What could be the psychological reasons behind a girl pooping herself in fear in such a story?

One reason could be extreme stress. Fear can cause the body to go into a fight - or - flight response, and sometimes the body's normal functions can be disrupted, including bowel control. Another might be a lack of proper coping mechanisms for intense fear.

Maybe she was under extreme stress or fear. Stress can have a physical impact on the body and disrupt normal bodily functions. For example, if she was in a very scary situation like being chased, her body might go into a fight - or - flight response and this could potentially lead to such an accident.

Well, sometimes a girl might poop in her pants because she was too engrossed in an activity. Let's say she was playing a really exciting game outside and didn't want to stop to go to the bathroom. Also, not having access to a toilet in time can be a cause. If she's in a situation where there are no toilets around, like in the middle of a long hike, she might end up having an accident.

One reason could be that she was too engaged in an activity, like the girl on the swings. She was having so much fun that she didn't pay attention to her body's needs. Another reason might be a lack of access to a toilet, like the girl on the long car journey. There was nowhere to go so she had no choice. Also, being distracted by excitement, such as at the school event, can make a girl forget about the urge until it's too late.

Well, it could be a form of creating a sense of the abnormal or the extreme. By coming up with such a story, it grabs people's attention. Also, in some cases, it might be a way to spread rumors or make fun of someone in a very mean - spirited way. However, this is not acceptable behavior. In a more general sense, it might also be an example of how people sometimes create stories around embarrassing or taboo topics just to break the social norms in a story - telling context.

Stress could be a major reason. High stress levels can interfere with a person's ability to relax and fully engage in sexual experiences. Also, past traumas, like sexual abuse, can create psychological barriers that prevent a girl from reaching orgasm.

Maybe she had a sudden stomachache and couldn't hold it any longer. For example, she might have eaten something bad before getting in the car.

Maybe she was playing too hard and ignored the urge to go to the toilet for a long time. Kids often get so engrossed in their play that they forget about their bodily needs until it's too late. Also, it could be that there was some kind of problem with the toilets around her. For instance, if all the nearby public toilets were locked or out of order and she couldn't hold it any longer.

No, such stories are not very common in mainstream literature. Most literature focuses on more positive or complex emotions and situations rather than this rather extreme and embarrassing one.

One possible reason could be a need for attention. Sometimes children act out in unusual ways to get their parents to focus on them. If the girl feels neglected, she might think that this extreme behavior will make her mom pay more attention.