Failure to function - inability to manage the demands of daily life. This failure manifests in an inability to maintain basic standards of nutrition and hygiene, sustain employment, or nurture relationships. Rosenhan and Seligman added criteria for identifying inadequate coping, including deviation from standard interpersonal norms, experiencing severe personal distress, or displaying irrational or harmful behaviour. Consideration of intellectual disability disorder illustrates how a diagnosis depends not only on statistical infrequency, like a low IQ, but also on inadequate functioning.