Facial feedback hypothesis

The hypothesis that feedback arising from facial activity contributes to felt emotion. Weak versions predict modulation; stronger versions predict initiation, category-specific effects or necessity. These claims require different experimental tests.

Let $X$ be randomized assignment, $F$ facial activity, $M$ sensory feedback and $Y$ a report. One possible model is $F=X$, $M=F$, $Y=M$. A second is $F=X$, $M=F$, $D=X$, $Y=D$, where $D$ is an expectancy route. Both models predict the same observed $X,F,Y$ even though intervening on $M$ changes $Y$ only in the first. Therefore randomizing $X$ and measuring $F,Y$ does not distinguish these mechanisms. Identifying causal mediation requires further assumptions or interventions. The binary models are a logical counterexample, not participant data.

The 1988 experiment associated with Fritz Strack used different ways of holding a pen to facilitate or inhibit facial activity associated with smiling. The manipulation was intended to avoid explicitly asking participants to act happy. Its interpretive importance lies in separating bodily feedback from explicit labeling; its limitation is that different postures can also change effort and task experience.^[ref]

Information about facial activity available to the organism, including bodily sensory consequences and information used in interpreting its own state. A manipulation of facial movement can change several other things as well; its total effect on a report does not uniquely identify this route.