By: Daniella Rutner, OD
Visual perceptual skills refer to the ability to identify tangible features of spatially abstract patterns and organized them in such a way that they provide for the basis for classifying information in a meaningful way. 80% of learning is achieved through vision. Vision disorders can cause or contribute to academic difficulties. Effective learning requires two components, visual efficiency and visual information processing. Such that, learning related vision problem represents difficulty in one or both these components that can limit a one’s ability to perform to one’s full learning potential. However, there is no unitary visual deficit that accounts for all expressions of academic difficulty and not all learning problems are visually based.
It has been noted that people with reading difficulties often have higher incidence of poor ocular alignment at near such as convergence insufficiency, poor oculomotor function and overall visual inefficiency. These conditions and inefficiencies lead to eye discomfort, which makes it increasingly more difficult to complete near vision tasks in an accurate and timely manner. These symptoms may lead to distraction, inattention, and task avoidance, which often compound the problem.
Learning makes an immeasurable shift at around the end of third to fourth grade where learning to read is replaced with reading to learn. It is at that stage where visual efficiency plays a key role as the demands for speed and comprehension becomes greater and simultaneously print size is smaller while spacing decreases between letters, words and lines. In addition, as grade levels advanced there is a substantial increase in the time as the amount of near work increases (e.g. homework averages about 10 to 15 minutes per grade).
The attentional capacity of an individual is finite. As such, when attentional capacity is diverted to manage the visual efficiency problem it is at the expense of the information processing required for comprehensive of the material.
Visual information processing provides the capability to organize, structure, interpret visual stimuli in a meaningful way. The necessary processing skills are visual spatial orientation (i.e. bilateral integration and laterality) and visual analysis skills (i.e. visual discrimination, visual memory and visualization, auditory visual integration, visual motor integration).
Learning to read requires both phonetic and eidetic processing. Visual perceptual deficits that interfere with consistent recognition may impede these processes necessary for learning to read.
There are several key elements in visual perception as they relate to learning. Spatial orientation refers to the ability to orient oneself in space. Visual spatial ability requires the recall of the spatial location of previously seen stimulus. Difficulties in visual spatial ability typically presents as excessive reversal and/or transpositions of letter or syllables and often with poor eye movements. Frequently, these patients are categorized as dyslexic. However, learning difficulties are not limited to reading. Difficulties in visual spatial orientation cross over to mathematical difficulties. This is often due to inaccuracy in copying, spacing of numbers and alignment of columns. It impedes higher mental mathematical abilities that require visualization such as geometry and conceptual relationships.
Another aspect of spatial orientation is laterality or directionality. Laterality is an internal awareness that distinguishes one side of the body from the other. Directionality is the ability to project laterality into the physical world.
Students with poor visual discrimination, tend to confuse letter, shapes, orientation and size. These students face challenges in perceiving the whole word and building sight recognition vocabulary. Symptoms often present as miscalling of similarly spelled words or miscalling simple words. These simple words are often connecters such as and, the, and a, effects in the reading comprehension. Typically, these students read phonetically and therefore read more slowly resulting in increasing the time for the completion of reading tasks. Visual form perception is the ability to discriminate or assemble a visual form or letters that are incomplete (visual closure), hidden (figure-ground), disorganized (visual organization), broken apart (form board).
Visual memory is the ability to retain visual stimuli presented for a brief period of time. There are two distinct types of visual memory; visual sequential memory and visual spatial memory. Visual sequential memory is the ability to perceive and remember a sequence of objects, letters, words, forms or other symbols in the same order as originally seen. Visual spatial memory is the ability to remember the spatial location of the stimulus. Visual memory and visualization are essential elements in spelling and writing. Unfortunately, the English language is filled with rules and exceptions to the rule. Visual imagery and visualization permits proper spelling despite the many phonetic irregularities that exist. Deficit in this area of visual perceptual is more applicable in younger grade where children are tested in spelling and expected to turn in hand written assignment. This becomes less of an obstacle as children use word processing programs that feature spell and grammar check.
In individuals with perceptual disabilities there is often an inability to integrate information arriving as input, with other stimuli, from the same or different sensory modality. There are several sensory modalities that are integrated auditory-visual, visual-motor and tactile visual motor.
Auditory –visual processing skills refer to the ability to recognize the concrete features of acoustical patterns and apply them to visual stimuli. It is essential for establishing the connection between sound and a visual symbol. This serves as the basis for which learning letter sound and phonemic analysis necessary for early reading.
Visual Motor integration is the ability to merge visual information processing with fine motor movements and to translate abstract visual information into a fine motor activity typically copying and writing. These students tend to have poor handwriting ability.
A test that requires the patient to integrate visual motor and tactile requires considerable manipulative dexterity. It provides an excellent opportunity for observation of the process involved.
Perceptual speed is one of the major cognitive processing dimensions. Poor processing speed is a characteristic of many learning-disabled patients. Many individuals with visual, learning and perceptual disabilities can successfully complete visual processing tasks if they do not have time limits. Automaticity is an important skill as it reduces the exertion of the visual system during reading.
Student with visual perceptual deficits tend to perform poorly in school. It is important to note that not all individual with a learning disability have concurrent vision related problems. But for those individual who do, treatment is to enable the individual to take full advantage of the opportunities of learning. This can have the most profound effect on a child image of self worth and ultimately success in the future.
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