Table 1.

The operational categories used to analyze the explanations provided by participants in Study 1.

Curiosity	The TPM: Being curious means that you get pleasure from learning something that you did not previously know. Definition in Problem Solving: Curiosity is experienced by problem solvers when, in the initial stage (problem setting), they feel a state of tension related to not knowing the solution. It is the experience of “missing something” (the solution) that prompts them to look for what they do not know yet (i.e., to move from the unknown to the known). When they know the solution, they know something new and this leads to a final state of relief. Examples (most enjoyable problems): “I was very intrigued by the problem… and then also by the solution” [pigs in a pen]; “This was the problem that from the beginning most roused my curiosity” [triangle]. Examples (least enjoyable problems): “I did not find the solution and I felt as if I was left up in the air, out of the picture” [pigs in a pen]; “The problem did not make me curious, even after I learned what the solution was” [five-square].
Virtuosity	The TPM: Virtuosity refers to the pleasure you have when you feel you are doing something well. Definition in Problem Solving: Virtuosity relates to experiencing the mastery of being able to cope with the task, to reason about possible solution paths. When problem solvers find the correct solution, they feel proud of their reasoning skills. (note: both virtuosity and curiosity concern stepping from an initial state of not knowing the solution—and not knowing whether one will be able to discover it – to knowing it. However, the focus in curiosity is on “learning a new content,” whereas in virtuosity the focus is on discovering, or confirming, one's reasoning skills). Examples (most enjoyable problems): “The kind of reasoning involved was both intuitive and mathematical and presupposed a bit of knowledge of the subject” [circumference]; “It was thought provoking in terms of the reasoning which it necessitated” [eight-coins]. Examples (least enjoyable problems): “I remained focused for too long on the lines forming the head [in the deer problem] and my brain got stuck; then it was impossible to start reasoning in other directions”; “In order to solve this problem [the circumference problem] you needed to apply geometrical rules that you were supposed to remember.”
Violation of expectations	The TPM: You search for an interpretation of the source of the violation of your expectation. You get pleasure from the violation of expectations followed by a return to a stable state. Definition in Problem Solving: A violation of expectations is experienced by problem solvers when they realize that a change in their initial mental representation of a problem is needed (since it is misleading) and that information that has been viewed as insignificant is in reality relevant to the solution (i.e., a shift in the focus of attention). Examples (most enjoyable problems): “The solution leads us away from the usual way of thinking because we are used to thinking of a square as being oriented with two vertical and two horizontal lines while the solution requires them to be oblique” [pigs in a pen]; “I focused from the beginning on moving the lines representing the head and only those. I never thought of moving the legs!” [deer]. Examples (least enjoyable problems): “The position that the deer has in the solution (sitting that way!) is not a normal position” [deer]; “I thought we had to move the coins only on the plane, while the solution was to put some on top of others” [eight coins].
Feeling of surprise	The TPM: This emotion is familiar to scientists but is widespread in entertainment as well. It is a feature much sought after in the mystery genre. Definition in Problem Solving: The experience of surprise (positive surprise, negative surprise or no surprise) is associated with the disclosure of the solution. (note: Feeling of surprise is associated with unexpectedness, and is therefore often likely a consequence of the problem solvers' expectations being violated—see previous category. When, in order to explain their choices, participants explicitly referred to their expectations as being violated, responses were classified in the previous category. When they simply referred to the amazement (positive) or perplexity or no feeling of surprise (both negative) that they experienced when the solution was revealed, responses were classified in the present category). Examples (enjoyable problems): “The solution surprised me” [deer]; “The solution astonished me” [pigs in a pen]. Examples (least enjoyable problems): “The solution did not surprise me” [five square]; “The correct solution surprised me negatively: I found it meaningless”[eight coins].
Joy of verification	The TPM: This emotion is familiar to scientists but is widespread in entertainment as well. The joy of verification is a characteristic of many puzzles. Definition in Problem Solving: Joy of verification is experienced by problem solvers in terms of proximity to the correct solution. (note: this category differs from Virtuosity in that participants do not explicitly refer to the pleasure of the reasoning acts they were engaged in but to their experience of verifying that their solution was in fact the correct one—or close to it). Examples (most enjoyable problems): When I received the response sheet, I verified that my solution was the right one” [circumference]; “I came very very close to the correct solution” [deer]. Examples (least enjoyable problems): “I was close but still wrong” [deer]; “When I was given the solution, I realized I was very far away from the correct solution” [triangle].
Diminishment	The TPM: If the reinterpretation paints a less desirable picture of the protagonist or the event (…), then you will find the event to be humorous. Definition in Problem Solving: Diminishment in problem solving is associated with a person realizing that the solution was simple while they had been trying much more complex reasoning paths. This can lead to enjoyment when the person makes fun of his/her own too convoluted reasoning (i.e., diminishes him/herself) or can lead to negative feelings when the person diminishes the problem to the status of a trivial one. Examples (most enjoyable problems): “When I read the solution, I found it so interestingly simple” [pigs in a pen]; “The solution was so simple and obvious, but at the same time very clever” [deer]. Examples (least enjoyable problems): “It was a very easy problem in the end” [circumference problem]; “The problem was too banal and the solution too elementary” [triangle].
Happiness	Definition in Problem Solving: A pure expression of amusement and/or enjoyment without any specific explanation for its cause. Examples (most enjoyable problems): “I liked it from the very beginning” [triangle]; “I found the solution nice” [deer]. Examples (least enjoyable problems): “Even after I learned the solution, I did not like it” [five-square]; “I do not like this problem” [eight coins].
Content type	Definition in Problem Solving: An expression of amusement and pleasure related to the specific kind of process that needs to be activated in order to search for a solution, independently of feeling able to do it or not. Examples (most enjoyable problems): “I always enjoy working on problems with non-geometrical figures” [pigs in a pen] ; “I adore puzzles that require me to pay great attention to the words used in the text” [eight coins]. Examples (least enjoyable problems): “I don't like Geometry” [circumference]; “I have never liked solving Geometry problems” [circumference].
Superficial aspects	Definition in Problem Solving: An expression of amusement and pleasure related to the superficial elements of the problem or to the images depicted in the problem. Examples (most enjoyable problems): “The problem had a simple structure and did not depend too much on the images” [triangle]; “The image was nice” [pigs in a pen]. Examples (least enjoyable problems): “It was too stylized ” [deer problem]; “The elements in the image depended too much on the overall configuration” [five square].