Effects of Head Inclination and Focal Length on Emotional State and Degree of Stress1

Abstract

Although previous studies have investigated the effect of head inclination on one's psychological state, such as their emotionality, there is still confusion related to the association between head inclination and focal length. Therefore, the current study examined the effects of both head inclination and focal length on an individual's emotional state and degree of stress, which were both controlled individually, and then clarified these independent and interactive effects. Twenty adults participated in all combinations of two focal-length conditions (long or short) and two head-inclination conditions (upward or downward) consecutively. The participants' saliva was then examined to determine α-amylase levels and assess their physiological states; to assess emotional states after each condition, participants were required to complete several self-report questionnaires. Two-way analyses of variance were conducted, and the results showed that focal length exerted significant effects on their psychological states, but the effect of head inclination on the psychological state was only partially significant. The findings imply that focal length, rather than head inclination, primarily affected psychological states. It is noteworthy that previous studies' results regarding the effect of head inclination on emotional states may have mistakenly indicated a relationship because focal length coincides with head inclination.