The meaning of sensory integration
Sensory integration is the ability to take in information through the senses of touch, movement, smell, taste, vision, and hearing, and to combine the resulting perceptions with prior information, memories, and knowledge already stored in the brain, in order to derive coherent meaning from processing the stimuli. The mid-brain and brain stem regions of the central nervous system are early centers in the processing pathway for sensory integration. These brain regions are involved in processes including coordination, attention, arousal, and autonomic function. After sensory information passes through these centers, it is then routed to brain regions responsible for emotions, memory, and higher level cognitive functions.
Hyposensitivities and Hypersensitivities
Sensory integration disorders vary between individuals in their characteristics and intensity. Some people are so mildly afflicted the disorder is barely noticeable, while others are so impaired they have trouble with daily functioning.
Kids can be born hypersensitive or hyposensitive to varying degrees and may have trouble in one sensory modality, a few, or all of them. Hypersensitivity is also known as sensory defensiveness. Examples of hypersensitivity include feeling pain from clothing rubbing against skin or an inability to tolerate normal lighting in a room. This oversensitivity can cause people to prefer not to be touched or caressed, or to refrain from looking directly into the eyes of another person.
An example of a child or adult with hyposensitivity is one who throws themselves into a wall in order to get a sense of their body.
Sensory integration and autism spectrum disorders
Sensory integration dysfunction is a common symptom of autism . Often, autistic children receive too much sensory stimulation through one or more of their senses, and in order to turn down the volume, they tend to avoid people, noises and bright lights. Autistic children do not develop the neurotypical capacity to integrate and modulate information from the five senses.
In her book, Thinking in Pictures, Temple Grandin reports the results of a survey about sensory integration in a relatively small population with autism spectrum disorders from one center:
“A survey of sensory problems in 30 adults and children was conducted by Neil Walker and Margaret Whelan from the Geneva Centre for Autism in Toronto. Eighty percent reported hypersensivity to touch. Eighty-seven percent reported hypersensivity to sound. Eighty-six percent had problems with vision. However, thirty percent reported taste or smell sensitivities.”
Not everybody agrees with the notion that hypersensitive senses is necessarily a disorder. Even if hypersensitivity is the most common in autism, insensitivity to pain is also common. Additionally, there is no proof for the idea that hypersensitivity would necessarily be a result of sensory integration issues.
It is possible that misdiagnosis is also a problem with the construct of Sensory Integration Dysfunction. Some experts claim that Occupational Therapists incorrectly apply this label to individuals with attention difficulties or who simply don’t put forth any effort during assessments. For example, a student who fails to repeat what has been said in class (due to boredom or distraction) is referred for evaluation for sensory integration dysfunction. The student is asked to listen to signals coming from either side of a pair of headphones and combine them to form words. The student is still bored or distracted, and so does poorly on the test. The assessor concludes that the student has sensory integration dysfunction, while, in fact, he may have a disorder of auditory processing (also over-diagnosed , poor auditory attention, a mood problem, or may fail to put forth adequate effort on the task for other reasons. Diagnoses based on single tests are unreliable, and integrated assessment utilizing multiple sources of information is the preferred means of diagnosis, especially in children.
There is a large percentage of children who receive the diagnosis of sensory integration dysfunction who might be better understood as having anxiety problems or even behavioral disorders. These problems can make a child look reactive, “touchie”, or unpredictable, and manifest in a manner similar to that characterized by occupational therapists as sensory integration dysfunction. And while this diagnosis is accepted widely among occupational therapists and also educators, these professionals have been criticized for overextending an already-poorly-supported model that attempts to explain emotional and behavioral problems that are better (and more simply) explained in other ways.
It should also be understood that there is general agreement that some children do have oversensitivity to many physical stimuli, the existence of this relatively small subset of children has lead to a general pattern of overdiagnosis in children who “look the same” but have other problems, and there are relatively few medical and psychological practitioners who agree that sensory integration dysfunction is the foundational problem in most children with this diagnosis.
While the physical methods employed by occupational therapists as treatment for SID are often palliative (they make the child feel better–much as a nice massage or physical contact would make anyone feel better), children misdiagnosed with sensory integration dysfunction will not receive appropriate psychological treatment (e.g., cognitive behavioral therapy) if they remain misdiagnosed.
The meaning of motor skills
Motor skills are actions that involve the movement of muscles in the body. They are divided into two groups: gross motor skills, which include the larger movements of arms, legs, feet, or the entire body (crawling, running, and jumping); and fine motor skills, which are smaller actions, such as grasping an object between the thumb and a finger or using the lips and tongue to taste objects. Both types of motor skills usually develop together, because many activities depend on the coordination of gross and fine motor skills.
The hands of newborn infants are closed most of the time and, like the rest of their bodies, they have little control over them. If their palms are touched, they will make a very tight fist, but this is an unconscious reflex action called the Darwinian reflex, and it disappears within two to three months. Similarly, infants will grasp at an object placed in their hands, but without any awareness that they are doing so. At some point their hand muscles relax, and they drop the object, equally unaware that they have let it fall. Babies may begin flailing at objects that interest them by two weeks of age but cannot grasp them. By eight weeks, they begin to discover and play with their hands, at first solely by touch, and then, at about three months, by sight as well. At this age, however, the deliberate grasp remains largely undeveloped.
Hand-eye coordination begins to develop between the ages of two and four months, inaugurating a period of trial-and-error practice at sighting objects and grabbing at them. At four or five months, most infants can grasp an object that is within reach, looking only at the object and not at their hands. Referred to as “top-level reaching,” this achievement is considered an important milestone in fine motor development. At the age of six months, infants can typically hold on to a small block briefly, and many have started banging objects. Although their grasp is still clumsy, they have acquired a fascination with grabbing small objects and trying to put them in their mouths. At first, babies will indiscriminately try to grasp things that cannot be grasped, such as pictures in a book, as well as those that can, such as a rattle or ball. During the latter half of the first year, they begin exploring and testing objects before grabbing, touching them with an entire hand and, eventually, poking them with an index finger.
One of the most significant fine motor accomplishments is the pincer grip, which typically appears at about 12 months. Initially, infants can only hold an object, such as a rattle, in their palm, wrapping their fingers (including the thumb) around it from one side. This awkward position is called the palmar grasp, which makes it difficult to hold on to and manipulate the object. By the age of eight to 10 months, a finger grasp begins, but objects can only be gripped with all four fingers pushing against the thumb, which still makes it awkward to grab small objects. The development of the pincer grip—the ability to hold objects between the thumb and index finger—gives the infant a more sophisticated ability to grasp and manipulate objects and also to deliberately drop them. By about the age of one, an infant can drop an object into a receptacle, compare objects held in both hands, stack objects, and nest them within each other.
Toddlers develop the ability to manipulate objects with increasing sophistication, including using their fingers to twist dials, pull strings, push levers, turn book pages, and use crayons to produce crude scribbles. Dominance of either the right or left hand usually emerges during this period as well. Toddlers also add a new dimension to touching and manipulating objects by simultaneously being able to name them. Instead of only random scribbles, theirdrawings include patterns, such as circles. Their play with blocks is more elaborate and purposeful than that of infants, and they can stack as many as six blocks. They are also able to fold a sheet of paper in half (with supervision), string large beads, manipulate snap toys, play with clay, unwrap small objects, and pound pegs.
The more delicate tasks facing preschool children, such as handling silverware or tying shoelaces, represent more challenge than most of the gross motor activities learned during this period of development. The central nervous system is still in the process of maturing sufficiently for complex messages from the brain to get to the child’s fingers. In addition, small muscles tire more easily than large ones, and the short, stubby fingers of preschoolers make delicate or complicated tasks more difficult. Finally, gross motor skills call for energy, which is boundless in preschoolers, while fine motor skills require patience, which is in shorter supply. Thus, there is considerable variation in fine motor development among this age group.
By the age of five, most children have clearly advanced beyond the fine motor skill development of the preschool age. They can draw recognizably human figures with facial features and legs connected to a distinct trunk. Besides drawing, five-year-olds can also cut, paste, and trace shapes. They can fasten visible buttons (as opposed to those at the back of clothing), and many can tie bows, including shoelace bows. Their right- or left-handedness is well established, and they use the preferred hand for writing and drawing.
School-age children six to 12 years old should have mastered hand and eye coordination. Early school age children should be able to use eating utensils and other tools, be able to help with household chores, such as sweeping, mopping, and dusting; care for pets; draw, paint, and engage in making crafts; and begin developing writing skills. Children will continue to fine-tune their fine motor skills through adolescence with such activities as sports, crafts, hobbies, learning musical instruments, computer use, and even video games.
Helping a child succeed in fine motor tasks requires planning, time, and a variety of play materials. Fine motor development can be encouraged by activities that youngsters enjoy, including crafts, puzzles, and playing with building blocks. Helping parents with everyday domestic activities, such as baking, can be fun for the child in addition to helping the child develop fine motor skills. For example, stirring batter provides a good workout for the hand and arm muscles, and cutting and spooning out cookie dough requires hand-eye coordination. Even a computer keyboard and mouse can provide practice in finger, hand, and hand-eye coordination. Because the development of fine motor skills plays a crucial role in school readiness and cognitive development, it is considered an important part of the preschool curriculum.
Beery-Buktenica Test—A test that identifies problems with visual perception, fine motor skills (especially hand control), and hand-eye coordination.
Darwinian reflex—An unconscious action in infants in which if a palm is touched, the infant makes a very tight fist. This instinct disappears within two to three months.
Developmental coordination disorder—A disorder of motor skills.
Gross motor skills—The abilities required to control the large muscles of the body for walking, running, sitting, crawling, and other activities. The muscles required to perform gross motor skills are generally found in the arms, legs, back, abdomen, and torso.
Hand-eye coordination—The ability to grasp or touch an object while looking at it.
Lincoln-Oseretsky Motor Development Scale—A test that assesses the development of motor skills.
Palmar grasp—A young infant’s primitive ability to hold an object in the palm by wrapping fingers and thumb around it from one side.
Pincer grip—The ability to hold objects between thumb and index finger, which typically develops in infants between 12 and 15 months of age.
Top-level reaching—The ability of an infant to grasp an object that is within reach, looking only at the object and not at the hands. Typically develops between four and five months of age.
Common motor skill problems
Fine motor skills can become impaired in a variety of ways, including injury, illness, stroke, and congenital deformities. An infant or child up to age five who is not developing new fine motor skills for that age may have a developmental disability. These problems can include major health conditions including cerebral palsy, mental retardation, blindness, deafness, and diabetes. Children with delays in fine motor skills development have difficulty controlling their coordinated body movements, especially with the face, hands, and fingers. Signs of fine motor skills delays include a failure to develop midline orientation by four months, reaching by five months, transferring objects from hand to hand by six months, a raking grasp by eight months, a mature pincer grip by one year, and index finger isolation by one year.
Developmental coordination disorder is a disorder of motor skills. A person with this disorder has a hard time with things like riding a bike, holding a pencil, and throwing a ball. People with this disorder are often called clumsy. Their movements are slow and awkward. People with developmental coordination disorder may also have a hard time completing tasks that involve movement of muscle groups in sequence. For example, such a person might be unable to do the following in order: open a closet door, get out a jacket, and put it on. It is thought that up to 6 percent of children may have developmental coordination disorder, according to the 2002 issue of the annual journal Clinical Reference Systems. The symptoms usually go unnoticed until the early years of elementary school. It is usually diagnosed in children who are between five and 11 years old.
Fine motor skills
|SOURCE: Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, 5th ed. and Child Development Institute, http://www.childdevelopmentinfo.com.|
|One to three months||Reflexively grasps finger or toy placed in hand.|
|Three months||Grasping reflex gone. Briefly holds small toy voluntarily when it is placed in the hand.|
|Four months||Holds and shakes rattle. Brings hands together to play with them. Reaches for objects but frequently misses them.|
|Five months||Grasps objects deliberately. Splashes water. Crumples paper.|
|Six months||Holds bottle. Grasps at own feet. May bring toes to mouth.|
|Seven months||Transfers toy from hand to hand. Bangs objects on table. Puts everything into the mouth. Loves playing with paper.|
|Nine months||Able to grasp small objects between thumb and forefinger.|
|Ten months||Points at objects with index finger. Lets go of objects deliberately.|
|Eleven months||Places object into another’s hand when requested, but does not release.|
|Twelve months||Places and releases object into another’s hand when requested. Rolls ball on floor. Starts to hold crayon and mark paper with it.|
|Fifteen months||Builds tower of two blocks. Repeatedly throws objects on floor. Starts to be able to take off clothing, starting with shoes.|
|Eighteen months||Builds tower of three blocks. Starts to feed self well with spoon. Turns book pages two or three at a time. Scribbles on paper.|
|Two years||Builds tower of six or seven blocks. Turns book pages one at a time. Turns door knobs and unscrews jar lids. Washes and dries hands. Uses spoon and fork well.|
|Two and a half years||Builds tower of eight blocks. Holds pencil between fingers instead of grasping with fist.|
|Three years||Builds tower of nine or ten blocks. Puts on shoes and socks. Can button and unbutton. Carries containers with little spilling or dropping.|
|Four years||Dresses self except for tying. Cuts with scissors, but not well. Washes and dries face.|
|Five years||Dresses without help. Ties shoes. Prints simple letters.|