Recent Issues. Chapter 12: The Behavior of Organisms at Fifty. Quote 15 Post author:B. F. Skinner Foundation Post published: April 19, 2019 Post category:Skinner's Quote of the Day “When a response was reinforced only in the presence of the light as an S Dee, the rat responded slowly in its absence (which, unfortunately, I called S Delta, hard to print) but responded immediately when the light came on.” (p. 127) You Might Also Like Cumulative Record. Chapter 14: Why We Need Teaching Machines. Quote 17 December 8, 2022 Cumulative Record. Chapter 11: Reinforcement Today. Quote 27 August 26, 2022 Cumulative Record. Chapter 17: Contingency Management in the Classroom. Quote 13 February 10, 2023