Visual Perception : functioning, disorders and stimulation exercises

You are looking at this text right now. Your eyes receive the light signals, your brain interprets them as letters, words, phrases carrying meaning. This operation — which you perform without thinking — is the result of an extraordinarily complex neurological process. And this process, called visual perception, is much more than seeing: it is interpreting, organizing, giving meaning to what the eyes record.

The confusion between visual acuity (the sharpness of the image received by the eye) and visual perception (the way the brain processes and interprets this image) is one of the most common in supporting the visual difficulties of children. A child with perfectly corrected vision can still have significant visual perception difficulties — which impact their reading, writing, mathematical learning, and coordination. These difficulties often go unnoticed during a standard ophthalmological examination.

1. Visual acuity vs visual perception: two distinct things

Visual acuity refers to the eye's ability to form a sharp image — this is what the ophthalmologist measures with the Snellen chart or Landolt rings. It depends on the optical quality of the eye (cornea, lens, retina) and can be corrected with glasses or contact lenses.

Visual perception, on the other hand, is a brain skill — the brain's ability to process, organize, and interpret the information that the eyes transmit to it. It encompasses shape recognition, discrimination of similar details, spatial organization, understanding relationships between objects in space, visual memory, and figure-ground (distinguishing what is important from the background).

2. The visual pathway in the brain

From the retina to the primary visual cortex

The pathway of visual information begins at the retina, where photoreceptors (cones and rods) convert light into electrical signals. These signals travel via the optic nerves to the lateral geniculate body of the thalamus, and then to the primary visual cortex (V1) located in the occipital lobe. V1 processes the basic characteristics of the image — contour orientation, spatial frequencies, simple movements.

The two visual pathways: ventral and dorsal

From V1, visual information splits into two major parallel processing pathways. The ventral pathway (or "what" pathway) descends to the temporal lobes and specializes in identifying objects, faces, and written words — it answers the question "what is it?". The dorsal pathway (or "where/how" pathway) ascends to the parietal lobes and specializes in the spatial localization of objects and the guidance of visuomotor actions — it answers "where is it?" and "how do I get there?".

This dual architecture explains why brain lesions in different regions produce very different visual deficits: a temporal lesion may cause an inability to recognize familiar faces (prosopagnosia) while leaving intact the ability to locate and grasp objects; a parietal lesion may cause the opposite.

3. The 6 components of visual perception

4. Development of visual perception in children

Visual perception develops gradually from birth to adolescence. At birth, the newborn only perceives strong contrasts at a short distance (20-30 cm). The discrimination of simple shapes emerges in the first months. The recognition of faces develops very early — around 2-3 months, the infant prefers their mother's face to that of a stranger.

The perception of spatial relationships and the discrimination of complex shapes mainly develop between ages 3 and 7. It is during this window that activities such as drawing, puzzles, construction, and arts and crafts have the most impact on the development of visual perception. Visual memory and shape constancy refine until adolescence.

An important point: lateralization (the ability to clearly know if one is right-handed or left-handed) is closely linked to the development of spatial perception. An unestablished lateralization at ages 6-7 can generate left-right confusion that impacts reading (mirror letters) and writing.

5. Disorders of visual perception

Visual perception disorders in children often manifest at the onset of reading and writing, as these learnings intensively engage all components of visual perception — letter discrimination, visual memory of words, spatial organization of lines and the page.

6. Link with dyslexia and dyspraxia

Visual perception and dyslexia

Dyslexia is primarily a phonological disorder — a difficulty in processing the sounds of language and associating them with letters. However, difficulties in visual perception can coexist and exacerbate reading difficulties. The confusion of mirror letters (b/d, p/q) is often attributed to dyslexia when it may stem from a specific visual perception disorder or lateralization issue. An orthoptic and neuropsychological evaluation can distinguish between the two.

Visual perception and dyspraxia

Dyspraxia (Developmental Coordination Disorder, DCD) frequently involves difficulties in visuo-spatial perception — the dorsal pathway that guides motor actions in space. Dyspraxic children often struggle to copy geometric figures, organize their workspace, complete puzzles, or engage in sports that require quickly locating moving objects. Rehabilitation of visuo-spatial perception is an integral part of care in psychomotricity and occupational therapy.

7. Visual Perception and Aging

Aging affects visual perception in several ways. Contrast discrimination — the ability to distinguish close shades of gray — gradually decreases. The speed of visual processing slows down. Sensitivity to movement in the periphery of the visual field reduces, which has significant implications for driving. Figure-ground becomes less effective, which can contribute to difficulties in finding objects or reading on busy backgrounds.

These changes are normal up to a certain point. But a rapid or asymmetric degradation of visual perception may signal an eye pathology (AMD, glaucoma) or neurological condition (Alzheimer's disease, Stroke) that warrants medical consultation.

8. Neurological Aspects: Agnosia and Prosopagnosia

Cases of brain lesions affecting visual perception have provided neuroscience with some of its most spectacular discoveries about the functioning of the visual brain. Visual agnosia — the inability to visually recognize objects despite preserved visual acuity — can be extremely selective: some patients cannot recognize objects but perfectly recognize faces, while others do the opposite.

Prosopagnosia — the inability to recognize faces, even familiar ones — dramatically illustrates the specificity of visual perception circuits. Prosopagnosic patients recognize that they see a human face, but cannot identify whose it is — not even their own in a mirror. This dissociation between seeing and recognizing shows that face recognition is processed by a specialized circuit in the temporal fusiform gyrus, distinct from object recognition circuits.

9. Seven exercises to stimulate visual perception

• Games of 7 errors and images with differences: Intensively solicit visual discrimination and figure-ground. Progress from simple scenes to complex images. Comment on the differences found to anchor perceptual learning.
• Puzzles: The puzzle is the king exercise of visual perception — it simultaneously solicits shape discrimination, shape constancy, spatial perception, and figure-ground. Progress from 20-piece puzzles to complex compositions.
• Copies of geometric figures: Copying figures of increasing complexity (squares, diamonds, nested figures) trains spatial perception and visuomotor coordination. Rey's complex figure test is a standardized version of this exercise.
• Labyrinths and visual paths: Visually following a path (without touching the paper) trains visual tracking, figure-ground, and shape constancy. Progress from simple mazes to complex intertwined paths.
• Kim's games: Observe a series of objects, cover them, then identify those that have disappeared or changed places. Trains short-term visual memory and spatial discrimination.
• Spatial construction activities: Reproduce constructions with cubes or Lego according to a model — in 3D or from a 2D diagram. Intensively solicits spatial perception and mental rotation.
• Facial expression recognition: Training the recognition of micro-expressions and emotions on faces solicits the visual circuits specialized in facial recognition — a skill at the junction of visual perception and social cognition.

10. Monitoring and training tools

Training visual perception is more effective when it is regular, progressive, and documented. For professionals who support children or adults with visual perception difficulties — orthoptists, occupational therapists, psychomotor therapists, special education teachers — systematic tracking of progress is essential to adapt exercises and value acquisitions.