Visual analog scales for assessment of thermal perception in different environments.

Introduction: Subjective thermal perception in stable and dynamic environments has been measured primarily by categorical rating scales. At present, there is an increasing use of visual analog scales (VAS) to assess whole body and body region thermal perceptions in laboratory and other thermal environments. Discussion: The rationale behind the use of VAS is that individuals are more accurate in conveying their subjective experience if they are not forced to make ratings according to numbers or categories. Unipolar scales have the advantage of focusing on a single subjective perception, such as the amount of cold the subject experiences. With bipolar scales (e.g., cold to hot), the sensitivity in measuring the extent of a specific thermal experience may be diminished because the subject needs to make a discontinuous change from one thermal perception to another. Conclusions: The robust psychometric properties of VAS indicate their usefulness in measuring thermal experience. Uni-polar VAS with a large equal interval scoring range will enable the investigator to measure small gradients of change in perceptual experience. However, the subjective perception of thermal status is not highly accurate at thermal extremes, and caution is needed in sole reliance on subjective report in these conditions.