Table 3.

Comparison of previous studies of inequity completed at Yerkes (Brosnan et al. 2005), Leipzig (Bräuer et al. 2006, 2009) and Bastrop (current study)

	Yerkes			Leipzig		Bastrop
	Long-term	Short-term	Pair-housed	Bräuer et al. 2006	Bräuer et al. 2009	Males	Females
Group stability (years)	30	8	Variable	6	6+*	30+
Social group	Multimale, multifemale		Pair-housed	Multimale, multifemale		Multimale, multifemale
Individuals tested	1 M, 9 F	4 M, 2 F	2 M, 2 F	13, sex not reported	2 M, 4 F	10 M, 6 F
Tests	ETLV, IT, FC			ETLV, ETHV, IT	ETLV, IT	ETLV, ETHV, FC, IT, GR, DT, DETLV, DETHV
Task	Exchange			None	Exchange	Exchange
Orientation	Side by side			Across†	Across†	Side by side
Physical interaction	Yes			No (separated)†	No (separated)†	Yes
Social contrast	No	Yes	Yes	No	No	Yes	No
Individual contrast	No	No	No	No	No	No	Yes
Effect of rank	No	No	No	Yes‡	No	Yes	Yes

ETLV: equity test, low value; ETHV: equity test, high value; FC: food control; IT: inequity test; GR: gift reward; DT: delay test; DETLV: differential exchange test, low value; DETHV: differential exchange test, high value. See Table 1 for details of each test.

^*Estimated from Bräuer et al. (2006).

^†Based on the description provided, chimpanzees were in separate enclosures, separated by a booth approximately 1 m wide. Rewards were presented in the booth, so chimpanzees interacted while facing each other through the windows in the booth.

^‡High-ranking chimpanzees were more likely to ignore food and leave the experimental area, but this behaviour did not differ between conditions of equity and inequity.