Interoceptive accuracy has been widely measured using the Heartbeat Tracking Test (HTT). We devised the novel paradigm of Interoception-Exteroception Synchronicity Judgement (IESJ) task to assess participants' interoceptive accuracy, exteroceptive accuracy, and the balancing score which reflected the ability to allocate attentions between interoceptive and exteroceptive signals. This study administered the behavioural paradigms of the HTT and the IESJ as well as other self-report scales to 119 typically-developing youths. Individuals with lower autistic traits (n = 30) showed comparable interoceptive accuracy, exteroceptive accuracy, and balancing scores as their higher autistic traits counterparts (n = 33). Taken together, the high autistic traits subgroup exhibited higher levels of alexithymia but not empathy or interoception than the low autistic traits subgroup.