Validating a New Measure of Subjective Stress

Abstract

This thesis aims to evaluate a new subjective measure of stress, originally developed by Lorrig, (2022), but adapted for this study. The Online Stress Assessment Tool (OSAT) aims to capture an operator’s current subjective stress level through instantaneous assessment, indicated by a single response on a scale of 0-10, where 0 indicates complete relaxation and 10 indicates maximum levels of stress. The scope of this thesis is therefore limited to assessing this measure’s convergent and discriminant validity by comparing it to existing ‘gold standard’ measurements of both subjective stress and subjective MWL. Within the experimental design, we aimed manipulate MWL and stress individually through task load (MWL) and noise (stress). An expert sample of pilots complete a 2x2 within-subjects design, completing each manipulation of stress and MWL while answering the OSAT and other stress and MWL measurements. This study limits itself to comparing results between four measurements – OSAT and the Short Stress State Questionnaire (stress measurements), ISA and the NASA-Task Load Index (MWL measurements). The structure of this thesis firstly explores the literature around stress and MWL. Secondly it explores the methodology implemented in the experiment, including tasks, equipment and measurements used. Thirdly, results from the study are reported. Finally, the discussion explores conclusions, limitations, and future directions for research.