Table 1 Overview of the results.

Values indicate the number of trials in which the functional item was selected or used. The numbers in parentheses indicate the maximum possible number of successes. Each subject’s individual performance in selecting the functional item was significant in all experiments (exact binomial test). N.A., not tested.

Experiment 1: 15-min delay
Tool conditionBartering condition
SubjectSelectedUsedSelectedUsed
Rickard (male)14 (14)12 (14)36 (36)29 (36)
Siden (male)N.A.N.A.36 (36)21 (36)
Juno (female)14 (14)12 (14)36 (36)31 (36)
None (female)11 (14)8 (11)35 (36)30 (35)
Embla (female)11 (14)11 (11)N.A.N.A.
Experiment 2: 17-hour delay
Tool conditionBartering condition
SubjectSelectedUsedSelectedUsed
Rickard (male)6 (6)6 (6)6 (6)6 (6)
Siden (male)N.A.N.A.6 (6)6 (6)
Juno (female)5 (6)5 (5)6 (6)5 (6)
None (female)N.A.N.A.6 (6)6 (6)
Embla (female)6 (6)5 (6)N.A.N.A.
Experiment 3: Self-control long delay
Tool conditionBartering condition
SubjectSelectedUsedSelectedUsed
Rickard (male)12 (14)12 (12)12 (14)10 (12)
Siden (male)N.A.N.A.11 (14)11 (11)
Juno (female)8 (14)7 (8)11 (14)10 (11)
None (female)N.A.N.A.7 (14)6 (7)
Embla (female)11 (14)11 (11)N.A.N.A.
Experiment 4: Self-control short delay
Tool conditionBartering condition
SubjectSelectedUsedSelectedUsed
Rickard (male)14 (14)14 (14)14 (14)14 (14)
Siden (male)N.A.N.A.14 (14)14 (14)
Juno (female)14 (14)14 (14)14 (14)14 (14)
None (female)N.A.N.A.14 (14)14 (14)
Embla (female)14 (14)14 (14)N.A.N.A.