CONTENTS
I. Interests, opportunity and materials
II. Observational problems and methods
III. Results of multiple-choice experiments:
1. Skirrl, Pithecus irus 2. Sobke, Pithecus rhesus 3. Julius, Pongo pygmaeus
IV. Results of supplementary tests of ideational behavior:
1. Julius, Pongo pygmaeus:
Box stacking experiment
Box and pole experiment
Draw-in experiment
Lock and key test
2. Skirrl, Pithecus irus:
Box stacking experiment
Box and pole experiment
Draw-in experiment
Hammer and nail test
Other activities
3. Sobke, Pithecus rhesus:
Box stacking experiment
Draw-in experiment
Box and pole experiment
Other activities
V. Miscellaneous observations:
1. Right- and left-handedness
2. Instinct and emotion:
Maternal instinct
Fear
Sympathy
VI. Historical and critical discussion of ideational behavior in
monkeys and apes:
1. Evidences of ideation in monkeys
2. Evidences of ideation in apes
VII. Provision for the study of the primates and especially the monkeys
and anthropoid apes
VIII. Bibliography