Measurement error masks bipolarity in affect ratings.

For years, affect researchers have debated about the true dimensionality of mood. Some have argued that positive and negative moods are largely independent and can be experienced simultaneously. Others claim that mood is bipolar, that joy and sorrow represent opposite ends of a single dimension. The 3 studies presented in this article suggest that the evidence that purportedly shows the independence of seemingly opposite mood states, that is, low correlations between positive and negative moods, may be the result of failures to consider biases due to random and nonrandom response error. When these sources of error are taken into account using multiple methods of mood assessment, a largely bipolar structure for affect emerges. The data herein speak to the importance of a multi-method approach to the measurement of mood.