Measures

A persuasion task and a set of ToM tasks were administered.

A persuasion production task was designed drawing on the persuasion understanding task from the “Strange Stories” battery (Happé, 1994). Happé's task consists of a story in which a boy lies to his school canteen's cook by telling him that he would not have any dinner at home that night, so he asks the cook to double his portion of sausages, which is his favorite food. The participant is asked whether what the character says is true or not, as well as to explain why he says that; therefore, the task measures the ability of the participants to attribute the character a motivation of igniting a sense of pity in the cook by creating a false belief idea to achieve a personal benefit.

The task that has been designed consists of a brief story in which the participant is the main character and is assigned a situation in which they must produce persuasive arguments that relate to a given motivation, which is also assigned to him/her as follows: “You are going to your friend's birthday celebration, and you realize that they brought your favorite cake for this party. Everyone is to receive one slice only. When your friend's mother finishes cutting the cake, you see that there is a slice left. You have already eaten one. What would you say to your friend's mother to convince her to give it to you?” Once the participant had provided their first answer, the experimenter, role-playing a mother, asked them for a new argument, and this was repeated up to three times, following Slaughter et al. (2013) and Peterson et al. (2018) procedure. This task assesses the ability to develop persuasive arguments aimed at achieving one's own benefit.

Coding and scoring. Two indicators of persuasion ability have been considered: the variety and the quality of the arguments.

Variety. 1 point is awarded for each different persuasive argument (0 to 3 points).

Quality. Each of the three arguments provided by each participant is classified according to the following coding system, meaning that the total quality score for a persuasive argument ranges from 0 to 4 points.

Expressions that are not persuasive: 0 points (“I would not tell her anything,” “I do not care if she does not give it to me”).

Simple requests or expressions of politeness: 0.5 points (“give it to me,” “please, can you give it to me?”).

Persuasive arguments: Any expressions targeted to the persuadee that include a reason to convince them. Each argument is rated considering two quality indicators simultaneously: self-oriented vs. hetero-oriented and material vs. mental focused.

Self-oriented vs. hetero-oriented. 1 point: an argument focused on a personal need or desire (“it is the cake that I like the most,” “I am very hungry,” “my mother is not going to serve dinner for me”); 2 points: an argument that focuses on the individual being persuaded or on a third party (“because I am your son's best friend,” “if no one is going to eat it, you will have to throw it away,” “you have made the richest cake I have ever tasted”).

Material vs. mental. 1 point: an argument that focuses on material gain (“my mother is not going to serve dinner for me,” “if no one is planning to eat it, you will have to throw it away”); 2 points: an argument focusing on a consequence or mental benefit (“it is the cake that I like the most,” “you are an excellent cook”).

To calculate persuasion ability scores, it has been used for each participant the statement with the highest score in terms of quality.

Total persuasion ability score. Sum of the variety score and the total quality score (0 to 7 points).

A cognitive ToM score and an affective ToM score were obtained. Cognitive ToM score was obtained from the False Belief about Location of Second-Order task (Núñez, 1993) and cognitive questions of Faux Pas tasks (Baron-Cohen et al., 1999; Zalla et al., 2009). Affective ToM score was obtained from the Belief-Emotion (negative valence) task (Harris et al., 1989), and Hidden Emotion task (Harris et al., 1986).

Second-Order False Belief about Location (Núñez, 1993). It assesses the ability to attribute someone a false belief about a third person's knowledge of an object's location. Sally puts her marble in her basket and leaves the room; meanwhile, Anna moves Sally's marble into her box without realizing that Sally is watching. The participant is asked where Anna thinks that Sally would look for her marble, as well as to justify their response.

Coding and scoring. 0 points: no second-order reasoning (“in the box, because her marble is there”); 1 point: second-order reasoning by implicitly referring to the two mental states (“in the basket, because she has not seen that Sally was watching”); 2 points: an explicit reference to one of the two mental states (“in the basket, because Anna does not know that Sally was watching”); 3 points: an explicit reference to the two mental states (“in the basket, because Anna thinks that Sally does not know what has happened”).

Faux Pas (Baron-Cohen et al., 1999; Zalla et al., 2009). It tests the ability to understand that a character who does not know certain information can say something that unintentionally produces a negative emotion in another person. Two Faux Pas stories were administered. In each task, the following questions have been posed: (1) the detection question. “In the story did anyone say something they should not have said or something awkward?”; (2) the person identification question: “Who said something they should not have said or something awkward?”; (3) the content question: “What did they say that they should not have said or what was it awkward?”; (4) the explanation question: “Why should not they have said it or why was it awkward?”; (5) the false belief question [This question was different for each story]: “Did they know/remember that…?”

In this study the answers to Explanation Question and False Belief Question have been taken into account jointly to check whether the child understands that the faux pas was a consequence of the speaker's false belief rather than being an action with malicious intent.

Coding and scoring. 0 points: no attribution of a false belief to the speaker (“because you must not speak ill of someone”); 1 point: implicit attribution of ignorance to the speaker that makes the blunder by referring to the effect produced in the person that receives the harm (“because the girl that is in the toilet would feel bad”); 2 points: allusion to the perspective of the person that makes the blunder (“because they do not know if the girl is in the toilet and can listen to what they are saying”).

Negative Belief-Emotion (Harris et al., 1989). It assesses the ability to attribute to another person a negative emotion caused by a wrong belief. The participant is shown a box of medicines that actually contains sweets, and is asked how the character will feel when he/she receives the box without opening it, and why.

Coding and scoring. 0 points: no attribution of a negative emotion (“he/she will be happy, because he/she loves sweets”); 1 point: attribution a negative emotion by referring to the supposed content (“sad, because no one likes medicines”); 2 points: an explicit reasoning about the mental state (“disillusioned, because he/she does not know that actually there are sweets inside”); 3 points: an explicit mentalistic reasoning (“sad, because he/she will believe there are medicines”).

Hidden Emotion (Harris et al., 1986). This task assesses the skill to understand that a person can feel one emotion but feign another. The participant is told the story about a character that feels sad after being mocked by their classmates, and who tries to hide his feelings so they stop mocking him. The student is asked how the character tries to look (choosing a neutral, a sad, or a happy face), and why.

Coding and scoring. 0 points: choosing the sad face; 1 point: choosing the neutral or happy face and alluding to the behavioral consequence the character tries to avoid (“so that they do not call him baby”); 2 points: an implicit reference to hide the emotion (“so that they do not see he is sad”); 3 points: providing an explicit mentalistic justification (“so that they do not know he is sad”).

Cognitive ToM score ranges from 0 to 7 points. Affective ToM score ranges from 0 to 6 points. And it was also calculated a total ToM score ranging from 0 to 13 points.