Om chance, t(15) = 4.140, p = 0.001, t(15) = 2.449, p < 0.05, and t(15) = 4.000, p = 0.001, for the uneven, even-poor, and even-rich trials, respectively. To further substantiate these findings, we directly compared children's performance across the trial types. A 2 (Age Group: 3, 5) ?3 (Trial Types: uneven, even-poor, even-rich) mixed-model repeated measures ANOVA yielded a main effect of Age Group, F(1,31) = 18.128, p < 0.001, 2 = 0.37, showing the 5-year-old children afforded more items to the poor recipient (M = 0.71, SE = 0.04) than the 3-year-old children (M = 0.50, SE = 0.04). Additionally, the analysis revealed a main effect of Trial Type, F(2,62) = 3.482, p < 0.05, 2 = 0.10. There was no effect of the interaction term, F < 1. Post hoc comparisons for the Trial Types showed that even-poor and even-rich trials differed from each other, t(32) = 2.613, p < 0.05 (all other p's > 0.10). As we were interested whether there were general changes in children’s performance over time (e.g., indicating that even theData were coded by the experimenter. For each trial, participants received a score of 1 if they chose the option that afforded relatively more items to the poor recipient. That is, they received a score of 1 when they chose the (3/1) option in the TSU-68 site uneven trials, the (3/1) option in the even-poor trials and the PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19905010 (2/2) option in the even-rich trials. Scores were recorded as proportional measures of equitable choices for each trial type. 12 children (35 ) were recoded by a second person. Both 
raters agreed to 98 . Experiment 2 examined whether children distributed more items to poor than to wealthy recipients. That is, in contrast to Experiment 1 (where the crucial manipulation was realized between trials) we were interested whether within a trial typeFIGURE 2 | Panel (A) shows the mean proportion of trials on which participants chose the option that afforded relatively more items to the poor recipient than to the rich recipient in Experiment 2. Panel (B) shows the mean proportion of trials (averaged across trial types) per block in Experiment 2. Error bars indicate standard errors of the means.www.frontiersin.orgJune 2014 | Volume 5 | Article 344 |PaulusOrigins of human charity3-year-old children showed some preference for the poor at the beginning of the experiment), we additionally compared performance across purchase A-83-01 Blocks (see Figure 2B). Given that the previous analysis did not reveal an interaction effect of age group and trial type (i.e., trial type was orthogonal with respect to the age), we averaged for every child the data for each block over all trials. Thus, we calculated for every participant an average performance value for each block. A 2 (Age Group: 3, 5) ?4 (Blocks: 1, 2, 3, 4) mixed-model repeated measures ANOVA yielded a main effect of age group, F(1,31) = 18.498, p < 0.001, 2 = 0.37, replicating the finding that the 5-year-old children awarded more items to the poor than the 3-year-old children. Additionally, the analysis showed an interaction effect between the factors Age Group and Block, F(3,93) = 2.979, p < 0.05, 2 = 0.09. Post hoc independent samples t-tests were performed to compare age differences for every block. These analyses showed that the performances of the two age groups differed significantly from each other in the first block, t(31) = 4.462, p < 0.001, the third block, t(31) = 2.576, p < 0.05, and the fourth block, t(31) = 2.211, p < 0.05, but not the second block, t(31) = 0.783, p = 0.44.DISCUSSIONonly.Om chance, t(15) = 4.140, p = 0.001, t(15) = 2.449, p < 0.05, and t(15) = 4.000, p = 0.001, for the uneven, even-poor, and even-rich trials, respectively. To further substantiate these findings, we directly compared children's performance across the trial types. A 2 (Age Group: 3, 5) ?3 (Trial Types: uneven, even-poor, even-rich) mixed-model repeated measures ANOVA yielded a main effect of Age Group, F(1,31) = 18.128, p < 0.001, 2 = 0.37, showing the 5-year-old children afforded more items to the poor recipient (M = 0.71, SE = 0.04) than the 3-year-old children (M = 0.50, SE = 0.04). Additionally, the analysis revealed a main effect of Trial Type, F(2,62) = 3.482, p < 0.05, 2 = 0.10. There was no effect of the interaction term, F < 1. Post hoc comparisons for the Trial Types showed that even-poor and even-rich trials differed from each other, t(32) = 2.613, p < 0.05 (all other p's > 0.10). As we were interested whether there were general changes in children’s performance over time (e.g., indicating that even theData were coded by the experimenter. For each trial, participants received a score of 1 if they chose the option that afforded relatively more items to the poor recipient. That is, they received a score of 1 when they chose the (3/1) option in the uneven trials, the (3/1) option in the even-poor trials and the PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19905010 (2/2) option in the even-rich trials. Scores were recorded as proportional measures of equitable choices for each trial type. 12 children (35 ) were recoded by a second person. Both raters agreed to 98 . Experiment 2 examined whether children distributed more items to poor than to wealthy recipients. That is, in contrast to Experiment 1 (where the crucial manipulation was realized between trials) we were interested whether within a trial typeFIGURE 2 | Panel (A) shows the mean proportion of 
trials on which participants chose the option that afforded relatively more items to the poor recipient than to the rich recipient in Experiment 2. Panel (B) shows the mean proportion of trials (averaged across trial types) per block in Experiment 2. Error bars indicate standard errors of the means.www.frontiersin.orgJune 2014 | Volume 5 | Article 344 |PaulusOrigins of human charity3-year-old children showed some preference for the poor at the beginning of the experiment), we additionally compared performance across blocks (see Figure 2B). Given that the previous analysis did not reveal an interaction effect of age group and trial type (i.e., trial type was orthogonal with respect to the age), we averaged for every child the data for each block over all trials. Thus, we calculated for every participant an average performance value for each block. A 2 (Age Group: 3, 5) ?4 (Blocks: 1, 2, 3, 4) mixed-model repeated measures ANOVA yielded a main effect of age group, F(1,31) = 18.498, p < 0.001, 2 = 0.37, replicating the finding that the 5-year-old children awarded more items to the poor than the 3-year-old children. Additionally, the analysis showed an interaction effect between the factors Age Group and Block, F(3,93) = 2.979, p < 0.05, 2 = 0.09. Post hoc independent samples t-tests were performed to compare age differences for every block. These analyses showed that the performances of the two age groups differed significantly from each other in the first block, t(31) = 4.462, p < 0.001, the third block, t(31) = 2.576, p < 0.05, and the fourth block, t(31) = 2.211, p < 0.05, but not the second block, t(31) = 0.783, p = 0.44.DISCUSSIONonly.
