The effect of mood and arousal on UCS expectancy biases

This paper reports two studies investigating the role of mood and arousal on the development of UCS expectancy biases to fear-relevant and fear-irrelevant stimuli. Experiment 1 found that, compared with a neutral control condition, individuals in both experimentally-induced positive and negative moods significantly overestimated the possibility of aversive outcomes following all types of stimuli in a hypothetical thought' conditioning experiment. Experiment 2 found that this UCS expectancy bias produced by both positive and negative mood could not be explained by the effect that these mood states might have on arousal independently of the valency of the mood. The findings appear to be explained best by emotional response categorisation theory (Psychol. Rev. 106 (1999) 337-361), which predicts that individuals would be more likely to view emotionally valenced stimuli as similar when in an emotional state. It is argued that, while negative mood may be a genuine vulnerability factor for the development of anxiety-relevant threat-outcome expectancies, the effects found with positive mood in the current studies may have less ecological relevance to real-world aetiologies.