self-concept exhibited greater ingroup biases than did people with low self-esteem who suffered a threat to the self-concept. While some studies have supported this notion of a negative correlation between self-esteem and in-group bias, other researchers have found that individuals with low self-esteem showed more bias toward both in-group and out-group members. Some studies have even shown that high-self-esteem groups showed more bias than did lower self-esteem groups. This research may suggest that there is an alternative explanation and additional reasoning as to the relationship between self-esteem and in-group/out-group biases. Alternatively, it is possible that researchers have used the wrong sort of self-esteem measures to test the link between self-esteem and in-group bias (global personal self-esteem rather than specific social self-esteem). Biological basis as an effect of oxytocin In a meta-analysis and review of the effect of oxytocin on social behavior done by Carsten De Dreu, the research reviewed shows that oxytocin enables the development of trust, specifically towards individuals with similar characteristics—categorized as 'in-group' members—promoting cooperation with and favoritism towards such individuals. This bias of oxytocin-induced goodwill towards those with features and characteristics perceived to be similar may have evolved as a biological basis for sustaining in-group cooperation and protection, fitting with the Darwinian insight that acts of self-sacrifice and cooperation contribute to the functioning of the group and hence improve the odds of survival for members of said group. Race can be used as an example of in-group and out-group tendencies because society often categorizes individuals into groups based on race (Caucasian, African American, Latino, etc.). One study that examined race and empathy found that participants receiving nasally administered oxytocin had stronger reactions to pictures of in-group members making pained faces than to pictures of out-group members with the same expression. This shows that oxytocin may be implicated in our ability to empathize with individuals of different races, with individuals of one race potentially biased towards helping individuals of the same race than individuals of another race when they are experiencing pain. Oxytocin has also been implicated in lying when lying would prove beneficial to other in-group members. In a study where such a relationship was examined, it was found that when individuals were administered oxytocin, rates of dishonesty in the participants' responses increased for their in-group members when a beneficial outcome for their group was expected. Both of these examples show the tendency to act in ways