This theory proposes that an infant’s cry conveys the degree of the infant’s distress or state of arousal, but not its specific cause. It contrasts with the idea of ‘cry types‘, where the audible, acoustic features of a cry are assumed to vary so as to signal its particular cause (e.g., ‘hunger’ versus ‘anger’ versus ‘pain’ cries). According to graded signal theory, parents and others use contextual information to work out the cause.
See Arousal, Behavioral state, Crying, Crying peak, Fussing