Size in context: the Ebbinghaus illusion

Center radius (px):

Surround count:

Small surround radius (px):

Large surround radius (px):

Small spacing (px):

Large spacing (px):

Animate surround (dynamic variant)

Show guides

Tip: Both center disks are physically identical; surrounding context changes perceived size.
Reference: Roberts, B., Harris, M. G., & Yates, T. A. (2005). The roles of inducer size and distance in the Ebbinghaus illusion (Titchener circles). Perception, 34(7), 847–856. doi:10.1068/p5273

Demo for Lecture: Basic Neuro-cognitive Psychology.
Created by Z. Shi, msense Lab.