# **I INTRODUCTION**

Migration is a divisive issue. Anti-immigrant sentiments are widespread and recent opinion surveys suggest that natives worldwide have become less accepting of migrants.<sup>1</sup> Prejudice against migrants can preclude integration and lead to their social exclusion, inducing large economic and social costs in hosting societies. It is necessary to understand how natives alter their attitudes towards migrants in response to different stimuli in order to design policies and programs more effectively.

We examine how crises affect native altruism and attitudes towards migrants. When facing a common threat, natives may feel solidarity or even kinship with migrants in the same situation, or with society as a whole. We call these positive responses the _empathy channel_ . Alternatively, a crisis could increase competition for scarce resources and trigger native resentment towards migrants, a response we call the _resentment channel_ .

We also study whether individuals between 18 and 25 years old respond differently to migrants during crises. According to a vast literature in social psychology and economics, core attitudes, beliefs, and values are formed mostly during early adulthood and change only slowly after this critical period. The theory of the _impressionable years hypothesis_ posits that people 18 to 25 years old have superior mental plasticity. For instance, several studies have shown that the historical and economic contexts of this time shape basic attitudes, values, and world views (e.g., Greenstein, 1965; Easton et al., 1969; Cutler, 1974; Sears, 1983; Giuliano and Spilimbergo, 2014; Torney-Purta, 2017;). Glenn (1980) and Spear (2000) have proposed scientific explanations for this phenomenon. Glenn (1980) suggests that people are flexible in reacting to social circumstances when they are young but become gradually less so as they age. This decrease in flexibility is due to a drop in energy, loss of brain tissue, disengagement, and less interest in events distant from one’s immediate life, as well as to the accumulation of friends with similar world views. Spear (2000) states that a younger brain in a transitional period differs anatomically and neurochemically from an adult brain. In a young brain, the grey matter in the cortex gradually increases until about the age of adolescence, then sharply declines as the brain sheds neuronal connections superfluous to adult needs.

We examine the effects of the COVID-19 pandemic in Colombia on native altruism and attitudes towards migrants. It is challenging to identify the effect of COVID-19 on attitudes because a simple comparison of individual views beforehand and afterward could confound the effects of the pandemic with unrelated but concurrent events. For instance, in addition to the pandemic and its economic consequences in 2020, many nations implemented policies that same year to restrict immigration, which could arguably also have affected attitudes towards migrants.

To isolate the effects of COVID-19, we conducted an online survey experiment with 3,400 Colombian nationals.

> 1See the evolution of the Migrant Acceptance Index from the Gallup report collected in 140 countries between 2016 and 2019 at: https: //news.gallup.com/poll/320678/world-grows-less-accepting-migrants.aspx

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