Table 2.

Testing scheme

Bird/group	S+	S−	Probes
729/1	/dit/1	/dUt/1	/dIt/1 and /dut/1
728/2	/dUt/2	/dit/2	/dIt/2 and /dut/2
750/3	/dit/3	/dUt/3	/dIt/3 and /dut/3
763/4	/dUt/4	/dit/4	/dIt/4 and /dut/4
734/5	/dIt/1	/dut/1	/dit/1 and /dUt/1
731/6	/dut/2	/dIt/2	/dit/2 and /dUt/2
758/7	/dIt/3	/dut/3	/dit/3 and /dUt/3
741/8	/dut/4	/dIt/4	/dit/4 and /dUt/4

This table shows which tokens of which stimuli were presented as either negative or positive stimulus to individual birds and groups of human participants. S+, positive stimulus; S−, negative stimulus