Spatial navigation planning ability relies on both mental imagery and cognitive flexibility. Considering
the importance of planning ability in everyday life, several neuropsychological tests are used in clinical
practice for its assessment, although some of these are not aimed at assessing the strategies of navigational
planning. The Porteus Maze Test (PMT) and the Key Search Task (KST) require to plan a strategy in a maze
and in an imagined space, respectively. To the best of our knowledge, although these two tests share
some features, the relationship between them has never been explored. The purpose of the present study
was to investigate, for the first time, the relationship between the PMT and the KST performances in 38
healthy subjects in order to understand the implications of this association for the assessment of spatial
navigation ability. Subjects were subdivided in bad or good navigation planners on the basis of the their
KST score. The results of the study have revealed a significant difference (t = 2.35; p = 0.03) in the number
of errors made at the PMT by bad navigational planners (0.78±0.28) and good navigational planners
(0.10±0.06). The first group (bad navigational planners) made more errors at the PMT than the good
navigational planners (who made less errors at the PMT). This provides evidence of the possibility to use
the KST and the PMT in a combined way as a new tool for the assessment of spatial navigational planning
ability. Furthermore, this finding highlights the importance of mental imagery and cognitive flexibility
in spatial navigation, suggesting that these functions could be the link between a good planning ability
and a successful spatial navigation. In conclusion, this study suggests that an efficient navigation would
not be possible without a good navigational planning ability