Na n'ime-achị aghụghọ, na aka nke ọzọ, omume nke sonyere na-tụnyere tupu mgbe ọgwụgwọ (Greenwald 1976; Charness, Gneezy, and Kuhn 2012) . 
Na n'ime-achị aghụghọ, na aka nke ozọ, omume nke sonyere na-tunyere tupu mgbe ọgwugwọ (Greenwald 1976; Charness, Gneezy, and Kuhn 2012) . 