Tolman's Sunburst Maze 80 Years on: A Meta-Analysis Reveals Poor Replicability and Little Evidence for Shortcutting

The Sunburst maze, first described 80 years ago by Tolman, Ritchie and Kalish (1946) and popularized by Tolman (1948), is widely regarded as a classic demonstration of cognitive map use in rats. In this task, animals trained on a circuitous path to a reward were presented with new paths, including a shortcut, after the original route was blocked. A substantial proportion of rats selected the shortcut, which Tolman et al. (1946; 1948) interpreted as evidence that animals have an internal spatial representation, or 'cognitive map'. Despite the influence of this study, attempts to replicate it have been largely unsuccessful. This review critically examines a dozen replications involving rats, squirrel monkeys and humans, highlighting a range of alternative strategies, with only a fraction of experiments demonstrating shortcutting (17%). Instead, most studies found that animals either favoured paths adjacent to the original training route (32%), did not have a preference (26%), chose unremarkable paths (13%) or selected options consistent with previously rewarded responses (6%), suggesting a reliance on procedural or associative learning rather than demonstrating flexible spatial inference. Although the original experiment has been widely criticized for including a visual cue above the reward location, subsequent studies rarely found that this feature guided path choices (6%). Neurophysiological data from hippocampal lesion and head-direction cell studies further undermine the claim that shortcutting in the Sunburst maze depends on cognitive maps. We argue that this study, though historically significant, is a poor standalone demonstration of map-based navigation.