Emotions affect human perception, which can also appear as perceived bias. When perceived
perception of size, height, face, etc. was realized, several studies have shown that conscious emotional stimuli
can cause perceptual biases. However, it has not been clarified clearly what kind of bias this perceptual bias
has produced and what direction is appeared by valence. The study wanted to determine the effect of caution
and valence by determining the size of different facial expressions after assigning attention to a particular
emotional expression. As a result, the targets of positive face were relatively wide than those of negative,
neutral face regardless of the emotion assigned to them. Moreover, the targets of positive fact were found faster
than the those of neutral face, regardless of the emotion assigned to them. These results suggest that
perceptual bias can occur based on valence rather than caution, and positive bias can occur between
positive(happy) and negative emotion(anger).