The Model Theory Research Collective is a group of scientists and researchers across the world who investigate how people think and reason.

“Deduction is that mode of reasoning which examines the state of things asserted in the premisses, forms a diagram of that state of things, perceives in the parts of the diagram relations not explicitly mentioned in the premisses, satisfies itself by mental experiments upon the diagram that these relations would always subsist, …and concludes their necessary, or probable, truth.” – Charles Sanders Peirce

The Model Theory Research Collective is a group of scientists, scholars, professors, and students who conduct and report studies on the strengths and failures of human reasoning. We focus on basic research and experimental data, as well as on developing computational models of higher-level cognitive processes. The webpage was set up, and continues to be maintained, by Sunny Khemlani (sunny.khemlani@nrl.navy.mil).

Experimental data in cognitive psychology suggest that humans reason and solve problems through the use of internal representations that can be mentally scrutinized and processed. The theory that posits the existence of such models and the mechanization thereof, known as mental model theory, was established by Philip Johnson-Laird (1983) and has proven extremely powerful in predicting and explaining higher-level cognition in humans.

This theory departs from the standard view, which assumes that there is a formal logical or probabilistic calculus in the mind. “Formal rules of inference play no part in inferences,” says Johnson-Laird, “though from Piaget onwards, psychologists have proposed theories based on them.”