RESEARCH FOUNDATIONS

Visual processing differences (VPD) refer to difficulties in how the brain interprets, makes sense of, and uses visual information, even when eyesight (visual acuity) is normal. In other words, the eyes may see clearly, but the brain has trouble making sense of what is seen.  These differences sit at the intersection of vision, attention, cognition, and learning, and they are especially relevant in children’s development and education.

 Vision processing differences (VPD) are described using many overlapping terms because they span medicine, neuroscience, psychology, education, and allied health; each field has its own language for similar functional visual challenges. Terms such as visual processing disorder, cortical visual impairment, non-verbal learning difficulties, and visual–spatial or visual–cognitive challenges often reflect perspective rather than distinct conditions. 

Traditionally, vision has been framed narrowly around eye health and clarity of eyesight, while learning and cognition have been addressed separately. As a result, difficulties in interpreting, integrating, and using visual information for learning have been inconsistently labelled. Increasingly, these challenges are recognised as differences in functional visual access rather than a single diagnosis. Vis-CAT® aligns with this view by focusing on how children use their vision to interpret visual information and support attention, learning, and participation, thereby cutting across these overlapping terms, enabling early identification and intervention of challenges. 

Recent research shows that visual processing differences are real, brain-based differences in how visual information is interpreted, not problems with eyesight or effort. Studies using brain imaging and behavioural testing show that some children have difficulty with the brain systems that support visual–spatial understanding, attention, and visual memory, which can affect learning in areas like reading, maths, handwriting, and organisation. 

Importantly, these differences can exist even when eyesight tests are normal and intelligence is typical or high. Researchers are also refining how these difficulties are defined such as reframing Nonverbal Learning Disability as Developmental Visual Spatial Disorder (DVSD) and developing better tools to identify children earlier, when targeted support can have the greatest impact.

DVSD is different from both eye and attention problems. Children with DVSD usually have normal eyesight and pass standard eye tests—the difficulty lies in how the brain processes and makes sense of visual–spatial information, such as understanding layouts, relationships, and visual organisation. It is also not primarily an attention disorder: children may seem inattentive or overwhelmed, but this is often because visually complex tasks require much more effort, not because they can’t focus in general. In short, eyesight problems affect how clearly the eyes see, attention problems affect the ability to focus, and DVSD affects how the brain interprets visual–spatial information.

Vis-CAT fits in as an early identification and screening tool for visual–spatial processing differences. While standard eye tests assess how clearly a child sees, and behavioural checklists focus on attention or learning, Vis-CAT is designed to tap directly into visual–spatial attention and processing skills that are often missed in routine assessments. By providing a simple, child-friendly way to detect early markers of visual–spatial difficulty, Vis-CAT helps identify children who may be at risk for challenges such as DVSD, allowing support to be put in place earlier—before learning difficulties become entrenched.

Vis-CAT is grounded in vision science and clinical research, building on the Novel Dot Pattern Assessment (NDPA) developed by Dr. Christine Nearchou and her team, which has been trialled in school settings and clinics to identify early visual–spatial processing differences in children. The NDPA research demonstrated that this task reliably highlights challenges in visual–spatial attention that standard eye tests often miss. Drawing on these validated methods, Vis-CAT has been piloted in real-world educational and clinical settings to ensure it is child-friendly, engaging, and practical, with data collected and analysed to refine scoring and interpretation. Designed as an evidence-informed early screening tool rather than a diagnostic test, Vis-CAT helps detect potential visual–spatial difficulties and enables timely referrals and support programs.

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