Métodos
The study was conducted according to American Psychological Association ethical standards and international and national children’s rights laws. After the school authorities’ approval, information meetings were carried out in schools, in which families had the opportunity to interact with the members of the research group. Only children who were authorized through written informed consent participated in the study. One hundred and four participants were recruited, but 17 were eliminated because they did not have information on parental reports, and 2 because they did not pass the Matrix pretest. The final sample consisted of 85 Argentinean children (47 girls, 38 boys), 40 4-years-old, and 45. we used the Socioeconomic Level Scale (NES) (Colombo & Lipina, 2005) that measured: a) the number of UBN indicators at home; b) health history of the child; c) home stimulation; and d) demographic variables (e.g., age, gender, time of residence in the place). Following the national poverty criteria (Instituto Nacional de Estadísticas y Censos, 2010) we considered as low SES any home with the presence of at least one of the following poverty indicators: (1) Subsistence capacity: head of household with incomplete primary school educational level, and more than four dependents. (2) School truancy: presence of school-aged children (6–15 years old) who do not attend any educational system. (3) Inappropriate dwelling: the house is a hotel or pension, poor housing or other housing not built for residential purposes. (4) Sanitary deficiencies: home with no flush toilet. (5) Overcrowding: home in which the ratio of the total number of home members to the number of rooms used to sleep is equal or higher than 3. Non-verbal ability measure The Matrix subtest of KABC-II (Kaufman & Kaufman, 2004), also known as Pattern reasoning subtest, was used to assess non-verbal ability. In this gold standard test for non-verbal ability, children are presented with an incomplete matrix containing shapes, and a group of shapes that could complete the matrix. The experimenter says “What of these shapes (pointing to the group of shapes) goes here (pointing to the incomplete place)?”. Children should identify relationships between the shapes and point to the only shape that completes the matrix. The test consists of 48 trials, with both figurative and abstract visual stimuli, grouped into blocks of 5 items. The test was interrupted when a child answered incorrectly to all items in a block. We administered the Child Behavior Questionnaire-Very Short Form, Spanish version (Putnam & Rothbart, 2007), to analyze child temperament through parental report. Specifically, this questionnaire measures the three theoretically relevant dimensions or factors previously mentioned: Negative Affect (anger/frustration, discomfort, fear, sadness, and low soothability), Extraversion or Surgency (activity level, impulsivity, high-intensity pleasure, low shyness, approach/positive anticipation, and smiling/laughter), and Effortful Control (attentional focusing, inhibitory control, low-intensity pleasure, and perceptual sensitivity) (Putnam & Rothbart, 2007). The CBQ-VSF consists of 36 statements addressing the three dimensions of temperament (each dimension is addressed by 12 statements about child behavior). Table 1 shows the items of this version in English and Spanish. Parents or caregivers must establish the degree of agreement or disagreement with them on a Likert-type scale of seven values. Each statement can take a score from 0 to 7 and the score of each dimension is found by averaging the scores of the statements that compose it, so it also takes values from 0 to 7 . The dependent variable is the average score for each dimension. Teacher’s Temperament report We also used the Spanish version of the CBQ-VSF (Putnam & Rothbart, 2007) for teachers’ reports, but before administering the questionnaire, 9 items were excluded because they refer to home situations, as it was done in previous studies (Blair & Razza, 2007). Thus, the teachers’ answers were considered as “Not Applicable” in two surgency items (i.e., S16 “Likes to go high and fast when pushed on a swing”, S25 “Is full of energy, even in the evening”); three negative-affect items (i.e., N8 “Tends to become sad if the family's plans don't work out”, N26I “Is not afraid of the dark”, N35 “Becomes upset when loved relatives or friends are getting ready to leave following a visit”) and four effortful control items (i.e., E6 “Prepares for trips and outings by planning things s/he will need”, E12 “Notices it when parents are wearing new clothing”, E24 “Is quickly aware of some new item in the living room”, E36“Comments when a parent has changed his/her appearance”).