Beyond “The more the better”: The impact of altruism degree on moral evaluation and its moderating mechanism

doi:10.3724/SP.J.1041.2026.0935

Abstract

Abstract:

Altruistic behavior is a positive act that benefits others, but is greater altruism necessarily perceived as more moral? From a third-party perspective on altruism, the present research systematically examined the relationship between the degree of altruism and moral evaluation across seven studies (N = 1,798), and further elucidated the underlying mechanism and boundary conditions. The findings revealed that observers’ moral evaluation of highly altruistic behavior was lower than that of moderately altruistic behavior, with perceived teaching function mediating this effect (Studies 1a and 1b). Using a “manipulated mediator as moderator” design, we provided causal evidence for the mediating role of perceived teaching function (Studies 2a and 2b). Self-uncertainty moderated the association between the degree of altruism and perceived teaching function: higher self-uncertainty reduced observers’ perceptions of the teaching function of highly altruistic behavior, thereby decreasing moral evaluation (Studies 3 and 4). A cross-experiment internal meta-analysis further supported the robustness of these results (Study 5). Overall, the present research reveals a nuanced relationship between altruistic behavior and moral evaluation in the contemporary context: altruism is not simply a case of “the more, the better”, and excessive altruism may prove counterproductive. These findings advance understanding of the social evaluation of altruistic behavior and offer a novel theoretical perspective for promoting social harmony and moral development.

Key words: Altruistic Behavior, Moral Evaluation, Teaching Function, Self-uncertainty

SUN Sijie, ZHAO Huanhuan, PI Qiao, ZHANG Heyun. (2026). Beyond “The more the better”: The impact of altruism degree on moral evaluation and its moderating mechanism. Acta Psychologica Sinica, 58(5), 935-960.

Figures/Tables 19

Figure 1. The hypothesized moderated mediation model.

Table 1 Correlations among variables

variable	1	2	3	4	5
1. Gender	—	?0.001	?0.17	?0.26^**	?0.21^*
2. Age	0.12	—	0.31^***	0.29^***	0.23^*
3. Teaching function	?0.11	0.07	—	0.79^***	0.73^***
4. Morality of the behavior	0.20	0.06	0.50^***	—	0.63^***
5. Moral character	?0.01	0.11	0.56^***	0.70^***	—

Figure 2. Differences in dependent-variable ratings by degree of altruism.
Note: Error bars represent standard errors. ^**p < 0.01, ^***p < 0.001.

Table 2 Correlations among variables

variable	1	2	3	4	5
1. Gender	—	0.04	?0.04	?0.13	?0.10
2. Age	?0.09	—	0.16	0.09	0.003
3. Teaching function	0.07	0.23^**	—	0.74^***	0.62^***
4. Morality of the behavior	0.03	0.12	0.79^***	—	0.86^***
5. Moral character	0.06	0.12	0.81^***	0.87^***	—

Figure 3. Differences in dependent-variable ratings by degree of altruism.
Note: Error bars represent standard errors. ^**p < 0.01, ^***p < 0.001.

Table 3 Manipulation check results for perceived teaching function

variable	Low teaching function	Control	High teaching function	F	η2 p
Moderate altruism	3.30 ± 1.20	5.65 ± 0.95	5.94 ± 0.69	73.57^***	0.32
High altruism	3.40 ± 1.49	4.28 ± 1.70	5.52 ± 1.06	38.58^***	0.20
Total	3.35 ± 1.35	4.96 ± 1.53	5.74 ± 0.91	102.70^***	0.40

Figure 4. Differences in moral evaluation of the behavior and perceived moral character by degree of altruism and teaching-function manipulation.
Note: Error bars represent standard errors. ^***p < 0.001. ns = not significant.

Figure 5. Moderating effects of teaching function on the relationship between degree of altruism and moral evaluation.

Table 4 Manipulation check results for perceived teaching function

variable	Low teaching function	Control	High teaching function	F	η2 p
Moderate altruism	3.32 ± 1.32	5.36 ± 1.16	5.83 ± 0.83	73.46^***	0.28
High altruism	3.47 ± 1.34	4.87 ± 1.52	5.42 ± 1.16	40.80^***	0.18
Total	3.39 ± 1.33	5.13 ± 1.37	5.62 ± 1.02	109.93^***	0.37

Figure 6. Differences in moral evaluation of the behavior and perceived moral character by degree of altruism and teaching-function manipulation.
Note: Error bars represent standard errors. ^***p < 0.001. ns = not significant.

Figure 7. Moderating effects of teaching function on the relationship between degree of altruism and moral evaluation.

Table 5 Correlations among variables

variable	1	2	3	4	5	6
1. Gender	—	?0.02	?0.19^***	?0.18^**	?0.12^*	0.14^*
2. Age	?0.03	—	0.27^**	0.12^*	0.20^***	?0.42^***
3. Teaching function	?0.24^**	0.21^**	—	0.69^***	0.64^***	?0.41^***
4. Morality of the behavior	?0.17^*	0.03	0.69^***	—	0.79^***	?0.28^***
5. Moral character	?0.11	0.07	0.56^***	0.73^***	—	?0.31^***
6. Self-uncertainty	0.18^*	?0.36^***	?0.40^***	?0.29^***	?0.33^***	—

Figure 8. Differences in dependent-variable ratings by degree of altruism.
Note: Error bars represent standard errors. ^***p < 0.001.

Figure 9. Moderating effect of self-uncertainty on the relationship between degree of altruism and perceived teaching function.

Table 6 Correlations among variables within the moderate altruism condition

variable	1	2	3	4	5
1. Gender	—	?0.08	?0.15^*	?0.09	?0.01
2. Age	0.01	—	0.11	0.10	?0.02
3. Teaching function	?0.09	0.09	—	0.50^***	0.34^***
4. Morality of the behavior	0.02	0.04	0.59^***	—	0.85^***
5. Moral character	0.04	0.01	0.42^***	0.81^***	—

Table 7 Correlations among variables within the high altruism condition

variable	1	2	3	4	5
1. Gender	—	0.06	?0.06	?0.04	?0.02
2. Age	?0.12	—	0.10	0.05	0.02
3. Teaching function	?0.25^**	0.10	—	0.62^***	0.44^***
4. Morality of the behavior	?0.11	0.08	0.55^***	—	0.86^***
5. Moral character	?0.01	?0.07	0.28^***	0.71^***	—

Figure 10. Differences in dependent-variable ratings by degree of altruism and self-uncertainty.
Note: Error bars represent standard errors. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001, ns = not significant.

Figure 11. Moderating effect of self-uncertainty on the relationship between degree of altruism and perceived teaching function.

Figure 12. Meta-analytic Results.

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