Sam is playing a carnival game challenging him to guess which of the 20 cups is hiding the red ball. Unfortunately, he picked the cup directly to the left of the winning cup and thus did not win the stuffed donkey he wanted. According to social psychological research, he is most likely to .

engaging the counterfactual thinking

Explanation:

Counterfactual thinking is about what a person believes or think would happen in the event or situation but the situation or event becomes totally different from the person's expectation. This results in triggering of the negative thoughts that can block one's goal and desire.

These thoughts have a variety of effects on the beliefs, emotions, and behavior of the person. The person may feel regret.

According to the given situation, the Sam has lost the carnival game as he unfortunately picked up the cup which was lying directly left to the winning cup. Thus he may feel negatively and may regret. Thus he get engaged in the counterfactual thinking.