APA Dictionary of Psychology

a clinical, behavioral, or neurological sign that may reflect the presence of neurological impairment. Soft signs are subtle, nonspecific, and ambiguous (because they are also seen in individuals without neurological impairment). Examples include slight abnormalities of speech, gait, posture, or behavior; sleep disturbances; slow physical maturation; sensory or perceptual deficits; and short attention span. Also called equivocal sign; soft neurological sign.