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Updated: Apr 17, 2026
Progressive-ratio Responding for Palatable High-fat and High-sugar Food in Mice
Published on: May 3, 2012
The progressive digging task: A naturalistic assay of effort-based food motivation in mice
Karla Mendez Vasquez1, Jacob Calle1, Milo Duch1
1Western Connecticut State University, Department of Biology, 181 White Street, Danbury, CT 06810, USA.
Background:
The progressive ratio (PR) task is a widely used measure of effort-based food motivation, but it relies on operant conditioning rather than natural behaviors.
New Method:
Here, we developed a progressive digging (PD) task that leverages the natural foraging behavior of mice to assess food motivation. In the PD task, mice retrieve a buried food reward by digging through progressively deeper layers of bedding, and the total amount of bedding displaced across trials serves as the primary measure of effort. We validated the PD task by testing the same male C57BL/6 N mice under fed and fasted conditions in both PD and PR tasks.
Results:
Effort was stable across repeated fed (baseline) testing for both tasks, indicating consistent performance. Baseline effort in the PD task showed a moderate, non-significant correlation with baseline effort in the PR task. Following a 12-h fast, effort significantly increased in both tasks, with the PD task showing a substantially larger increase than the PR task.
Comparison With Existing Methods:
These findings indicate that the PD task is a reliable and sensitive measure of effort-based food motivation that complements the PR task.
Conclusions:
By capturing a natural foraging behavior, digging, the PD task may offer enhanced sensitivity for detecting changes in motivation, making it a powerful tool for preclinical studies investigating the neurobiology of motivated behavior.
