Valence bias arises from both positive and negative responses to ambiguous stimuli

Individuals vary in their tendency to interpret emotionally ambiguous stimuli as relatively more positive or negative, a trait-like difference known as "valence bias." To date, research on valence bias has relied upon two-alternative forced-choice (2AFC) valence decisions that conflate the presence of positivity with the absence of negativity, and vice versa. This is problematic because more frequent negative judgments of ambiguous stimuli (i.e., a more negative valence bias) could represent true negative appraisals of those stimuli, or a difficulty in identifying a positive appraisal.

In two preregistered studies, participants completed a standard 2AFC valence bias task (n = 100 and n = 508 in the respective studies) and provided separate positive and negative unipolar ratings of the same stimuli.

The 2AFC valence bias task captured independent effects of both positivity and negativity. Individuals with a more negative valence bias showed high endorsement of negativity and low endorsement of positivity; those with a more positive bias showed the opposite pattern. Individuals with a more positive valence bias also exhibited a stronger relationship between positive unipolar ratings and 2AFC categorization than individuals with a more negative valence bias, suggesting a greater sensitivity to positive appraisals. These results replicated in Study 2 in a larger, more diverse sample using unique stimulus sets.

Despite individual differences as a function of valence bias, ambiguous stimuli were endorsed as both positive and negative on unipolar scales, refuting claims that they might be "valence-free." Collectively, these results demonstrated that multiple appraisals of ambiguity are recognized and weighted based on individual bias in valence processing during affective decision-making.