Do different emotional valences have same effects on spatial attention?

Emotional stimuli have a priority to be processed relative to neutral stimuli. However, it is still unclear whether different emotions have similar or distinct influences on attention. We conducted three experiments to answer the question, which used three emotion valences: positive, negative and neutral. Pictures of money, snake, lamp and letter x were used as stimuli in Experiment 1. In Experiment 2A, schematic emotional faces (angry, smile and neutral face) were used as experimental stimuli to control the stimuli complexity. In Experiment 2B, stimuli were three line drawing pictures selected from the Chinese Version of Abbreviated PAD Emotion Scales, corresponding respectively to anger, joy and neutral emotion. We employed the paradigm of inhibition of return (IOR, an effect on spatial attention that people are slow to react to stimuli which appear at recently attended locations, cf. Posner & Cohen, 1984) which used exogenous cues and included 20% catch trials. Seventy-four university students participated in the experiments. We found that participants needed more time to process negative emotional pictures (Exp1, 2A&2B), and the effect of IOR could happen at the ISI (interstimulus interval) as short as 50ms (Exp1). Meanwhile, the data demonstrated that IOR happened at 50ms ISI only when the schematic face was angry, and RTs of angry schematic faces were significantly longer than RTs of the other two faces (Exp2A). We further found that the expectancy might play a role in explaining these results (Exp3). In all three experiments, we found consistently there was a U-shaped relationship between RT and ISI, irrespective of the cue validity and emotional valence. These results showed that different emotional valences had distinct influences on attention. To be specific positive and neutral emotions could be processed more rapidly than the negative emotion.