Introduction. Adolescent sexual development (SD) is a normative task influenced by hormonal changes and individual
factors (Baams et al., 2013; Beyers et al., 2015; Berk, 2017). Recent research suggests that various SD trajectories
during adolescence are possible (Beyers et al., 2016), but there is currently no underlying explanation for these
individual differences in SD during adolescence. Although adolescents go through an abundance of changes as they
mature from prepubertal children to young adults, their temperament and personality are relatively stable (Baams et al.,
2013). Despite this fact, only a handful studies have focused yet on the role of temperament in SD during adolescence.
Integrating Fisher’s Temperament Theory (Fisher et al., 2015), this study aims to elucidate the role of temperament in
SD among Flemish (and American) people during adolescence.

Objective. Three main research objectives describe the aim of the overall research project: (1) An in-depth assessment
of SD during adolescence; (2) A validation of the Fisher Temperament Inventory (Fisher et al., 2015) in a sample of
Flemish adolescents/emerging adults; and (3) The development of an integrated theoretical model describing SD during
adolescence.

Methods. By continuing a longitudinal study, conducting at least two new cross-sectional studies and by performing a
qualitative study, this research will investigate the various objectives. It is the aim to perform one of the cross-sectional
studies at the Kinsey Institute in Indiana, if enough funding is found. The overall research will use constructs that are
relatively new in the field, like the Fisher Temperament Types (Fisher et al., 2015), which is a temperament theory
designed directly on brain science and tested through functional Magnetic Resonance Imaging (fMRI). If enough
funding is found, the fMRI study will also be replicated. Another model that will be used is the Dual Control Model
(DCM) of Sexual Response (Bancroft and Janssen, 2023), which postulates that sexual arousal and associated
processes are dependent on the balance between sexual inhibition and sexual excitation. Other constructs like Sexual
Motives (SM), Sexual Attitudes (SA), Sexual Behaviour (SB) and the Big Five Personality Threats will also play a role in
this research.

Implications. This study aims to contribute to the understanding of SD during adolescence and the underlying factors
that influence it. Potential (clinical) implications may be found in sexual education programs, guiding therapists, and
creating an integrated model of SD during adolescence.