Fig 5. Signal, noise and principal angle.

A. Signal (which for linear information is the norm of the difference in the mean responses in the two conditions, i.e. the norm of w = μ₂−μ₁) for the What condition, after projecting data into each subspace. The subspace for a single block is given by activity in the two time bins (i.e. 0–250 ms after cue onset and 251–500 ms after cue onset). B. Same as A for the Where condition. C Noise (Trace of the noise covariance matrix, after projecting data into corresponding subspace) for the What condition. D. Same as C for the Where condition. E. Principal angles for the What condition. This is the angle between the subspace for the current block and the opposite phase of the current block (x-phase), other blocks of the same type (x-block) and other blocks of the other type (x-cond). Note the principal angle is given by the matrix norm of the matrix of dot products between all dimensions of each subspace. F. Principal angles for the Where condition. The principal angle is larger between subspaces for different blocks of the What condition than the where condition.