Collaboration promotes proportional reasoning about resource distribution in young children.

Is it human nature to share altruistically and to expect others to do so? Or do we begin life expecting resources to flow exclusively from individual efforts and merit? Although humans differ substantially in their attitudes about sharing and resource distribution, the idea that we should share with others according to our means permeates discourse in the western world, from political policy making to religious scripture. Does this sensitivity to sharing and proportional giving come naturally to humans, or does the expectation that people give according to their means result primarily from culturally-mediated learning experiences? By some accounts, children initially seek to maximize personal gain and selfishly allocate resources to themselves, even when others have contributed to earning the resources in question (Hook, 1978; Lane & Coon, 1972). According to these studies, children’s intuitions about fair resource distribution change gradually as they internalize cultural norms and as they become sensitive to proportionality and the numerical differences between amounts. Children first learn to distribute resources evenly, then to give more to those who work hardest, and finally, as their numerical sense evolves, to divide resources proportionally, according to the efforts of individuals (Damon, 1975; Damon, 1977; Hook, 1978; Hook & Cook, 1979; Inhelder & Piaget, 1964). In early studies, a barrier to testing the development of equity and fairness intuitions was the finding that children have difficulty reasoning about proportions before the age of 7 (Noelting, 1980; Piaget & Inhelder, 1958; Piaget & Inhelder, 1975; Siegler & Vago, 1978). However, recent studies using simpler methods and stimuli that are more interesting to children have challenged this conclusion (Goswami, 1995; Mix, Levine & Huttenlocher, 1999; Singer-Freeman & Goswami, 2001). For example, Singer-Freeman and Goswami (2001) found that children as young as 3 years of age can match the proportions of pizza and candies that have been eaten. Further, research in pre-linguistic infants finds that 6-month-olds are sensitive to proportion in simple numerical discrimination tasks (McCrink & Wynn, 2007). However, there are also well-documented ways in which young children, and sometimes adults, experience difficulty reasoning about proportion (e.g., overlooking the importance of the denominator when reasoning about fractions; Reyna & Brainerd, 1994; 2008). In one recent study, McCrink, Bloom, and Santos (2009) found some sensitivity to proportion in 5-year-olds’ intuitions about resource distribution. Children played a “Giving Game” in which they received tokens from two animal puppets and were asked to judge which puppet was nicer. Across trials, the total number of tokens that each animal possessed was manipulated, as was the number that each animal gave to the child. In one key set of contrasts, the experimenters pitted the absolute amount against the proportion (i.e., one puppet shared 3 of his 4 chips, and the other puppet shared 6 of his 12 chips). In this way, the experimenters tested children’s sensitivity to proportion when assessing generosity. Whereas adults based their niceness judgments on the proportion given on these trials, 4- and 5-year-olds systematically judged that the puppet who gave a larger absolute amount was nicer. When the two puppets gave identical amounts, 5-year-olds, but not 4-year-olds, now exhibited some sensitivity to proportion. Overall, however, children were far less sensitive to proportion than were adults, and instead favored individuals who gave a greater absolute amount. The results of McCrink et al. (2009) raise the question of why children and adults differ in their evaluations of niceness. One possibility is that young children are unable to reason about proportion in this type of experimental setting – e.g., because of the need to simultaneously represent two quantities and compare them. Although this is possible, it is unlikely since the study was similar to other recent experiments that have found greater sensitivity to proportion, like those mentioned above. Another possibility is that children and adults have distinct meanings for the word nice, and it is for this reason that only adults consider fairness when interpreting it. However, previous studies suggest that in some contexts, children and adults treat nice similarly (e.g., Heyman & Gelman, 1998, 1999). For example, Heyman and Gelman (1999) showed that, like adults, children as young as age 4 think that the words nice and mean relate to mental life, rather than simply reflecting types of behaviors. Finally, a third possible explanation for McCrink et al.’s finding of age-related differences, which we explore in the present research, is that children initially reserve the use of proportion information to situations that invoke intuitions of merit, where resources are distributed according to each individual’s contribution to acquiring them (e.g., where 50% of effort merits 50% of the resources, rather than 20%). On this proposal, early proportional reasoning may depend on children having specific expectations about how all resources should be distributed. When two individuals give generously – i.e., without an obligation to give – children may not attend to leftover resources because they do not have expectations that they should be shared. Adults, in contrast, may recognize that differentiating the “niceness” of two generous acts can only be done relative to the giving power of each individual, and thus may actively consider leftover resources when making their judgments. Adults, but not children, may expect individuals to share according to their means. We assessed this possibility by comparing reasoning in a non-collaborative context like that used by McCrink et al. (2009) to a collaborative context in which recipients contributed to the acquisition of the resources they were given. Previous studies find that, for adults, collaborative contexts make the notion of equitable resource distribution highly salient (Cappelen, Hole, Sorensen, & Tungodden, 2007; Cherry, Frykblom, & Shogren, 2002; Frohlich, Oppenheimer, & Kurki, 2004; Oxoby & Spraggon, 2008; Ruffle, 1998). Also, there is recent evidence that preschoolers distribute resources evenly when they are earned collaboratively (Warneken, Lohse, Melis, & Tomasello, 2011). Based on these findings, we asked whether children would be more sensitive to proportion in a “Giving Game” when resources were earned collaboratively by a giver and a recipient, rather than by the giver in isolation.