Extending these previous lines of research, the current study examines whether the happiness benefits that we garner from prosocial behaviour, and, in particular, spending money on others, differ depending on whether the target is a strong or weak social tie. Given the previous research demonstrating how important social relationships with close friends and family are for well-being, we hypothesized that participants would be happier after recalling spending money on a strong tie rather than a weak tie. However, given the positive effects that extend through weak ties in one’s social network, it was also possible that participants would be equally happy after recalling spending money on weak ties. Methods Participants Eighty individuals (68% female; Mage = 22.0, SD = 6.4) were approached in public places on the University of British Columbia campus and asked to participate in a study looking at how people spend money and how it affects their state of mind. One individual was removed from this sample because we suspected he did not take the study seriously; his response indicated that he recalled spending money on his ‘‘alter ego’’. All participants provided written consent. This study was approved by the University of British Columbia’s Behavioural Research Ethics Board (H06- 80557). Procedure Participants were randomly assigned to one of two spending recall conditions. They were asked to recall in as much detail as possible the last time they had spent approximately twenty dollars on either someone who they considered to be a strong social tie or someone they considered to be a weak social tie. Specifically, participants in the strong tie condition were asked to: ‘‘Please think back to and describe as vividly and in as much detail as possible the last time you spent approximately twenty dollars ($20) on someone you are very close to (e.g., a good friend, close family member, romantic partner).’’ Participants in the weak tie condition were asked to: ‘‘Please think back to and describe as vividly and in as much detail as possible the last time you spent approximately twenty dollars ($20) on someone you are not very close to (e.g., an acquaintance, a co-worker, a classmate, a friend of a friend).’’ After participants described their spending experience, they reported their current affect levels on the Positive and Negative Affect Schedule [7] (PANAS). This scale asks participants to report their current affect in response to 10 positive affect prompts (e.g., alert, interested, determined) and 10 negative affect prompts (e.g., guilty, scared, hostile), on a scale from ‘‘1 - very slightly or not at all’’ to ‘‘5 - extremely’’. We added the adjective ‘‘happy’’ as an extra item on the PANAS inventory, since happiness was of primary interest to our study, and averaged the eleven positive affect items to form a measure of post-recall positive affect (a = .90). After reporting their affect, participants provided further details about the spending experience, including how long ago the spending experience had occurred (1- in the last two days, 2- in the last week, 3- in the last month, 4- in the last year, 5- a long time ago). Spending Target Matters For Happiness Results We predicted that recalling a purchase made for a strong social tie would lead to higher levels of happiness than recalling a purchase made for a weak social tie. To investigate this question, we compared post-recall positive affect ratings for participants in the strong and weak social tie conditions using an independent samples t-test. There was a significant main effect of spending target, whereby participants randomly assigned to recall a purchase made for a strong tie reported feeling significantly more positive affect (M = 2.76, SD = .88) than participants assigned to recall a purchase made for a weak tie (M = 2.37, SD = .75), t(76) = 2.09, p,.05. Thus, our prediction was supported: participants experienced greater well-being after reflecting upon a purchase made for a strong social tie. We were also interested in how recently participants had spent money on strong or weak social ties. Given that the measure of the delay since spending used unequal time intervals (e.g., days vs. months), we used a non-parametric test. A Mann-Whitney test of the delay since spending indicated that participants spent significantly more recently on strong ties than on weak ties, z = -3.94, p,.001. To ensure that the higher levels of positive affect reported in the strong social tie recall condition were not simply a result of more recent spending behaviour, we conducted an Analysis of Variance with delay since spending entered as a covariate. Supporting the robustness of the effect, participants who recalled a previous purchase made for a strong tie reported feeling more positive affect than participants who recalled a purchase made for a weak tie, even when controlling for the recency of the spending experience, F(1, 75) = 3.91, p = .05. We also investigated whether distinguishing between strong and weak social ties could account for the observed happiness differences better than distinguishing based on relationship type. When three individuals, blind to condition assignment, coded relationships as either family or friend (a = .97), there was substantial overlap between the relationship type classification (i.e., family vs. friends) and the intimacy level classification (i.e., strong vs. weak tie). Family members were more likely to be mentioned in the strong tie condition (vs. the weak tie condition) and friends were more likely to be mentioned in the weak tie condition, suggesting that these two classifications are related, x2(1) = 8.68, p,.005. Importantly, however, when both the family vs. friends and strong vs. weak tie classifications were entered into a regression, only the strong vs. weak tie distinction predicted differences in happiness levels following the spending recall (b = 2.26, p,.05). These results suggest that level of intimacy is a more powerful predictor than the relationship type (b = .08, ns) when it comes to the happiness people reap from prosocial spending. Discussion These data suggest that spending money on people we know well leads to higher levels of happiness than spending money on acquaintances. When participants were randomly assigned to recall a time they had spent money on either a strong or weak social tie, participants who recalled spending on a strong tie reported higher happiness afterward. As such, these findings suggest that to reap the greatest emotional reward from spending on someone else, one should direct their purchases to close others. Consistent with this finding, research on reciprocal altruism and the evolution of cooperation demonstrates that people ultimately benefit from behaving generously and cooperatively toward individuals with whom they are likely to interact in the future PLoS ONE | www.plosone.org 2 February 2011 | Volume 6 | Issue 2 | e17018