For the senses to work properly a huge amount of sensory processing has to take place in a very short space of time and that timing of the information flow is of critical importance. If the brain does not discard enough information, we may get overloaded by the sheer amount of input. If the brain does not scan our memory banks fast enough, our life may be in danger. If our memory banks are inaccurate because we had distorted input in the past, we may have difficulty in recognising things or be unable to make connections between perceived objects and their likely behaviour.

Prior to processing useful information our brain first has to decide what information is useful. The brain has to manage enormous flows of information coming in from the senses and has to be very efficient at discarding most of that information.

Help For Sensory Overload

Help For Sensory Overload

Our mind only has a certain capacity to process and use information. The processing power is huge, but the conscious mind has a very limited capacity. In other words, we can only consciously think of and manage very few things at the same time. Actually, we probably can only think of one thing at a time, but we do have the capacity to very quickly switch between a few subjects, each one in turn, one after another. When we express the capacity of our conscious mind into computer terms, it is very small indeed. Scientists believe that the capacity of our conscious mind is less than 100 bits per second. It’s not really important to understand what that means, but it is very important to understand what the incoming flow of information is, expressed in the same terms:

  • Eyes (vision): 10,000,000 bits per second
  • Ears (hearing): 100,000 bits per second
  • Skin (touch): 1,000,000 bits per second
  • Nose (smell): 100,000 bits per second
  • Mouth (taste): 1,000 bits per second

Data Source: The User Illusion: Cutting Consciousness Down to Size (Penguin Press Science) Tor Norretranders (Author) ISBN: 0-14-023012-2. p.143

Thus, in total we receive through our five senses more than 11 million bits of information each second of the day, while our conscious mind can only deal with one subject at a time at a rate of less than 100 bits per second. That’s another very good reason why we need our brain to process the information from our senses, as we would go mad (and we mean that literally) if all that information came straight to our conscious mind.

If our conscious mind can only deal with less than 0.001 % of all information coming in, just imagine how overwhelming the world must appear to people who cannot filter out sufficient information. Over-sensitivity of one or more of the senses is not only being able to hear, see, feel, smell or taste more, but often is also linked to receiving more information than we are able to deal with. Such a bombardment of information will lead rapidly to stress and discomfort, often leading to the person ‘switching off’ or ‘tuning out’ from the outside world. In short, the processing of our sensory input is vital to our survival and slight difficulties in that processing can lead to significant learning and developmental difficulties.

All our sensory information requires processing, but in the following part we will concentrate on auditory and visual processing, the processes of recognising and interpreting information taken in through the ears and eyes. Auditory and visual processing deficiencies are commonly linked to learning difficulties and since much information is presented verbally or visually, a person with an auditory or visual processing disorder will be at a great disadvantage. Some of the more common auditory and visual processing difficulties are listed below.

Auditory processing difficulties impact on an individual’s ability to analyse and make sense of information taken in through the ears. This is different from problems involving hearing, such as deafness or being hard of hearing. Difficulties with auditory processing do not affect what is heard by the ear, but do affect how this information is interpreted and processed by the brain.

An auditory processing difficulty will directly impact on speech and language and will affect other areas of learning, especially reading and spelling. Instructions often rely on the spoken word and a person with an auditory processing difficulty may find it very hard to understand the learning points or specific instructions.

Common areas of auditory processing difficulties are:

  • Phonological awareness is the ability to recognise that language is made up of individual sounds, called phonemes, which are put together to form the words we speak. Reading, writing and understanding spoken language all depend on the ability to recognise or isolate individual sounds in a word, to identify similarities between words and to be able to hear the number of sounds in a word.
  • Auditory discrimination is the ability to recognise differences in phonemes, or sounds, including the ability to identify words and sounds that are similar or which are different.
  • Auditory memory is the ability to store and recall information which was received through the ears. Inability to remember or recall information rapidly will influence the ability to follow verbal instructions or follow a storyline.
  • Auditory sequencing is the ability to remember and reconstruct the order of sounds in a syllable or word, or the order of items in a list. One example is saying or writing “hostipal” for “hospital”.
  • Auditory blending is the process of putting together phonemes to form words. For example, the individual phonemes “d”, “o”, and “g” are blended to form the word “dog”.

Visual processing difficulties refer to a lessened ability to make sense of information taken in through the eyes. This is different from problems involving sight or sharpness of vision. Difficulties with visual processing affect how visual information is interpreted or processed by the brain.

Common areas of visual processing difficulties are:

  • Spatial Relationships. This refers to the position of objects in space and the ability to accurately perceive objects in space with reference to other objects. Reading and mathematics are two subjects where accurate perception and understanding of spatial relationships are very important. Both subjects rely heavily on the use of symbols, such as letters, numbers, punctuation and mathematical signs. Examples of how difficulties with spatial relationships may interfere with learning are in being able to perceive words and numbers as separate units, directional difficulties in reading and mathematics, confusion of similarly shaped letters, such as b and d, or p and q. Being able to perceive elements in relation to each other is a key skill in mathematics and in order to be successful, the child must be able to associate that certain digits go together to make a single number. A 2 next to a 4 makes 24, but other digits may be single numbers, the operational signs, like +, -, x, =, are distinct from the numbers and reveal the relationship between them. The only cues in a mathematical formula are the spacing and order between the various symbols. The ability and understanding of spatial relationships is paramount to perform well in mathematics.
  • Visual discrimination is the ability to distinguish objects based on their individual visual characteristics. Visual discrimination is vital in the recognition of common objects and symbols. We identify different objects by recognising shape, form, pattern, position, size and colour. Visual discrimination also refers to the ability to separate an element from its surrounding environment. Visual discrimination difficulties can diminish the ability to accurately identify symbols, obtain information from pictures, graphs or charts, and be able to use visual materials in a productive way. The ability to recognise distinct shapes from their background, such as letters on a blackboard or objects in a picture is largely a function of visual discrimination.
  • Visual closure is the ability to identify or recognise an object or symbol when part of the object is not visible. A person with visual closure difficulties may, for instance, not be able to recognise a drawing of a face when just one element is missing, for instance a drawing of a face without a nose will fall into many possible categories, such as a possible ball, balloon, full moon, or round plate, leading to processing overload and failure to recognise the drawing.
  • Object Recognition. Some people are unable to make the link between objects they see and the objects stored in their visual memory. This can be because the object seen through the eyes is processed incompletely or in a distorted way and thus does not match any visual memories, or because the visual memory is incomplete or distorted, or because the visual memory is poorly organised, or any combination of these factors.

Whole/Part Relationships

When people learn to read, they start by combining the sounds of individual letters into a single word, and later they progress by remembering each individual word in a sentence to make sense of the whole. Most adults can scan long complex words and phrases and see them as a single entity with a particular meaning, but some will only be able to recognise the individual elements and find it difficult to put them all together. For instance the phrase “The greenhouse effect” has four key elements, “the”, “green”, “house” and “effect”. Individually these elements may make sense to someone, while the overall meaning may not be perceived. For some other tasks it is important to be able to separate complex objects into individual components. A more complex mathematical formula can only be solved by breaking it down into the right elements in the right order. To write good prose or learn a foreign language we have to be able to recognise the elements that make up a sentence. People that have difficulties in perceiving the whole will often get lost in detail and may have difficulties in spacing out writing on a page. People that can only perceive the whole will have great difficulty in solving complex problems and in perceiving relationships between component parts.

All senses rely on a significant amount of processing in the brain to ensure the input makes sense to us. It is often the processing part that has the deficiencies in a particular sense and fortunately the processing part is the easiest to re-train. Most of our interventions are based on re-training how information from the senses is processed and through this instigating changes in ability, behaviour and performance.


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