Selective attention for state representation. Consider a representational space for the task of making tea, defined along four dimensions: Water temperature (hot/cold), Mug material (glass/metal), Sugar (yes/no), and Tea (yes/no), each involving, for simplicity, a binary feature. The top row depicts how the number of states grows as we add dimensions. Considering only one dimension (Water) results in two possible states (a). Two dimensions would mean four states (b), three dimensions eight states (c), and four dimensions would mean 16 unique states (d). This exponential increase in the number of states as the number of dimensions grows is known as the curse of dimensionality. The bottom row shows how selective attention can solve this problem: ignoring even one dimension (Mug) reduces the size of the state space by a factor of two.