Many of the symptoms associated with the different types of autism spectrum disorder are behavioural and only by studying them may it be possible for a professional to determine which disorder an individual has. Sometimes this might be an inability to grasp concepts or to interact socially in certain situations. Abnormal reactions to sounds, touch or sights can also be a common behavioural symptom of the spectrum, too. Developmental symptoms include things like children who don't respond to their name or failing to engage with people's faces, especially when interacting one-on-one. Many people with an autism spectrum disorder will show it in how they speak. Rigid use of a language and sticking to a single topic in a monologue fashion are common linguistic traits.