Abstract: The string-pulling test is one of the most widely used behavioral approaches in comparative psychology research on animals, including birds, mammals, and invertebrates. Exploring the process by which animals obtain rewards such as food by string pulling can assess their understanding of spatial and causal relationships. Here, we summarize the methods of string-pulling in animals, the patterns and characteristics of string-pulling in different animal groups, and the underlying cognitive mechanisms. Two different methods were used in the animal string-pulling test, including side-stepping (one-side limb pulling string) and double-stepping (staggered pulling string with both limbs). In the tests, strings were mostly arranged in horizontal or vertical directions. Different numbers and arrangements of strings could be presented to animals to understand the underlying cognitive mechanisms. In animal string-pulling tests, the main mechanisms involved congenital behavior, the proximity principle, trial-and-error learning, means-end understanding, and perceptual feedback. String-pulling test is an important method for studying animal cognition, which helps improve the understanding of animal cognition.

Key words: string-pulling test, animal cognition, means-end, perceptual feedback