suggested combining the two factors. Restricted interests: Interests or fixations that are abnormal in theme or intensity of focus, such as preoccupation with a single television program, toy, or game. Self-injury: Behaviors such as eye-poking, skin-picking, hand-biting and head-banging. Self-injury Self-injurious behaviors (SIB) are relatively common in autistic people, and can include head-banging, self-cutting, self-biting, and hair-pulling. Some of these behaviors can result in serious injury or death. Following are theories about the cause of self-injurious behavior in children with developmental delay, including autistic individuals: Frequency and/or continuation of self-injurious behavior can be influenced by environmental factors (e.g. reward in return for halting self-injurious behavior). However this theory is not applicable to younger children with autism. There is some evidence that frequency of self-injurious behavior can be reduced by removing or modifying environmental factors that reinforce this behavior. Higher rates of self-injury are also noted in socially isolated individuals with autism. Studies have shown that socialization skills are related factors to self injurious behavior for individuals with autism. Self-injury could be a response to modulate pain perception when chronic pain or other health problems that cause pain are present. An abnormal basal ganglia connectivity may predispose to self-injurious behavior. Other features Autistic individuals may have symptoms that do not contribute to the official diagnosis, but that can affect the individual or the family. Some individuals with ASD show unusual or notable abilities, ranging from splinter skills (such as the memorization of trivia) to rare talents in mathematics, music or artistic reproduction, which in exceptional cases are considered a part of the savant syndrome. One study describes how some individuals with ASD show superior skills in perception and attention, relative to the general population. Sensory abnormalities are found in over 90% of autistic people, and are considered core features by some. More generally, autistic people tend to show a 'spiky skills profile', with strong abilities in some areas contrasting with much weaker abilities in others. Differences between the previously recognized disorders under the autism spectrum are greater for under-responsivity (for example, walking into things) than for over-responsivity (for example, distress from loud noises) or for sensation seeking (for example, rhythmic movements). An estimated 60–80% of autistic people have motor signs that include poor muscle tone, poor motor planning, and toe walking; deficits in motor coordination are pervasive across ASD and are greater in autism proper. Pathological demand avoidance can occur. People