CVI: Response Interval

Learn about the impact of CVI on response time to visual stimuli, what this assessment area looks at, current research, and general ideas for accommodations.

Written by: Rachel Bennett

Access the video transcript.

At Perkins, we are a gathering place of ideas. The CVI visual behaviors synthesize current research and build on the work of leading theorists in the field. CVI is a lifelong disability and we want to ensure that all individuals with CVI are fully understood. The CVI visual behaviors are an ongoing need, they can change and they can improve for some, but the need never goes away. No one area is separated from the other—the CVI visual behaviors are highly connected and all can impact the individual with CVI at any time.

What is Response Interval?

This CVI behavior is directly impacted by all the other visual behaviors. Clutter, sensory integration, motion, light, color, and visual field abilities can all affect the response time to look at visual stimuli and recognize it. Also, a person with CVI cannot respond to visual stimuli if it can’t be seen or perceived. Response interval may be shorter for some with CVI when items are presented in their stronger visual fields, against a non-cluttered and high contrast background, and they are in a quiet, visually simple, distraction-free environment. 

Response interval is a key area that shows how people with CVI have to work much harder when attempting the same visual tasks as their sighted peers.

With an increased visual load, individuals with CVI have to grind it out, as opposed to having that instantaneous capture of information we see with a really efficient visual system.

Dr. Lotfi Merabet, The Science Behind CVI and Visual Fatigue

What are some compensatory strategies related to Response Interval

People with CVI have strategies and workarounds for so much in their daily lives. Compensatory skills help reduce visual search and fatigue and support access to learning. Often other sensory modalities can help be a bridge to perception and understanding, and help decrease the response interval for processing and recognition. 

 If my son is tired, it will take him more time to look at something and to find something in clutter. He also needs a lot of processing time when it comes to visual recognition. He instantly guesses because he feels like he doesn’t have enough time. But when he has access, which includes using his tactile and auditory skills, and is allowed the time to interpret what he’s looking at, he’ll be able to show you what he knows. He just needs to connect this hard visual task with his prior experiences.

CVI Parent

What are some look fors/questions when observing your child with CVI?

I had to reiterate to my child’s school team that she isn’t ‘misbehaving’ when she doesn’t look at the screen or the teacher, or gets up when she needs a break. She’s overwhelmed, she’s visually fatigued, and cannot respond to what’s in front of her.”

CVI Parent

What are some examples of adaptations and accommodations? 

All accommodations must be based on individual assessment. The following are meant to inspire and provide a general idea. Accommodations and instructional approaches must be student-specific. Access is individual. 

Adapting the environment and learning task is critical to support visual attention and recognition, which will help reduce the amount of effort it takes to use vision. When the environment, learning materials, and tasks are not accessible, then it will require a tremendous amount of energy for the person with CVI to use their vision (and they may not be able to or not want to use vision). Accessibility means that the person with CVI can go through their day and learn without draining all their energy to the point of exhaustion and pain. 

With the environmental and task accommodations in place:

Find more examples from a guide to common CVI IEP accommodations in the CVI Now IEP Guide. 

Following the science

Connecting current research of the brain, our visual system, and CVI to better understand the CVI visual behaviors.


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