Comparative Study of Self and Co-Twin Representation in Drawings by Twin Children

• Grant number: 25/12586-7
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Humanities - Psychology - Human Development Psychology
• Principal Investigator: Emma Otta
• Grantee: Emma Otta
• Host Institution: Instituto de Psicologia (IP). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• City of the host institution: São Paulo
• Associated research grant: 22/02107-6 - The University of São Paulo twin panel: research on twins' behavior, health, and well-being, AP.TEM

Abstract

The Thematic Project, a collaboration among faculty from Psychology, Dentistry, and Medicine, is dedicated to investigating twin behavior and its relationship with health and well-being from an ontogenetic perspective. Within this context, the current Scientific Initiation work plan specifically focuses on analyzing drawings produced by twin children, with an emphasis on the influence of zygosity. The main hypothesis is that monozygotic (MZ) twins, due to their 100% genetic similarity, will produce drawings of themselves and their co-twins that are more similar than those produced by dizygotic (DZ) twins, who share, on average, 50% of their genes. The analysis will be based on an already collected corpus of drawings from 140 twin children aged 7 to 12. Regarding zygosity, 35.8% are monozygotic and 64.2% are dizygotic. The distribution by sexual composition of the dyads is as follows: 41.9% are female dyads, 29% are male dyads, and 29% are opposite-sex dyads. Each participant completed their drawing individually, seated at an appropriate table, using an A4 sheet of paper and a set of colored pens. The instruction given was: "Draw a portrait of yourself with your brother/sister." Two complementary analyses are planned. One analysis will be based on the first impressions and gestalt evaluations of independent judges for each pair of drawings. This analysis will occur across three dimensions: physical similarity, affective relationship, and power distribution between the figures. The other analysis will be based on a micro-analysis of the drawings, using a system of categories. The points of focus will be: the comparison of bodily characteristics, the detailing of the figures (number of colors, clothing items, and accessories), differences in spatial location, and the affectivity in the relationship between the figures. The expectation is that monozygotic (MZ) twins will produce drawings that are more similar to each other and their co-twins than dizygotic (DZ) twins. (AU)