Individual Differences and Sensory Processing
Pediatric PT & OT Services - Seattle, WA
Development of the DIR core capacities can be affected by individual differences in the child. These differences relate to the range and variation in sensory, sensory-motor and motor planning abilities that all children experience. Individual differences affect how we function generally and how our functioning varies depending on the sensory environment in which we find ourselves at a given moment.
Biologically based individual differences are the result of genetic, prenatal, prenatal and maturational variations and/or deficits. They can be characterized functionally as:
- Sensory Modulation including hypo and hyper-reactivity in each sensory modality (sight, sound, touch, taste, smell, pain and vestibular and proprioceptive experience).
- Sensory Processing in each sensory modality (for example, the capacity to decode and comprehend sequences, configurations, and/or abstract patterns in auditory, visual-spatial, and tactile processing, as well as vestibular and proprioceptive - sensory discrimination and motor planning).
- Sensory- affective processing in each modality (for example, the ability to process and react to affect, including the capacity to connect “intent” or affect to motor planning and sequencing, language, and symbols - sensory discrimination and motor planning).
- Motor Planning and sequencing actions to execute one’s intent (motor planning)
A child’s response to touch, movement, visual and auditory stimuli as well as taste and smell can impact them in many ways. It can influence behavior, attention, impulse control, postural control and success in motor control and related functional skills. The sensory systems are our basic source of communication with our environment. The tactile or touch (skin) sensory system has many important functions, including providing us with the ability to know what an object is without looking (tactile discrimination) and identifying temperature and pain. Tactile sensation also plays a crucial role in the development of fine motor abilities and overall body awareness. Movement or the vestibular proprioceptive system consists of parts of the inner ear and related central nervous system structures which perceive and interpret changes in head position. It automatically coordinates movements of one's eyes, head and body. The proprioceptive system provides information related to the muscular and skeletal systems and therefore the position of one's body. These perceptual systems are essential for the development of body awareness and body and space abilities and in perceiving and adapting movement of the body. Vision consists of both the motor function of the eye as well as perception of visual information. The auditory system consists of hearing, speech and language, the child’s response to sound and their ability to perceive the spoken word and follow directions. Taste and smell consists of the child’s response to the stimulus as well as the impact this may have on functions such as eating and response to environments.
Difficulty in the processing and perception of sensory stimuli may affect attention and focus. This can be described as a sensory modulation difficulty. Sensory modulation is the description of the continuum of sensory registration and responsivity that enables one to arouse, alert and attend to stimuli. Within this continuum there is orientation at one end and failure to orient at the other end. Sensory registration with related arousal and attention undergoes normal variation in the course of a day or in an hour in all individuals. It is when the variation is extreme, when an individual spends excessive time at one end of the continuum or the other, or shifts from one extreme to the other, that a problem is indicated. Many children with difficulty in sensory registration and responsivity seem to swing to either or both ends of this continuum (failure to orient or under attend or over orient and over attend). These individuals have difficulty attaining or maintaining the mid-range or selective attention (homeostasis). A child with a sensory modulation difficulty has more frequency and intensity of responses than a typically developing child. This contributes to variation in attention with over or under attention to stimuli in the environment.
- Focused Attention or Homeostasis: The optimum response to sensory stimuli is to maintain an alert, attentive state to focal stimuli in concert with the ability to habituate to or inhibit responses to extraneous stimuli. This is described as homeostasis. When an individual has difficulty in this area of processing sensory stimuli it is described as a sensory modulation disorder. The range of response to sensory stimuli can be from a state of heightened registration or response to low registration or a depressed response. This range includes:
- Defensive >Withdraw (extremely heightened response)
- Defensive > Protective; fight and flight; approach/avoidance (extremely heightened response)
- Defensive > Escalated - giggle; talkative; tangential; intense play; lack safety (heightened response)
- Hyperfocus; overattentive (mildly heightened response)
- Attentive - focused attention to salient stimuli with habituation to extraneous stimuli (homeostasis).
- Lack attention, low registration,, hyporesponsive, excessive habituation - to body, to environment; to cues from those around him (mild to moderate low registration)
- Shutdown (extremely low registration)
- Sensory Defensiveness: The extreme of sensory modulation difficulties is overattention to the point of hypersensitivity. The processing and perception of a sensory stimulus may then contribute to defensive behavior. Sensory defensiveness is a descriptor of the aversive or defensive reactions that one may exhibit to sensory stimuli that is not usually considered noxious or overwhelming. A sensory defensive response is an “emotional” or “visceral” reaction to a stimulus (tactile, auditory, movement, visual, olfactory, and or gustatory) that elicits a “fight and flight” or “protective response” in a child. The child may respond protectively even though he may consciously know that the stimulus is not a threat. This response to a stimulus usually reflects a misinterpretation of sensory events. In some individuals symptoms are subtle, the child may appear to be “fussy”, have a “very definite personal space” or maintain firm restrictions to activities and social interactions in order to avoid offending sensations. In more extreme cases the child may be aggressive in response to a gentle touch, or may cry excessively or withdraw when there is too much noise or activity around them. This can be very challenging as a parent as you may be “walking on egg shells” in anticipation of the next unknown event that may “push your child over the edge.”
It is important to be aware that one’s response can vary during the day, and the response to one type of stimuli can be heightened, while it can be depressed to another. For example a child may be highly sensitive to light touch and hit (fight and flight) in response to your touching him and yet he may be unaware of how high he is when he climbs the railing of the banister (low registration to vestibular stimuli) or a child may be very fearful of movement experiences such as being on an escalator (heightened, approach/avoidance to vestibular), may hyperfocus on the lines in the escalator (overattentive to visual stimuli) as a way of coping with this and may stumble as he moves off the escalator (low registration to change in proprioceptive stimuli).
Sensory Modulation Continuum
- Self-regulation: Self regulation refers to the strategies a child uses to increase their attention to a task, to self calm and for impulse control. During early development, the parent or caregiver in their interaction provides sensory stimulation to the child. This sensitive stimulation (touch, movement, visual and auditory) helps the child develop control, to calm, to attend to salient stimuli and to organize his or her own body. This then contributes to the child developing his or her own strategies to develop control, to calm, to attend to salient stimuli and to organize his or her own body. This enables the child to develop internal regulation and to control of his or her behavior. Thus, self-regulation is the ability to achieve, monitor and change a state of attention and behavior to match the demands of the environment or situation. Self regulation enables the child to initiate and cease activities in relation to the task and situational demands and to comply with a request of another (e.g. parent, teacher or friend).
The child’s regulatory strategies may include tactile (e.g. constantly touching objects, one’s face or hands); visual (e.g. stares out the window, stares at objects in their hand); proprioceptive (e.g. jumps , pushes, bounces, drums; vestibular (e.g. seeks movement in linear planes with pacing, lateral with rocking , or orbital with spinning); auditory (e.g. squeals, hums, repeats directions; oral (e.g. sucks a pacifier, their thumb, a blanket; eats food, chew on objects or their clothing, oral motor overflow); olfactory (e.g. smells or sniffs objects, make comments re smell).
The parent or caregiver may also assist a child with regulatory strategies. These may include tactile (e.g. touches or rubs the child); visual (e.g. exaggerating one’s action to gain the child’s visual attention; drawing a sequence; distracts with visual; provides calming visual objects; avoids settings that are visually “busy”); proprioceptive (e.g. touch pressure, trampoline); vestibular (e.g. swings set at home, rocking chair; auditory (e.g. gives clear verbal cues, verbal warnings; provides structure- “first this then,” sings, avoids settings that are loud; oral (e.g. provides food to chew, pacifier to suck; bottle to suck and comfort); olfactory (e.g. provides objects to smell).
In assessment the methods the therapist used to assist the child to attend or to calm may include tactile (e.g. touch with the palm of the hand, contouring against the body, with the fingers extended and adducted, the thumb extended and abducted; visual (e.g. remain static, use slow movement; proprioceptive (e.g. provide touch pressure, show the child how to hold static positions to decrease the need to constantly move, increase the awareness of the base of support with handling); vestibular (e.g. provide movement in linear , lateral or orbital planes; auditory e.g. wait up to 20 seconds between a comment or request to allow time for processing, expand the vowel in a word to increase attention to the key word, use action words, sing); oral (e.g. provide food to chew or suck; provide a water bottle, provide compression to oral structures); olfactory (e.g. provide objects or aromas to smell).
Sensory Discrimination contributes to the development of motor control and success in functional skills. This depends on the perception of information from a singular sensory system as well as multisensory perception. Efficient sensory discrimination also contributes to the ability to motor plan and sequence. Praxis or motor planning is the ability to conceive of, organize (plan), and carry out or execute an unfamiliar motor activity. Praxis is that ability by which we figure out how to use our hands and body in skilled tasks like playing with toys, using a pencil or fork, building a structure, straightening up a room, or engaging in many occupations. Motor planning is the instinctive "know how" in approaching a novel motor task, the ability to automatically make your body do what you want it to do, without having to consciously think out every step of the task. The child's ability to accurately perceive and process sensory information from his body's interaction with the environment is essential for motor planning. The components of motor planning include: ideation, motor sequencing, motor innovation and adaptability. Ideation has a strong cognitive component and requires the ability to associate previously experienced activities with what is currently presented. Motor sequencing, which reflects the child's ability to determine what action needs to be done first, second and third in order to achieve success with a motor task, depends on an adequate sense of body scheme. Motor execution impacts the quality of one's motor planning. Mild hypotonia as well as poor cocontraction and balance difficulties impact the quality of motor execution and, therefore, motor planning. Finally, adaptability is essential in being able to generalize and adjust a motor plan based on the changes that occur within the environment. Development of independence in functional skills such as dressing skills, fine motor abilities such as pencil use, manipulation of toys and eating utensils and gross motor skills such as bike riding and climbing reflect a child=s sensory discrimination and motor planning .
Functional skills impacted by sensory discrimination and motor planning difficulties include dressing skills, fine motor abilities such as pencil use, manipulation of toys and eating utensils and gross motor skills such as bike riding, climbing and other age appropriate skills. Organization, approach to tasks and following directions contributes to success with functional skills.
To understand each child’s individual differences it is essential to have a clear understanding of the child’s sensory profile. This includes sensory modulation, sensory processing and sensory- affective processing :
The child who is under responsive is slow to respond to a sensory stimulus and will require high intensity or increased duration to invoke an observed behavioral response. The child may have: a diminished response (behaving in accordance with their threshold)
sensory seeking behavior (behaving to counteract their threshold).
This is the child whose behavior suggests that he or she has:
a diminished perception of sensory input from his or her body,
a “hazy” perception of his or her body (a “Novocain” sensorimotor cortex) which may contribute to a diminished perception of him or herself as he or she moves and interact.
The child who is over responsive to sensory stimuli has quick or intense response that result in:
exaggerated responses (fight or fright)
or withdrawal (flight or freeze)
This is the child whose behavior suggests that he or she has:
an intense and often scattered perception of sensory input from his or her body, a “firecracker” perception of his body in his sensorimotor cortex that contributes to an exaggerated but scattered perception of him or herself as he or she moves and interact.
In therapy, in the home during activities of daily living and during social interaction and in the school setting it is essential to interact and handle the child who has difficulties or gaps in these six core capacities of development in ways that are sensitive to his or her sensory profile. As one interacts with the child one should be aware of the power of affect and physical actions but we always need to constantly aware of the child’s underlying sensory profile.
- The child who is under responsive responds to activities that are stimulating for them. Affect should be “up”, enticing the child with expressive facial expression, gesture and language. As the child is bathed in affect, the physical piece of the interaction should also be “up” with the focus on increasing the child’s sense of their body, with the goal to increase their sense of their “body map”.
- The child who is over responsive responds to activities that provide a clear localized sense of their body. Affect should be “soothing” with the focus on “down regulation”. Facial expression, gesture and language should be clear, with rhythm and predictability.
- Some children who are under responsive seek input but quickly become escalated as they experiences the stimulation that they seek in a disorganized manner. As we interact we need to constantly be in tune with the child and adapt our interaction with the child and to change affect and physical interaction as the child changes in his response.