What is Sensory Processing Disorder (SPD)?

Sensory processing disorder

How our brain processes information in Sensory Processing Disorder

Information about what our bodies are doing comes into our brain from our commonly known senses (sight, touch, hearing, taste, smell) and also from our less commonly known senses (balance and body awareness).

The brain then processes the information and directs the body to produce a response that is appropriate to the situation. 

This process is known as Sensory Modulation.


In Sensory Processing Disorder (SPD), the brain gets the processing aspect ‘mixed up’ so the response then cannot be appropriate. For example, when we put on our clothes, touch sensory information is sent to our brain which the brain usually processes as ‘not important/not threatening’ and so usually the body does not need to react.

However, in Sensory Processing Disorder, the brain may process the touch information from the clothing as ‘urgent/ threatening’ and therefore the person may have an extreme or over reaction.

In other instances, the brain of a person with Sensory Processing Disorder may under-respond to sensory information, for example a sound (like someone calling their name), so the person does not react appropriately or under react.

Children (or adults) with Sensory Processing Disorder (SPD) therefore may have difficulties with attention, emotional regulation or avoid certain activities such as tooth brushing, nail cutting, particular foods, noisy places etc.

Sensory processing difficulties are also common in other conditions such as Autism, and ADHD.

Sensory processing disorder

What kind of behaviours are common in children with sensory processing difficulties?

Children’s (and adult’s) sensory systems (and modulators!) are all different, so our behaviour when too many messages come in (over-alertness) or not enough messages come in (under-alertness) varies. However, there are some behaviours that are more common.

Sensory processing disorder

When over alerted (modulator stressed), children may...

Sensory processing disorder

When under alerted (modulator asleep), children may...

How do I know if my child definitely has Sensory Processing Difficulties?

Usually an Occupational Therapist, Speech and Language Therapist or Physiotherapist trained in Sensory Integration will confirm Sensory Processing Difficulties/Disorder. However ideally, a full team assessment (including the Sensory Integration trained therapist), is most useful.

Other issues such as poor eyesight, learning disabilities, genetic abnormalities, poor hearing, low muscle tone, and emotional issues can cause behaviours that may seem to be due to poor sensory processing, therefore all these factors need to be considered before making the final diagnosis.

Also, as Sensory Processing difficulties are common in conditions such as Autism an ADHD, other diagnoses where Sensory Processing difficulties are part of (not separate to) the condition need to be considered. This can best be done by a multi-disciplinary team assessment.

How can I explain sensory processing difficulties to my child?

‘Max and Me, a story about sensory processing’ is the first book which describes the neurology (what’s happening in the brain) in Sensory Processing Disorder (SPD)  not just the behavioural responses.

‘Max and Me’ was written completely jargon- free so that children could understand the story themselves.

The story is also fully illustrated to help those with limited language to follow the story line.

The idea with the book is that the whole family can talk about their own sensory processing or 'modulators' so the child does not feel isolated or unusual.

Behaviour is explained by how the modulator is feeling so the child does not feel to blame.