Phd in PSYCHOLOGY AND SOCIAL NEUROSCIENCE

Thesis title: Doing Good for the Environment and Living Well: A Daily Diary Approach to the Study of Youths’ Pro-environmental Behavior and Eudaimonic Well-being

This dissertation aimed to explore the dynamic relationships between Pro-Environmental Behaviors (PEB; Steg & Vlek, 2009), actions aimed at benefiting the environment, Prosocial Behaviors (PB; Eisenberg, 2006), acts of care toward others, and Eudaimonic Well-Being (EWB), namely experiences of meaning in life and closeness to others (Ryff & Singer, 2008), in the everyday lives of adolescents and young adults. Specifically, it sought to understand the reciprocal influences between PEB and PB, the impact of daily PEB on EWB, and how self-transcendence values (Schwartz, 1992) might moderate these associations. Using a within-person approach, daily diary data (Bolger et al., 2003) were collected and analyzed through Dynamic Structural Equation Modeling (DSEM; Hamaker et al., 2018), to investigate the day-to-day reciprocal relations among these variables. Moreover, adopting an experimental approach called Within-Person Encouragement Design (WPED; Schmiedek & Neubauer, 2020), this thesis took a causal perspective to examine the putative causal effect of daily PEB on daily EWB. Study I explored the reciprocal influence between PEB and PB in a sample of young adults assessed once a day for 21 days. It found a significant positive spillover effect from PB to PEB (β = .307, 95% CI [.103, .504]), suggesting that engaging in prosocial behaviors led to increased pro-environmental actions on subsequent days. However, no reverse effect from PEB to PB was observed, and self-transcendence values did not moderate this relationship. The results indicated that PB can act as a motivator for PEB in young adults, showing that caring for others can foster greater care for the environment. Study II focused on adolescents and investigated the impact of daily PEB on EWB over a 28-day period. The results showed a significant positive spillover effect from PEB to EWB (β = .157; 95% CI: [.063, .244]), meaning that when adolescents engaged in more PEBs than usual, they experienced higher levels of EWB on subsequent days. Moreover, similar to Study I, self-transcendence values did not moderate this relationship. This study highlighted the immediate benefits of PEB for adolescents' well-being, suggesting that daily PEBs could promote meaning in life and closeness to others. Study III aimed to investigate the daily impact of PEBs on EWB from a causal perspective, examining whether manipulating daily PEBs would result in higher levels of EWB on those days. Using a WPED design in a sample of young adults followed over 21 days, participants were encouraged on random days to enact more PEBs than they usually did. The findings indicated that on days when participants received the encouragements, they reported higher-than-usual PEBs (β = .093, 95% CI: [.038, .149]), and, importantly, higher levels of EWB (β = .227, 95% CI: [.048, .422]). These findings contribute to confirm, from a causal perspective, the positive influence of pro-environmental behaviors on the eudaimonic well-being of young people. Overall, this dissertation demonstrated the role of acting prosocially on a daily basis in motivating environmental protection. Moreover, it highlighted that pro-environmental acts can promote eudaimonic experiences in young people, thus they may contribute to protect their mental health against the detrimental effects of environmental issues (Pereira & Freire, 2021).