Aggregated Cognitive Assessments and the Limits of Discriminative Evaluation

This technical note examines the limitations of aggregated cognitive assessments commonly used to summarize performance across tasks or domains. By isolating a minimal condition under which aggregation collapses distinct cognitive profiles into identical scores, it shows how discriminative information may be lost despite locally informative evaluations. The analysis is purely diagnostic and non-theoretical, focusing on inferential limits imposed by evaluation interfaces rather than on cognitive models or psychological interpretations.