Thermal perception and ethnicity: a British and Chinese comparison
Creators: name: Lawes, Micheala
Publisher: name: Loughborough University
Year: 2023
Subjects: Design not elsewhere classified

description: People from diverse ethnic groups or geographical climates may experience different thermal sensations in the same environment (Nakano et al. 2002). Some studies have demonstrated ethnic differences in preferred air temperatures and perception of the thermal environment (Nakano et al. 2002; Knez and Thorsson 2006; Havenith et al. 2020); others report no differences (Watson et al. 2005; Kurazumi et al. 2016). Physiological and psychological differences between ethnicities could influence how people interpret the thermal environment (Brager and De Dear 1998; Taylor 2006), with variations occurring genetically (Long and Kittles 2003; Bamshad et al. 2004), phenotypically (Taylor 2006), as well as through cultural and societal factors (Knez and Thorsson 2008; Xiong et al. 2019; He et al. 2020). Physiologically, humans sense the thermal environment via thermoreceptors, specialised nerve fibres in the skin (Kashio and Tominaga 2022). Thermal information is transmitted to the brain information through an afferent process. Little is known whether the encoding of external temperature stimuli differs between ethnic populations. Therefore, this research aimed to investigate ethnicity's influence on thermal perception between body-matched white British and Chinese participants and the extent to which physiological or psychological factors drive any variations observed. Four empirical studies were performed to investigate ethnic differences in local thermal sensation to warm (40°C) and cool (20°C) conductive stimuli (Chapter 3), the comparison between conductive and convective thermal stimuli on local thermal sensation (Chapter 4), ethnic differences in cutaneous thermal threshold detection (Chapter 5) and lastly, an exploration of ethnic differences in whole-body thermal perception at various relative humidities (Chapter 6). Several key themes emerged from the research: (1) No ethnic differences were found in the somatosensory response to warm and cool thermal stimuli. (2) Ethnic differences arise in the interpretation of ‘hot’ and ‘cold’ sensations. The Chinese group had a narrower inter-threshold range between hot and cold cutaneous sensations than the British group. (3) Minor ethnic differences were observed in whole-body perceptual data for thermal sensation and thermal comfort. However, when exposed to various relative humidity levels, significant differences emerged in perceptions of wetness and stickiness. (4) Conductive and convective thermal sensation measurements can vary significantly between a stimulus application time of 0 seconds (to provide an immediate response) and durations of 10, 30 and 60 seconds. Local skin temperature and thermal sensation stabilise at 30-s for the conductive response and 60-s for the convective. Across all studies, no significant differences were identified across most physiological measurements (e.g., forearm blood flow, resting metabolic rate, heart rate, tympanic temperature, or mean skin temperature), with minor differences observed in anthropometrics, skin thickness and skin hydration. Overall, the research assessed physiological and perceptual ethnic differences between white British and Chinese populations. The results show that both groups have the same somatosensory response to the thermal environment, yet the interpretation of the thermal information is likely shaped by non-physiological factors such as thermal history, experiences, and expectations.