Visual Processing and Autism: Bottom-Up Processing Explained

Understanding how students with autism process visual information can help teachers and pediatric therapists better support learning and participation. A recent research article published in the Journal of Autism and Developmental Disorders (Huang et al., 2025) explored how visual processing and autism are connected, specifically how autistic individuals handle local details versus the overall big picture. The findings highlight important differences in brain activity that can influence how students with autism see, interpret, and respond to their environment.

What the Researchers Studied

The study, Local and Global Visual Processing in Autism: A Systematic Review and Meta-Analysis of Neuroimaging Studies, analyzed brain imaging data from 15 studies involving over 500 participants.

Researchers compared how autistic and non-autistic individuals performed on visual tasks that measured two types of processing:

• Local processing: focusing on small details, such as finding a hidden shape within a complex picture.
• Global processing: integrating multiple details to recognize the big picture like seeing the full pattern or understanding how parts connect.

The goal was to see whether people with autism rely on different brain regions when completing these tasks and what this might reveal about how they process visual information.

Key Findings About Visual Processing and Autism

The study found consistent differences in brain activation patterns between autistic and non-autistic individuals:

1. Autistic participants showed greater activity in the visual cortex, especially in the right inferior occipital gyrus (Brodmann Area 19), which handles detailed visual input.
2. Non-autistic participants showed more activation in the parietal lobe, which integrates sensory information and helps form an overall picture.
3. Task performance was often similar between both groups meaning that while autistic individuals used different brain pathways, they completed visual tasks just as effectively.

This means that differences in visual processing and autism are not about ability but rather about approach. The autistic brain may rely more on sensory-driven pathways that focus on details, while non-autistic brains may rely more on top-down integration.

Understanding Bottom-Up Sensory Processing

The research team interpreted these results through the concept of bottom-up sensory processing.

• Bottom-up processing begins with raw sensory input, what we see, hear, or feel, and builds upward toward understanding.
• Top-down processing starts with context, experience, or prior knowledge using prediction and meaning to interpret sensory input.

For students with autism, the brain may rely more on bottom-up processing, meaning sensory details take priority before context or prediction. Each piece of visual information, color, brightness, or movement, is processed fully, which can make the world rich in detail but also overwhelming.

This aligns with predictive coding models in autism research, which suggest that autistic individuals use less “filtering” from past experiences and instead process each sensory moment as new.

Why This Matters for Educators and Therapists

Understanding how visual processing and autism interact helps professionals design more supportive environments for learning and participation.

What the Research Suggests

• Autistic individuals may excel at noticing patterns, visual details, and small differences.
• They might find it more difficult to see connections or understand how multiple steps or details fit together.
• Sensory input may be experienced more intensely, making busy visual environments harder to navigate.

By understanding these brain-based differences, educators and therapists can adjust their teaching and intervention strategies to reduce stress and build on strengths.