg).