In the cognitive approach to the study of meaning, conceptual metonymy is defined as follows:

“Metonymy is a cognitive process in which one conceptual entity, the vehicle, provides mental access to another conceptual entity, the target, within the same idealized cognitive model” (Kövecses and Radden, 1998: 39).

In this approach, metonymy is not merely a rhetorical or aesthetic device; it is a feature of concepts, not just words. Metonymy is used in everyday life by ordinary people without requiring conscious effort. In other words, the system of conceptual metonymies, much like our linguistic and other conceptual systems, is unconscious and automatic, operating without significant cognitive effort. Metonymy has an experiential basis. For instance, the PART FOR WHOLE metonymy stems from our experiences of how different components of a phenomenon relate to its entirety. Ultimately, like metaphor, metonymy is not just a linguistic tool for expressing thought; rather, thought and the mind itself are inherently metonymic in nature (Lakoff and Johnson, 1980).

Kövecses (2004) conceptualizes emotions as a five-stage cognitive model:

1. Cause of emotion
2. Emotion
3. Attempt at control
4. Loss of control
5. Response

He explains this cognitive model as follows: An individual is emotionally calm. Suddenly, an external event occurs, causing a disturbance. This event has a profound impact on the individual. At this moment, the emotion is triggered. The individual becomes agitated. Their heart rate and body temperature increase, and their facial color changes. The individual's experience of this emotion is initially dominated by internal physical effects. Within the emotion, there is an impulse that compels the individual to perform an action. The individual knows that this action is dangerous and could cause physical or psychological harm to themselves or others. Therefore, they make a great effort to resist the force of the emotion. However, the force of the emotion is greater than their own, causing them to exhibit a behavior for which they are not responsible, as they have merely followed a force greater than themselves. The impulse within the emotion now subsides, and the emotion itself dissipates. The individual is now calm.

Considering the above model, various human emotions such as joy, sorrow, anger, hatred, love, and shame, once triggered, can produce a set of physiological effects and behavioral responses. In cinema, instead of directly using emotional domain words in actors' dialogues to make the viewer aware of a specific emotion, the filmmaker often chooses to show the physiological or behavioral responses of that emotion. In other words, the filmmaker employs the conceptual metonymy of EFFECT FOR CAUSE to conceptualize the intended emotion. Conversely, the viewer comprehends the intended emotion through this same metonymy. That is, the viewer only sees manifestations of the effect but, through these very manifestations, gains conceptual access to the cause.

For example, in Peyman Maadi's film Snow on the Pines, to demonstrate the absence of love in the life of Ali and Roya and the presence of love in the relationship between Nariman and Roya, the filmmaker shows several effects of this emotion. Through this, the viewer gains conceptual access to the cause—the presence or absence of love. Some of these effects in the film include:

1. Roya and Ali exhibit no passion or excitement while together at the dinner table (Image 1), whereas this excitement is clearly visible when Roya is with Nariman. When Nariman calls Roya before the concert, Roya, upon hearing his voice, is startled, knocks over a glass on her dressing table, and spills its contents. 
2. Roya does not wear makeup for her husband at home. This is understood from her telephone conversation with her mother and also from the scene where she is with Nariman. In that phone call, Roya's mother asks if she needs any cosmetics, but Roya replies that the kohl her mother bought for her a long time ago is not yet finished. Furthermore, the only scene in which Roya is seen applying makeup is when she is preparing to go to the concert with Nariman (Image 2).
3. During a visit, Roya's mother brings Ghormeh Sabzi (Persian herb stew), Ali's favorite food, for him because, according to the mother, Roya refuses to cook it due to its strong smell permeating the house. 

Or, in the film A Separation, directed by Asghar Farhadi, the filmmaker uses the behavioral response of the emotion to conceptualize the character Hojat's anger. The viewer, through this, gains conceptual access to the feeling of rage. For instance, in the hospital scene, when Hojat realizes that Nader pushed his wife, he headbutts Nader in the face (Image 3).

Also, Simin's nose, as she approaches to separate Hojat from Nader, is bloodied by a blow from Hojat. In another behavioral reaction in the same scene, Hojat engages in self-harm, hitting his own head and face with his hands. 

In another scene where Nader and Simin are to pay blood money (Diyeh) to obtain Hojat's consent and drop the lawsuit, Hojat demands that Razieh swear in front of everyone that Nader caused the loss of her pregnancy, and that the child was lost as a result of him pushing her. However, Razieh and Hojat go to kitchen, where Razieh tells him, "I have doubts. I asked a religious authority, and they said if you have doubts, taking the blood money is forbidden (Haram)." Here, Hojat becomes angry again and engages in self-harm, hitting his own head and face (Image 4).

 Or, in the courtroom scene, after Hojat disrupts the order of the session, the judge decides to expel him from the court. Here, Hojat bangs his head against the courtroom door, thereby displaying his anger (Image 5). In effect, the filmmaker uses the metonymy of EFFECT (the behavioral response of anger) FOR CAUSE (the feeling of anger) to conceptualize Hojat's rage. The viewer likewise discerns the presence of anger in this character through this very mechanism.

In summary, it can be argued that one of the key cognitive mechanisms frequently employed by filmmakers for the conceptualization of emotions and by viewers for their comprehension is the EFFECT FOR CAUSE metonymy.

References

Kövecses, Z. (2004) Metaphor and Emotion: Language, Culture, and Body in Human Feeling. New York: Cambridge University Press.

Lakoff, G. & Johnson, M. (1980). Metaphors We Live by. London: The University of Chicago Press.

Radden, G., & Kövecses, Z. (1999). Towards a theory of metonymy. In K. U. Panther & G. Radden (Eds.), Metonymy in Language and Thought, (pp 17–59), Amsterdam: John Benjamins.