Supplementary Material for: The Single-Matrix Digit Cancellation Test (SMDCT), a screener for selective attention deficits: standardization in an Italian population sample and clinical usability in acute stroke patients

Introduction. This study aimed at validating and providing Italian norms for the Single-Matrix Digit Cancellation Test (SMDCT), a cancellation task to screen for selective attention deficits, as well as providing clinical usability evidence for it in acute stroke patients. Methods. The SMDCT stimulus is a specular, 4-quadrant, horizontally oriented matrix, across which target distribution is homogeneous. Both Accuracy (-A) and Time (-T) outcomes were computed. N=263 healthy participants (HPs) and N=76 acute stroke patients were recruited. N=108 HPs also underwent the Mini-Mental State Examination, Frontal Assessment Battery (FAB) and Trail-Making Test (TMT), whilst patients were further assessed via the Mental Performance in Acute Stroke (MEPS). Regression-based norms were derived (Equivalent Scores). Construct and factorial validity, as well as case-control discrimination, were tested. Results. The matrix was underpinned by a two-component structure reflecting left and right hits. The SMDCT-T and -A were associated with TMT and FAB scores, respectively. Education predicted the SMDCT-A/-T, whereas age the SMDCT-T only. In patients, the SMDCT converged with the MEPS, also accurately discriminating them from HPs. An index of right-left difference differentiated right- from left-damaged patients. Conclusions. The SMDCT is a valid and normed screener for selective attention deficits, encompassing measures of both accuracy and time, whose adoption is encouraged in acute stroke patients. Relatedly, the horizontal disposition of its matrix does allow for the qualitative report of either leftwards of rightwards biases due to underlying visual or attentional-representational deficits in this population.