Sparse spatial scaffolding for visual working memory

When holding information in mind, it is vital to keep individual representations separated and selectively accessible for behaviour. Space is known to serve as a foundational scaffold for mnemonic individuation, yet the format and flexibility of spatial scaffolding for working memory remain elusive. We hypothesised that information in working memory can be re-coded from its native format at encoding to organise and retain internal representations sparsely. To test this, we presented to-be-memorised visual objects at distinct directions and distances and leveraged gaze biases during mnemonic selection as an implicit read-out of spatial scaffolding for working memory. We report how the human brain abstracts away over incidental object distance when direction alone suffices as a scaffold, but incorporates distance when it aids mnemonic individuation. This unveils the principle of sparse spatial scaffolding for working memory, whereby the human brain flexibly resorts to the minimal spatial scaffold needed for the individuation of internal representations.