Autism is a perplexing condition because of its unique presenting signs and high degree of variability. Evidence is presented that the basic underlying information processing disorder is a dysfunction of the appreciation of the emotional significance of incoming stimuli and attaching motivational value to the stimuli. It is proposed that this dysfunction occurs when the amygdaloid nucleus and/or its connections are disrupted, resulting in the variability of the presentation of this syndrome among individuals. Herpes simplex encephalitis sometimes results in signs of autism. The virus has a predilection to attack specific areas of the brain, which provides information on the probable underlying neurological dysfunction in autism.