havior (e.g., repetitive questioning, pacing a perimeter). Highly restricted, fixated interests
in autism spectrum disorder tend to be ab normal in intensity or  focus (e.g., a toddler
strongly attached to a pan; a child preoccupied with vacuum cleaners; an adult spending
hours writing out timetables). Some fascinations and routines may relate to apparent hy-
per- or hyporeactivity to sensory input, ma nifested through extreme responses to specific
sounds or textures, excessive smelling or touc hing of objects, fascination with lights or
spinning objects, and sometimes apparent indi fference to pain, heat, or cold. Extreme re-