Definition
Change Blindness is the inability to detect a change in a visual stimulus when that change occurs during a brief disruption, such as an eye blink, a screen flicker, or an object passing between the observer and the scene.
Why It Matters
It exposes the limits of human attention and perception, warning that we are often unaware of significant changes in our environment if our focus is elsewhere.
Core Concepts
- Visual Disruption Requirement: Changes that happen in plain view are usually noticed; change blindness occurs when the “motion signal” of the change is masked.
- Identity Swapping: Iconic experiments (e.g., Levin & Simons) show that about half of people don’t notice when the person they are talking to is swapped for someone else behind a passing door.
- Categorical Processing: We tend to perceive the world in broad categories (e.g., “clerk,” “old man”) rather than specific details. If the replacement fits the same category, the change is often missed.
- Social Group Bias: We are more likely to notice changes in people who belong to our own social, racial, or age groups.